refactor resizing to address race condition on Windows

ios/src/PolyvoxFilamentFFIApi.cpp

@@ -2,475 +2,446 @@
 #include "PolyvoxFilamentFFIApi.h"
 
 #include "FilamentViewer.hpp"
-#include "filament/LightManager.h"
 #include "Log.hpp"
 #include "ThreadPool.hpp"
+#include "filament/LightManager.h"
 
-#include <thread>
 #include <functional>
+#include <mutex>
+#include <thread>
 
 using namespace polyvox;
 
-class RenderLoop
+class RenderLoop {
-{
 public:
-    explicit RenderLoop()
+  explicit RenderLoop() {
-    {
+    _t = new std::thread([this]() {
-        _t = new std::thread([this]()
+      while (!_stop) {
-                             {
+        {
-			while(!_stop) {
+          if (_rendering) {
-                if(_rendering) {
+            doRender();
-                    doRender();
+          }
-                }
+        }
-				std::function<void()> task;
+        std::function<void()> task;
-				{
+        {
-					std::unique_lock<std::mutex> lock(_access);
+          std::unique_lock<std::mutex> lock(_access);
-					if(_tasks.empty()) {
+          if (_tasks.empty()) {
-						_cond.wait_for(lock, std::chrono::duration<float, std::milli>(_frameIntervalInMilliseconds));
+            _cond.wait_for(lock, std::chrono::duration<float, std::milli>(
-						continue;
+                                     _frameIntervalInMilliseconds));
-					}
+            continue;
-					task = std::move(_tasks.front());
+          }
-					_tasks.pop_front();    
+          task = std::move(_tasks.front());
-                }
+          _tasks.pop_front();
-				task();
+        }
-			} });
+        task();
-    }
+      }
-    ~RenderLoop()
+    });
-    {
+  }
-        _stop = true;
+  ~RenderLoop() {
-        _t->join();
+    _stop = true;
-    }
+    _t->join();
+  }
 
-    void* const createViewer(
+  void *const createViewer(void *const context, void *const platform,
-        void* const context, 
+                           const char *uberArchivePath,
-        void* const platform,
+                           const ResourceLoaderWrapper *const loader,
-        const char* uberArchivePath,
+                           void (*renderCallback)(void *), void *const owner) {
-        const ResourceLoaderWrapper* const loader, 
+    _renderCallback = renderCallback;
-        void (*renderCallback)(void*), void* const owner
+    _renderCallbackOwner = owner;
-    ) {
+    std::packaged_task<FilamentViewer *()> lambda([&]() mutable {
-        _renderCallback = renderCallback;
+      std::thread::id this_id = std::this_thread::get_id();
-        _renderCallbackOwner = owner;
+      return new FilamentViewer(context, loader, platform, uberArchivePath);
-        std::packaged_task<FilamentViewer*()> lambda([&]() mutable
+    });
-                                                           { 
+    auto fut = add_task(lambda);
-                                                            return new FilamentViewer(context, loader, platform, uberArchivePath); 
+    fut.wait();
-                                                            });
+    _viewer = fut.get();
-        auto fut = add_task(lambda);
+    return (void *const)_viewer;
-        fut.wait();
+  }
-        _viewer = fut.get();
-        return (void* const)_viewer;
-    }
 
-    void destroyViewer() { 
+  void destroyViewer() {
-        std::packaged_task<void()> lambda([&]() mutable {
+    std::packaged_task<void()> lambda([&]() mutable {
-            _rendering = false;
+      _rendering = false;
-            destroy_filament_viewer(_viewer);
+      destroy_filament_viewer(_viewer);
-            _viewer = nullptr;       
+      _viewer = nullptr;
-        });
+    });
-        auto fut = add_task(lambda);
+    auto fut = add_task(lambda);
-        fut.wait();
+    fut.wait();
-    }
+  }
 
-    void setRendering(bool rendering)
+  void setRendering(bool rendering) {
-    {
+    std::packaged_task<void()> lambda(
-        std::packaged_task<void()> lambda([&]() mutable
+        [&]() mutable { this->_rendering = rendering; });
-                                                           { 
+    auto fut = add_task(lambda);
-                                                            this->_rendering = rendering;
+    fut.wait();
-                                                            });
+  }
-        auto fut = add_task(lambda);
-        fut.wait();
-    }
 
-    void doRender()
+  void doRender() {
-    {
+    render(_viewer, 0, nullptr, nullptr, nullptr);
-        render(_viewer, 0, nullptr, nullptr, nullptr);
+    _renderCallback(_renderCallbackOwner);
-        _renderCallback(_renderCallbackOwner);
+  }
-    }
 
-    void setFrameIntervalInMilliseconds(float frameIntervalInMilliseconds) {
+  void setFrameIntervalInMilliseconds(float frameIntervalInMilliseconds) {
-        _frameIntervalInMilliseconds = frameIntervalInMilliseconds;
+    _frameIntervalInMilliseconds = frameIntervalInMilliseconds;
-    }
+  }
 
-    template <class Rt>
+  template <class Rt>
-    auto add_task(std::packaged_task<Rt()> &pt) -> std::future<Rt>
+  auto add_task(std::packaged_task<Rt()> &pt) -> std::future<Rt> {
-    {
+    std::unique_lock<std::mutex> lock(_access);
-        std::unique_lock<std::mutex> lock(_access);
+    auto ret = pt.get_future();
-        auto ret = pt.get_future();
+    _tasks.push_back([pt = std::make_shared<std::packaged_task<Rt()>>(
-        _tasks.push_back([pt = std::make_shared<std::packaged_task<Rt()>>(std::move(pt))]
+                          std::move(pt))] { (*pt)(); });
-                         { (*pt)(); });
+    _cond.notify_one();
-        _cond.notify_one();
+    return ret;
-        return ret;
+  }
-    }
 
 private:
-    bool _stop = false;
+  bool _stop = false;
-    bool _rendering = false;
+  bool _rendering = false;
-    float _frameIntervalInMilliseconds = 1000.0 / 60.0;
+  float _frameIntervalInMilliseconds = 1000.0 / 60.0;
-    std::mutex _access;
+  std::mutex _access;
-    FilamentViewer *_viewer = nullptr;
+  FilamentViewer *_viewer = nullptr;
-    void (*_renderCallback)(void* const) = nullptr;
+  void (*_renderCallback)(void *const) = nullptr;
-    void *_renderCallbackOwner = nullptr;
+  void *_renderCallbackOwner = nullptr;
-    std::thread *_t = nullptr;
+  std::thread *_t = nullptr;
-    std::condition_variable _cond;
+  std::condition_variable _cond;
-    std::deque<std::function<void()>> _tasks;
+  std::deque<std::function<void()>> _tasks;
 };
 
-extern "C"
+extern "C" {
-{
 
-    static RenderLoop *_rl;
+static RenderLoop *_rl;
 
-    FLUTTER_PLUGIN_EXPORT void* const create_filament_viewer_ffi(
+FLUTTER_PLUGIN_EXPORT void *const create_filament_viewer_ffi(
-        void* const context,
+    void *const context, void *const platform, const char *uberArchivePath,
-        void* const platform,
+    const ResourceLoaderWrapper *const loader,
-        const char* uberArchivePath,
+    void (*renderCallback)(void *const renderCallbackOwner),
-        const ResourceLoaderWrapper* const loader, 
+    void *const renderCallbackOwner) {
-        void (*renderCallback)(void* const renderCallbackOwner), 
+  if (!_rl) {
-        void* const renderCallbackOwner) {
+    _rl = new RenderLoop();
-        if (!_rl)
+  }
-        {
+  return _rl->createViewer(context, platform, uberArchivePath, loader,
-            _rl = new RenderLoop();
+                           renderCallback, renderCallbackOwner);
-        }
+}
-        return _rl->createViewer(context, platform,uberArchivePath, loader, renderCallback, renderCallbackOwner);
+
-    }
+FLUTTER_PLUGIN_EXPORT void destroy_filament_viewer_ffi(void *const viewer) {
-
+  _rl->destroyViewer();
-    FLUTTER_PLUGIN_EXPORT void destroy_filament_viewer_ffi(void* const viewer) {
+}
-        _rl->destroyViewer();
+
-    }
+FLUTTER_PLUGIN_EXPORT void create_swap_chain_ffi(void *const viewer,
-
+                                                 void *const surface,
-    FLUTTER_PLUGIN_EXPORT void create_swap_chain_ffi(void* const viewer, void* const surface, uint32_t width, uint32_t height)
+                                                 uint32_t width,
-    {
+                                                 uint32_t height) {
-        Log("Creating swapchain %dx%d", width, height);
+  Log("Creating swapchain %dx%d", width, height);
-        std::packaged_task<void()> lambda([&]() mutable
+  std::packaged_task<void()> lambda(
-                                          { 
+      [&]() mutable { create_swap_chain(viewer, surface, width, height); });
-                                            create_swap_chain(viewer, surface, width, height); 
+  auto fut = _rl->add_task(lambda);
-                                            });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+
-    }
+FLUTTER_PLUGIN_EXPORT void destroy_swap_chain_ffi(void *const viewer) {
-
+  Log("Destroying swapchain");
-    FLUTTER_PLUGIN_EXPORT void destroy_swap_chain_ffi(void* const viewer)
+  std::packaged_task<void()> lambda(
-    {
+      [&]() mutable { 
-        Log("Destroying swapchain");
+        destroy_swap_chain(viewer); 
-        std::packaged_task<void()> lambda([&]() mutable
+    });
-                                          { 
+  auto fut = _rl->add_task(lambda);
-                                            destroy_swap_chain(viewer);
+  fut.wait();
-                                            });
+}
-        auto fut = _rl->add_task(lambda);
+
-        fut.wait();
+FLUTTER_PLUGIN_EXPORT void create_render_target_ffi(void *const viewer,
-    }
+                                                    intptr_t nativeTextureId,
-
+                                                    uint32_t width,
-    FLUTTER_PLUGIN_EXPORT void create_render_target_ffi(void* const viewer, intptr_t nativeTextureId, uint32_t width, uint32_t height)
+                                                    uint32_t height) {
-    {
+  std::packaged_task<void()> lambda([&]() mutable {
-        std::packaged_task<void()> lambda([&]() mutable
+    create_render_target(viewer, nativeTextureId, width, height);
-                                          { create_render_target(viewer, nativeTextureId, width, height); });
+  });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-    }
+}
-
+
-    FLUTTER_PLUGIN_EXPORT void update_viewport_and_camera_projection_ffi(void* const viewer, const uint32_t width, const uint32_t height, const float scaleFactor)
+FLUTTER_PLUGIN_EXPORT void update_viewport_and_camera_projection_ffi(
-    {
+    void *const viewer, const uint32_t width, const uint32_t height,
-        Log("Update viewport  %dx%d", width, height);
+    const float scaleFactor) {
-        std::packaged_task<void()> lambda([&]() mutable
+  Log("Update viewport  %dx%d", width, height);
-                                          { 
+  std::packaged_task<void()> lambda([&]() mutable {
-                                            update_viewport_and_camera_projection(viewer, width, height, scaleFactor); 
+    update_viewport_and_camera_projection(viewer, width, height, scaleFactor);
-                                            });
+  });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-    }
+}
-
+
-    FLUTTER_PLUGIN_EXPORT void set_rendering_ffi(void* const viewer, bool rendering)
+FLUTTER_PLUGIN_EXPORT void set_rendering_ffi(void *const viewer,
-    {
+                                             bool rendering) {
-        if (!_rl)
+  if (!_rl) {
-        {
+    Log("No render loop!"); // PANIC?
-            Log("No render loop!"); // PANIC?
+  } else {
-        }
+    if (rendering) {
-        else
+      Log("Set rendering to true");
-        {
+    } else {
-            if (rendering)
+      Log("Set rendering to false");
-            {
+    }
-                Log("Set rendering to true");
+    _rl->setRendering(rendering);
-            }
+  }
-            else
+}
-            {
+
-                Log("Set rendering to false");
+FLUTTER_PLUGIN_EXPORT void
-            }
+set_frame_interval_ffi(float frameIntervalInMilliseconds) {
-            _rl->setRendering(rendering);
+  _rl->setFrameIntervalInMilliseconds(frameIntervalInMilliseconds);
-        }
+}
-    }
+
-
+FLUTTER_PLUGIN_EXPORT void render_ffi(void *const viewer) {
-    FLUTTER_PLUGIN_EXPORT void set_frame_interval_ffi(float frameIntervalInMilliseconds) {
+  std::packaged_task<void()> lambda([&]() mutable { _rl->doRender(); });
-        _rl->setFrameIntervalInMilliseconds(frameIntervalInMilliseconds);
+  auto fut = _rl->add_task(lambda);
-    }
+  fut.wait();
-
+}
-    FLUTTER_PLUGIN_EXPORT void render_ffi(void* const viewer)
+
-    {
+FLUTTER_PLUGIN_EXPORT void
-        std::packaged_task<void()> lambda([&]() mutable
+set_background_color_ffi(void *const viewer, const float r, const float g,
-                                          { 
+                         const float b, const float a) {
-                                            _rl->doRender(); 
+  std::packaged_task<void()> lambda(
-                                            });
+      [&]() mutable { set_background_color(viewer, r, g, b, a); });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-    }
+}
-
+
-    FLUTTER_PLUGIN_EXPORT void set_background_color_ffi(void* const viewer, const float r, const float g, const float b, const float a)
+FLUTTER_PLUGIN_EXPORT EntityId load_gltf_ffi(void *const assetManager,
-    {
+                                             const char *path,
-        std::packaged_task<void()> lambda([&]() mutable
+                                             const char *relativeResourcePath) {
-                                          { set_background_color(viewer, r, g, b, a); });
+  std::packaged_task<EntityId()> lambda([&]() mutable {
-        auto fut = _rl->add_task(lambda);
+    return load_gltf(assetManager, path, relativeResourcePath);
-        fut.wait();
+  });
-    }
+  auto fut = _rl->add_task(lambda);
-
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT EntityId load_gltf_ffi(void* const assetManager, const char *path, const char *relativeResourcePath)
+  return fut.get();
-    {
+}
-        std::packaged_task<EntityId()> lambda([&]() mutable
+
-                                              { return load_gltf(assetManager, path, relativeResourcePath); });
+FLUTTER_PLUGIN_EXPORT EntityId load_glb_ffi(void *const assetManager,
-        auto fut = _rl->add_task(lambda);
+                                            const char *path, bool unlit) {
-        fut.wait();
+  std::packaged_task<EntityId()> lambda(
-        return fut.get();
+      [&]() mutable { return load_glb(assetManager, path, unlit); });
-    }
+  auto fut = _rl->add_task(lambda);
-
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT EntityId load_glb_ffi(void* const assetManager, const char *path, bool unlit)
+  return fut.get();
-    {
+}
-        std::packaged_task<EntityId()> lambda([&]() mutable
+
-                                              { return load_glb(assetManager, path, unlit); });
+FLUTTER_PLUGIN_EXPORT void clear_background_image_ffi(void *const viewer) {
-        auto fut = _rl->add_task(lambda);
+  std::packaged_task<void()> lambda([&] { clear_background_image(viewer); });
-        fut.wait();
+  auto fut = _rl->add_task(lambda);
-        return fut.get();
+  fut.wait();
-    }
+}
-
+
-    FLUTTER_PLUGIN_EXPORT void clear_background_image_ffi(void* const viewer)
+FLUTTER_PLUGIN_EXPORT void set_background_image_ffi(void *const viewer,
-    {
+                                                    const char *path,
-        std::packaged_task<void()> lambda([&]
+                                                    bool fillHeight) {
-                                          { 
+  std::packaged_task<void()> lambda(
-                                            clear_background_image(viewer); 
+      [&] { set_background_image(viewer, path, fillHeight); });
-                                            });
+  auto fut = _rl->add_task(lambda);
-        auto fut = _rl->add_task(lambda);
+  fut.wait();
-        fut.wait();
+}
-    }
+FLUTTER_PLUGIN_EXPORT void set_background_image_position_ffi(void *const viewer,
-
+                                                             float x, float y,
-    FLUTTER_PLUGIN_EXPORT void set_background_image_ffi(void* const viewer, const char *path, bool fillHeight)
+                                                             bool clamp) {
-    {
+  std::packaged_task<void()> lambda(
-        std::packaged_task<void()> lambda([&]
+      [&] { set_background_image_position(viewer, x, y, clamp); });
-                                          { 
+  auto fut = _rl->add_task(lambda);
-                                            set_background_image(viewer, path, fillHeight); 
+  fut.wait();
-                                            });
+}
-        auto fut = _rl->add_task(lambda);
+FLUTTER_PLUGIN_EXPORT void set_tone_mapping_ffi(void *const viewer,
-        fut.wait();
+                                                int toneMapping) {
-    }
+  std::packaged_task<void()> lambda(
-    FLUTTER_PLUGIN_EXPORT void set_background_image_position_ffi(void* const viewer, float x, float y, bool clamp)
+      [&] { set_tone_mapping(viewer, toneMapping); });
-    {
+  auto fut = _rl->add_task(lambda);
-        std::packaged_task<void()> lambda([&]
+  fut.wait();
-                                          { set_background_image_position(viewer, x, y, clamp); });
+}
-        auto fut = _rl->add_task(lambda);
+FLUTTER_PLUGIN_EXPORT void set_bloom_ffi(void *const viewer, float strength) {
-        fut.wait();
+  std::packaged_task<void()> lambda([&] { set_bloom(viewer, strength); });
-    }
+  auto fut = _rl->add_task(lambda);
-    FLUTTER_PLUGIN_EXPORT void set_tone_mapping_ffi(void* const viewer, int toneMapping)
+  fut.wait();
-    {
+}
-        std::packaged_task<void()> lambda([&]
+FLUTTER_PLUGIN_EXPORT void load_skybox_ffi(void *const viewer,
-                                          { set_tone_mapping(viewer, toneMapping); });
+                                           const char *skyboxPath) {
-        auto fut = _rl->add_task(lambda);
+  std::packaged_task<void()> lambda([&] { load_skybox(viewer, skyboxPath); });
-        fut.wait();
+  auto fut = _rl->add_task(lambda);
-    }
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT void set_bloom_ffi(void* const viewer, float strength)
+}
-    {
+FLUTTER_PLUGIN_EXPORT void load_ibl_ffi(void *const viewer, const char *iblPath,
-        std::packaged_task<void()> lambda([&]
+                                        float intensity) {
-                                          { set_bloom(viewer, strength); });
+  std::packaged_task<void()> lambda(
-        auto fut = _rl->add_task(lambda);
+      [&] { load_ibl(viewer, iblPath, intensity); });
-        fut.wait();
+  auto fut = _rl->add_task(lambda);
-    }
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT void load_skybox_ffi(void* const viewer, const char *skyboxPath)
+}
-    {
+FLUTTER_PLUGIN_EXPORT void remove_skybox_ffi(void *const viewer) {
-        std::packaged_task<void()> lambda([&]
+  std::packaged_task<void()> lambda([&] { remove_skybox(viewer); });
-                                          { load_skybox(viewer, skyboxPath); });
+  auto fut = _rl->add_task(lambda);
-        auto fut = _rl->add_task(lambda);
+  fut.wait();
-        fut.wait();
+}
-    }
+
-    FLUTTER_PLUGIN_EXPORT void load_ibl_ffi(void* const viewer, const char *iblPath, float intensity)
+FLUTTER_PLUGIN_EXPORT void remove_ibl_ffi(void *const viewer) {
-    {
+  std::packaged_task<void()> lambda([&] { remove_ibl(viewer); });
-        std::packaged_task<void()> lambda([&]
+  auto fut = _rl->add_task(lambda);
-                                          { load_ibl(viewer, iblPath, intensity); });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+
-    }
+EntityId add_light_ffi(void *const viewer, uint8_t type, float colour,
-    FLUTTER_PLUGIN_EXPORT void remove_skybox_ffi(void* const viewer)
+                       float intensity, float posX, float posY, float posZ,
-    {
+                       float dirX, float dirY, float dirZ, bool shadows) {
-        std::packaged_task<void()> lambda([&]
+  std::packaged_task<EntityId()> lambda([&] {
-                                          { remove_skybox(viewer); });
+    return add_light(viewer, type, colour, intensity, posX, posY, posZ, dirX,
-        auto fut = _rl->add_task(lambda);
+                     dirY, dirZ, shadows);
-        fut.wait();
+  });
-    }
+  auto fut = _rl->add_task(lambda);
-    
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT void remove_ibl_ffi(void* const viewer)
+  return fut.get();
-    {
+}
-        std::packaged_task<void()> lambda([&]
+
-                                          { remove_ibl(viewer); });
+FLUTTER_PLUGIN_EXPORT void remove_light_ffi(void *const viewer,
-        auto fut = _rl->add_task(lambda);
+                                            EntityId entityId) {
-        fut.wait();
+  std::packaged_task<void()> lambda([&] { remove_light(viewer, entityId); });
-    }
+  auto fut = _rl->add_task(lambda);
-
+  fut.wait();
-    EntityId add_light_ffi(void* const viewer, uint8_t type, float colour, float intensity, float posX, float posY, float posZ, float dirX, float dirY, float dirZ, bool shadows)
+}
-    {
+
-        std::packaged_task<EntityId()> lambda([&]
+FLUTTER_PLUGIN_EXPORT void clear_lights_ffi(void *const viewer) {
-                                              { return add_light(viewer, type, colour, intensity, posX, posY, posZ, dirX, dirY, dirZ, shadows); });
+  std::packaged_task<void()> lambda([&] { clear_lights(viewer); });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-        return fut.get();
+}
-    }
+
-
+FLUTTER_PLUGIN_EXPORT void remove_asset_ffi(void *const viewer,
-    FLUTTER_PLUGIN_EXPORT void remove_light_ffi(void* const viewer, EntityId entityId)
+                                            EntityId asset) {
-    {
+  std::packaged_task<void()> lambda([&] { remove_asset(viewer, asset); });
-        std::packaged_task<void()> lambda([&]
+  auto fut = _rl->add_task(lambda);
-                                          { remove_light(viewer, entityId); });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+FLUTTER_PLUGIN_EXPORT void clear_assets_ffi(void *const viewer) {
-    }
+  std::packaged_task<void()> lambda([&] { clear_assets(viewer); });
-
+  auto fut = _rl->add_task(lambda);
-    FLUTTER_PLUGIN_EXPORT void clear_lights_ffi(void* const viewer)
+  fut.wait();
-    {
+}
-        std::packaged_task<void()> lambda([&]
+
-                                          { clear_lights(viewer); });
+FLUTTER_PLUGIN_EXPORT bool set_camera_ffi(void *const viewer, EntityId asset,
-        auto fut = _rl->add_task(lambda);
+                                          const char *nodeName) {
-        fut.wait();
+  std::packaged_task<bool()> lambda(
-    }
+      [&] { return set_camera(viewer, asset, nodeName); });
-
+  auto fut = _rl->add_task(lambda);
-    FLUTTER_PLUGIN_EXPORT void remove_asset_ffi(void* const viewer, EntityId asset)
+  fut.wait();
-    {
+  return fut.get();
-        std::packaged_task<void()> lambda([&]
+}
-                                          { remove_asset(viewer, asset); });
+
-        auto fut = _rl->add_task(lambda);
+FLUTTER_PLUGIN_EXPORT void set_bone_animation_ffi(
-        fut.wait();
+    void *assetManager, EntityId asset, const float *const frameData,
-    }
+    int numFrames, int numBones, const char **const boneNames,
-    FLUTTER_PLUGIN_EXPORT void clear_assets_ffi(void* const viewer)
+    const char **const meshName, int numMeshTargets, float frameLengthInMs) {
-    {
+  std::packaged_task<void()> lambda([&] {
-        std::packaged_task<void()> lambda([&]
+    set_bone_animation(assetManager, asset, frameData, numFrames, numBones,
-                                          { clear_assets(viewer); });
+                       boneNames, meshName, numMeshTargets, frameLengthInMs);
-        auto fut = _rl->add_task(lambda);
+  });
-        fut.wait();
+  auto fut = _rl->add_task(lambda);
-    }
+  fut.wait();
-
+}
-    FLUTTER_PLUGIN_EXPORT bool set_camera_ffi(void* const viewer, EntityId asset, const char *nodeName)
+
-    {
+FLUTTER_PLUGIN_EXPORT void
-        std::packaged_task<bool()> lambda([&]
+get_morph_target_name_ffi(void *assetManager, EntityId asset,
-                                          { return set_camera(viewer, asset, nodeName); });
+                          const char *meshName, char *const outPtr, int index) {
-        auto fut = _rl->add_task(lambda);
+  std::packaged_task<void()> lambda([&] {
-        fut.wait();
+    get_morph_target_name(assetManager, asset, meshName, outPtr, index);
-        return fut.get();
+  });
-    }
+  auto fut = _rl->add_task(lambda);
-
+  fut.wait();
-    FLUTTER_PLUGIN_EXPORT void set_bone_animation_ffi(
+}
-        void *assetManager,
+
-        EntityId asset,
+FLUTTER_PLUGIN_EXPORT int
-        const float *const frameData,
+get_morph_target_name_count_ffi(void *assetManager, EntityId asset,
-        int numFrames,
+                                const char *meshName) {
-        int numBones,
+  std::packaged_task<int()> lambda([&] {
-        const char **const boneNames,
+    return get_morph_target_name_count(assetManager, asset, meshName);
-        const char **const meshName,
+  });
-        int numMeshTargets,
+  auto fut = _rl->add_task(lambda);
-        float frameLengthInMs)
+  fut.wait();
-    {
+  return fut.get();
-        std::packaged_task<void()> lambda([&]
+}
-                                          { set_bone_animation(
+
-                                                assetManager, asset, frameData, numFrames, numBones,
+void set_morph_target_weights_ffi(void *const assetManager, EntityId asset,
-                                                boneNames, meshName, numMeshTargets, frameLengthInMs); });
+                                  const char *const entityName,
-        auto fut = _rl->add_task(lambda);
+                                  const float *const morphData,
-        fut.wait();
+                                  int numWeights) {
-    }
+  // TODO
-
+}
-    FLUTTER_PLUGIN_EXPORT void get_morph_target_name_ffi(void *assetManager, EntityId asset, const char *meshName, char *const outPtr, int index)
+
-    {
+FLUTTER_PLUGIN_EXPORT void play_animation_ffi(void *const assetManager,
-        std::packaged_task<void()> lambda([&]
+                                              EntityId asset, int index,
-                                          { get_morph_target_name(assetManager, asset, meshName, outPtr, index); });
+                                              bool loop, bool reverse,
-        auto fut = _rl->add_task(lambda);
+                                              bool replaceActive,
-        fut.wait();
+                                              float crossfade) {
-    }
+  std::packaged_task<void()> lambda([&] {
-
+    play_animation(assetManager, asset, index, loop, reverse, replaceActive,
-    FLUTTER_PLUGIN_EXPORT int get_morph_target_name_count_ffi(void *assetManager, EntityId asset, const char *meshName)
+                   crossfade);
-    {
+  });
-        std::packaged_task<int()> lambda([&]
+  auto fut = _rl->add_task(lambda);
-                                         { return get_morph_target_name_count(assetManager, asset, meshName); });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+
-        return fut.get();
+FLUTTER_PLUGIN_EXPORT void set_animation_frame_ffi(void *const assetManager,
-    }
+                                                   EntityId asset,
-
+                                                   int animationIndex,
-    void set_morph_target_weights_ffi(
+                                                   int animationFrame) {
-        void* const assetManager,
+  std::packaged_task<void()> lambda([&] {
-        EntityId asset,
+    set_animation_frame(assetManager, asset, animationIndex, animationFrame);
-        const char *const entityName,
+  });
-        const float *const morphData,
+  auto fut = _rl->add_task(lambda);
-        int numWeights)
+  fut.wait();
-    {
+}
-        // TODO
+
-    }
+FLUTTER_PLUGIN_EXPORT void stop_animation_ffi(void *const assetManager,
-
+                                              EntityId asset, int index) {
-    FLUTTER_PLUGIN_EXPORT void play_animation_ffi(void* const assetManager, EntityId asset, int index, bool loop, bool reverse, bool replaceActive, float crossfade)
+  std::packaged_task<void()> lambda(
-    {
+      [&] { stop_animation(assetManager, asset, index); });
-        std::packaged_task<void()> lambda([&]
+  auto fut = _rl->add_task(lambda);
-                                          { play_animation(assetManager, asset, index, loop, reverse, replaceActive, crossfade); });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+
-    }
+FLUTTER_PLUGIN_EXPORT int get_animation_count_ffi(void *const assetManager,
-    
+                                                  EntityId asset) {
-    FLUTTER_PLUGIN_EXPORT void set_animation_frame_ffi(void* const assetManager, EntityId asset, int animationIndex, int animationFrame)
+  std::packaged_task<int()> lambda(
-    {
+      [&] { return get_animation_count(assetManager, asset); });
-        std::packaged_task<void()> lambda([&]
+  auto fut = _rl->add_task(lambda);
-                                          { set_animation_frame(assetManager, asset, animationIndex, animationFrame); });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+  return fut.get();
-        fut.wait();
+}
-    }
+FLUTTER_PLUGIN_EXPORT void get_animation_name_ffi(void *const assetManager,
-    
+                                                  EntityId asset,
-    FLUTTER_PLUGIN_EXPORT void stop_animation_ffi(void* const assetManager, EntityId asset, int index)
+                                                  char *const outPtr,
-    {
+                                                  int index) {
-        std::packaged_task<void()> lambda([&]
+  std::packaged_task<void()> lambda(
-                                          { stop_animation(assetManager, asset, index); });
+      [&] { get_animation_name(assetManager, asset, outPtr, index); });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-    }
+}
-    
+
-    FLUTTER_PLUGIN_EXPORT int get_animation_count_ffi(void* const assetManager, EntityId asset)
+FLUTTER_PLUGIN_EXPORT void set_post_processing_ffi(void *const viewer,
-    {
+                                                   bool enabled) {
-        std::packaged_task<int()> lambda([&]
+  std::packaged_task<void()> lambda(
-                                         { return get_animation_count(assetManager, asset); });
+      [&] { set_post_processing(viewer, enabled); });
-        auto fut = _rl->add_task(lambda);
+  auto fut = _rl->add_task(lambda);
-        fut.wait();
+  fut.wait();
-        return fut.get();
+}
-    }
+
-    FLUTTER_PLUGIN_EXPORT void get_animation_name_ffi(void* const assetManager, EntityId asset, char *const outPtr, int index)
+FLUTTER_PLUGIN_EXPORT void pick_ffi(void *const viewer, int x, int y,
-    {
+                                    EntityId *entityId) {
-        std::packaged_task<void()> lambda([&] {
+  std::packaged_task<void()> lambda([&] { pick(viewer, x, y, entityId); });
-            get_animation_name(assetManager, asset, outPtr, index);
+  auto fut = _rl->add_task(lambda);
-        });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+}
-        fut.wait();
+
-    }
+FLUTTER_PLUGIN_EXPORT const char *
-
+get_name_for_entity_ffi(void *const assetManager, const EntityId entityId) {
-    FLUTTER_PLUGIN_EXPORT void set_post_processing_ffi(void* const viewer, bool enabled) {
+  std::packaged_task<const char *()> lambda(
-        std::packaged_task<void()> lambda([&] {
+      [&] { return get_name_for_entity(assetManager, entityId); });
-            set_post_processing(viewer, enabled);
+  auto fut = _rl->add_task(lambda);
-        });
+  fut.wait();
-        auto fut = _rl->add_task(lambda);
+  return fut.get();
-        fut.wait();
+}
-    }
+
-
+FLUTTER_PLUGIN_EXPORT void ios_dummy_ffi() { Log("Dummy called"); }
-    FLUTTER_PLUGIN_EXPORT void pick_ffi(void* const viewer, int x, int y, EntityId* entityId) {
-        std::packaged_task<void()> lambda([&] {
-            pick(viewer, x, y, entityId);
-        });
-        auto fut = _rl->add_task(lambda);
-        fut.wait();
-    }
-
-    FLUTTER_PLUGIN_EXPORT const char* get_name_for_entity_ffi(void* const assetManager, const EntityId entityId) { 
-        std::packaged_task<const char*()> lambda([&] {
-            return get_name_for_entity(assetManager, entityId);
-        });
-        auto fut = _rl->add_task(lambda);
-        fut.wait();
-        return fut.get();
-    }
-
-
-    FLUTTER_PLUGIN_EXPORT void ios_dummy_ffi() {
-        Log("Dummy called");
-    }
 }

lib/filament_controller.dart

@@ -8,11 +8,18 @@ typedef FilamentEntity = int;
 
 enum ToneMapper { ACES, FILMIC, LINEAR }
 
+class TextureDetails { 
+  final int textureId;
+  final int width;
+  final int height;
+
+  TextureDetails({required this.textureId, required this.width, required this.height});
+}
+
 abstract class FilamentController {
   // the current target size of the viewport, in logical pixels
   ui.Size size = ui.Size.zero;
 
-  Stream<int?> get textureId;
   Future get isReadyForScene;
 
   ///
@@ -54,6 +61,7 @@ abstract class FilamentController {
   ///
   Future destroyViewer();
 
+
   ///
   /// Destroys the backing texture. You probably want to call [destroy] instead of this; this is exposed mostly for lifecycle changes which are handled by FilamentWidget.
   ///
@@ -71,13 +79,13 @@ abstract class FilamentController {
   /// 5) The FilamentWidget will replace the empty Container with a Texture widget
   /// If you need to wait until a FilamentViewer has been created, [await] the [isReadyForScene] Future.
   ///
-  Future createViewer(int width, int height);
+  Future<TextureDetails> createViewer(int width, int height);
 
   ///
   /// Resize the viewport & backing texture.
   /// This is called by FilamentWidget; you shouldn't need to invoke this manually.
   ///
-  Future resize(int width, int height, {double scaleFactor = 1.0});
+  Future<TextureDetails> resize(int width, int height, {double scaleFactor = 1.0});
 
   ///
   /// Set the background image to [path] (which should have a file extension .png, .jpg, or .ktx).

lib/filament_controller_ffi.dart

@@ -11,14 +11,13 @@ import 'package:polyvox_filament/generated_bindings.dart';
 
 const FilamentEntity _FILAMENT_ASSET_ERROR = 0;
 
+
 class FilamentControllerFFI extends FilamentController {
   late MethodChannel _channel = MethodChannel("app.polyvox.filament/event");
 
   double _pixelRatio = 1.0;
 
   int? _textureId;
-  final _textureIdController = StreamController<int?>.broadcast();
-  Stream<int?> get textureId => _textureIdController.stream;
 
   Completer _isReadyForScene = Completer();
   Future get isReadyForScene => _isReadyForScene.future;
@@ -105,20 +104,21 @@ class FilamentControllerFFI extends FilamentController {
 
   @override
   Future destroyTexture() async {
+    if(_textureId != null) {
+      throw Exception("No texture available");
+    }
     print("Destroying texture");
     // we need to flush all references to the previous texture ID before calling destroy, otherwise the Texture widget will attempt to render a non-existent texture and crash.
     // however, this is not a synchronous stream, so we need to ensure the Texture widget has been removed from the hierarchy before destroying
     _textureId = null;
-    _textureIdController.add(null);
+    await _channel.invokeMethod("destroyTexture", _textureId!);
-
-    await _channel.invokeMethod("destroyTexture");
     print("Texture destroyed");
   }
 
   ///
   /// Called by `FilamentWidget`. You do not need to call this yourself.
   ///
-  Future createViewer(int width, int height) async {
+  Future<TextureDetails> createViewer(int width, int height) async {
     if (_viewer != null) {
       throw Exception(
           "Viewer already exists, make sure you call destroyViewer first");
@@ -133,8 +133,6 @@ class FilamentControllerFFI extends FilamentController {
       throw Exception("Failed to get resource loader");
     }
 
-    print("Using loader ${loader.address}");
-
     size = ui.Size(width * _pixelRatio, height * _pixelRatio);
 
     print("Creating viewer with size $size");
@@ -195,45 +193,99 @@ class FilamentControllerFFI extends FilamentController {
 
     _assetManager = _lib.get_asset_manager(_viewer!);
 
-    _textureIdController.add(_textureId);
-
     _isReadyForScene.complete(true);
+    return TextureDetails(textureId: _textureId!, width: width, height:height);
   }
 
   ///
-  /// I'm not exactly sure how to resize the backing textures on all platforms.
+  /// When a FilamentWidget is resized, it will call [resize]. This method will tear down/recreate the swapchain and propagate a new texture ID back to the FilamentWidget.
-  /// So for now, I'm sticking with the safe option when the widget is resized: destroying the swapchain, recreating the textures, and creating a new swapchain.
+  /// For "once-off" resizes, this is fine.
+  /// However, this can be problematic for consecutive resizes (e.g. dragging to expand/contract the parent window on desktop, or animating the size of the FilamentWidget itself).
+  /// It is too expensive to recreate the swapchain multiple times per second.
+  /// We therefore add a timer to FilamentWidget so that the call to [resize] is delayed (e.g. 50ms).
+  /// Any subsequent resizes before the delay window elapses will cancel the earlier call.
   /// 
+  ///  The overall process looks like this:
+  /// 1) the window is resized
+  /// 2) (Windows only) PixelBufferTexture is requested to provide a new pixel buffer with a new size, and we return an empty texture
+  /// 3) After Xms, [resize] is invoked
+  /// 4) the viewer is instructed to stop rendering (synchronous)
+  /// 5) the existing Filament swapchain is destroyed (synchronous)
+  /// 6) the Flutter texture is unregistered
+  ///   a) this is asynchronous, but
+  ///   b) *** SEE NOTE BELOW ON WINDOWS *** by passing the method channel result through to the callback, we make this synchronous from the Flutter side,
+  //    c) in this async callback, the glTexture is destroyed
+  /// 7) a new Flutter/OpenGL texture is created (synchronous)
+  /// 8) a new swapchain is created (synchronous)
+  /// 9) if the viewer was rendering prior to the resize, the viewer is instructed to recommence rendering
+  /// 10) the new texture ID is pushed to the FilamentWidget
+  /// 11) the FilamentWidget updates the Texture widget with the new texture.
+  /// 
+  /// #### (Windows-only) ############################################################
+  /// # As soon as the widget/window is resized, the PixelBufferTexture will be 
+  /// # requested to provide a new pixel buffer for the new size.
+  /// # Even with zero delay to the call to [resize], this will be triggered *before* 
+  /// # we have had a chance to anything else (like tear down the swapchain).
+  /// # On the backend, we deal with this by simply returning an empty texture as soon 
+  /// # as the size changes, and will rely on the followup call to [resize] to actually
+  /// # destroy/recreate the pixel buffer and Flutter texture.
+  /// 
+  /// NOTE RE ASYNC CALLBACK
+  /// # The bigger problem is a race condition when resize is called multiple times in quick succession (e.g dragging to resize on Windows).
+  /// # It looks like occasionally, the backend OpenGL texture is being destroyed while its corresponding swapchain is still active, causing a crash.
+  /// # I'm not exactly sure how/where this is occurring, but something clearly isn't synchronized between destroy_swap_chain_ffi and 
+  /// # the asynchronous callback passed to FlutterTextureRegistrar::UnregisterTexture. 
+  /// # Theoretically this could occur if resize_2 starts before resize_1 completes, i.e.
+  /// # 1) resize_1 destroys swapchain/texture and creates new texture
+  /// # 2) resize_2 destroys swapchain/texture
+  /// # 3) resize_1 creates new swapchain but texture isn't available, ergo crash
+  /// # 
+  /// # I don't think this should happen if:
+  /// # 1) we add a flag on the Flutter side to ensure only one call to destroy/recreate the swapchain/texture is active at any given time, and
+  /// # 2) on the Flutter side, we are sure that calling destroyTexture only returns once the async callback on the native side has completed. 
+  /// # For (1), checking if textureId is null at the entrypoint should be sufficient.
+  /// # For (2), we invoke flutter::MethodResult<flutter::EncodableValue>->Success in the UnregisterTexture callback.
+  /// # 
+  /// # Maybe (2) doesn't actually make Flutter wait?
+  /// #
+  /// # The other possibility is that both (1) and (2) are fine and the issue is elsewhere.
+  /// #
+  /// # Either way, the current solution is to basically setup a double-buffer on resize.
+  /// # When destroyTexture is called, the active texture isn't destroyed yet, it's only marked as inactive.
+  /// # On subsequent calls to destroyTexture, the inactive texture is destroyed.
+  /// # This seems to work fine.
+  /// 
+  /// # Another option is to only use a single large (e.g. 4k) texture and simply crop whenever a resize is requested.
+  /// # This might be preferable for other reasons (e.g. don't need to destroy/recreate the pixel buffer or swapchain).
+  /// # Given we don't do this on other platforms, I'm OK to stick with the existing solution for the time being.
+  /// ############################################################################
+  /// 
+
+  ///
+  ///
+  /// Other options:
+  /// 1) never destroy the texture, simply allocate a large (4k?) texture and crop as needed
+  /// 2) double-buffering?
   @override
-  Future resize(int width, int height, {double scaleFactor = 1.0}) async {
+  Future<TextureDetails> resize(int width, int height, {double scaleFactor = 1.0}) async {
     if (_textureId == null) {
-      print("No texture created, ignoring call to resize.");
+      throw Exception("No texture created, ignoring call to resize.");
-      return;
     }
+    var textureId = _textureId;
+    _textureId = null;
   
-    if (_resizing) {
+    _lib.set_rendering_ffi(_viewer!, false);
-      print("Resize currently underway, ignoring");
-      return;
-    }
-
-    bool wasRendering = _rendering;
-    if (_viewer != null && _rendering) {
-      await setRendering(false);
-    }
-
-    _resizing = true;
     
     if (_viewer != null) {
       _lib.destroy_swap_chain_ffi(_viewer!);
     }
-    await destroyTexture();
+
+    await _channel.invokeMethod("destroyTexture", textureId);
+
     size = ui.Size(width * _pixelRatio, height * _pixelRatio);
 
     var textures =
         await _channel.invokeMethod("createTexture", [size.width, size.height]);
-    print("Created new texture");
-    var flutterTextureId = textures[0];
-    _textureId = flutterTextureId;
 
     // void* on iOS (pointer to pixel buffer), void* on Android (pointer to native window), null on Windows/macOS
     var surfaceAddress = textures[1] as int? ?? 0;
@@ -256,11 +308,10 @@ class FilamentControllerFFI extends FilamentController {
     _lib.update_viewport_and_camera_projection_ffi(
         _viewer!, size.width.toInt(), size.height.toInt(), 1.0);
 
-    _textureIdController.add(_textureId);
+    await setRendering(_rendering);
-    _resizing = false;
+    _textureId = textures[0];
-    if (wasRendering) {
+
-      setRendering(true);
+    return TextureDetails(textureId: _textureId!, width: width, height:height);
-    }
   }
 
   @override

lib/filament_controller_method_channel.dart

@@ -91,7 +91,8 @@ class FilamentControllerMethodChannel extends FilamentController {
   /// 3) Initially, this widget will only contain an empty Container. After the first frame is rendered, the widget itself will automatically call [createViewer] with the width/height from its constraints
   /// 4) The FilamentWidget will replace the empty Container with the Texture widget.
   ///
-  Future createViewer(int width, int height) async {
+  Future<TextureDetails> createViewer(int width, int height) async {
+    throw Exception();
     if (_viewer != null) {
       throw Exception(
           "Viewer already exists, make sure you call destroyViewer first");
@@ -119,7 +120,9 @@ class FilamentControllerMethodChannel extends FilamentController {
 
   bool _resizing = false;
 
-  Future resize(int width, int height, {double scaleFactor = 1.0}) async {
+
+  Future<TextureDetails> resize(int width, int height, {double scaleFactor = 1.0}) async {
+    throw Exception();
     _resizing = true;
     _textureId = await _channel.invokeMethod(
         "resize", [width * _pixelRatio, height * _pixelRatio, scaleFactor]);

lib/widgets/filament_widget.dart

@@ -56,10 +56,8 @@ class FilamentWidget extends StatefulWidget {
   /// The default is a solid red Container, intentionally chosen to make it clear that there will be at least one frame where the Texture widget is not being rendered.
   ///
   final Widget? initial;
-  final void Function()? onResize;
 
-  const FilamentWidget(
+  const FilamentWidget({Key? key, required this.controller, this.initial})
-      {Key? key, required this.controller, this.onResize, this.initial})
       : super(key: key);
 
   @override
@@ -67,23 +65,21 @@ class FilamentWidget extends StatefulWidget {
 }
 
 class _FilamentWidgetState extends State<FilamentWidget> {
-  StreamSubscription? _textureIdListener;
+  TextureDetails? _textureDetails;
-  int? _textureId;
 
   late final AppLifecycleListener _listener;
   AppLifecycleState? _lastState;
 
-  bool _resizing = false;
-
   String? _error;
 
-  Timer? _resizeTimer;
+  int? _width;
+  int? _height;
 
   void _handleStateChange(AppLifecycleState state) async {
     switch (state) {
       case AppLifecycleState.detached:
         print("Detached");
-        _textureId = null;
+        _textureDetails = null;
 
         await widget.controller.destroyViewer();
         await widget.controller.destroyTexture();
@@ -91,7 +87,7 @@ class _FilamentWidgetState extends State<FilamentWidget> {
       case AppLifecycleState.hidden:
         print("Hidden");
         if (Platform.isIOS) {
-          _textureId = null;
+          _textureDetails = null;
           await widget.controller.destroyViewer();
           await widget.controller.destroyTexture();
         }
@@ -104,12 +100,16 @@ class _FilamentWidgetState extends State<FilamentWidget> {
         break;
       case AppLifecycleState.resumed:
         print("Resumed");
-        if (_textureId == null) {
+        if (!Platform.isWindows) {
-          var size = ((context.findRenderObject()) as RenderBox).size;
+          if (_textureDetails == null) {
-          print("Size after resuming : $size");
+            var size = ((context.findRenderObject()) as RenderBox).size;
-          await widget.controller
+            print("Size after resuming : $size");
-              .createViewer(size.width.toInt(), size.height.toInt());
+            _height = size.height.ceil();
-          print("Created viewer Size after resuming");
+            _width = size.width.ceil();
+            await widget.controller
+                .createViewer(_width!, _height!);
+            print("Created viewer Size after resuming");
+          }
         }
         break;
     }
@@ -130,9 +130,12 @@ class _FilamentWidgetState extends State<FilamentWidget> {
         await Future.delayed(Duration(seconds: 2));
       }
       var size = ((context.findRenderObject()) as RenderBox).size;
-
+      _width = size.width.ceil();
+      _height = size.height.ceil();
       try {
-        await widget.controller.createViewer(size.width.toInt(), size.height.toInt());
+        _textureDetails = await widget.controller
+            .createViewer(_width!, _height!);
+        
       } catch (err) {
         setState(() {
           _error = err.toString();
@@ -140,28 +143,20 @@ class _FilamentWidgetState extends State<FilamentWidget> {
       }
     });
 
-    _textureIdListener = widget.controller.textureId.listen((int? textureId) {
-      var size = ((context.findRenderObject()) as RenderBox).size;
-      print(
-          "Received new texture ID $textureId at size $size (current textureID  $_textureId)");
-      setState(() {
-        _textureId = textureId;
-      });
-    });
-
     super.initState();
   }
 
   @override
   void dispose() {
-    _textureIdListener?.cancel();
     _listener.dispose();
-    _resizeTimer?.cancel();
     super.dispose();
   }
 
+  Timer? _resizeTimer;
+
   @override
   Widget build(BuildContext context) {
+    // if an error was encountered in creating a viewer, display the error message and don't even try to display a Texture widget.
     if (_error != null) {
       return Container(
           color: Colors.white,
@@ -170,51 +165,51 @@ class _FilamentWidgetState extends State<FilamentWidget> {
             Text(_error!)
           ]));
     }
-    return LayoutBuilder(builder: ((context, constraints) {
+
-      if (_textureId == null) {
+    // if no texture ID is available, display the [initial] widget (solid red by default)
-        return widget.initial ?? Container(color: Colors.red);
+    late Widget content;
-      }
+
-      var texture = Texture(
+    if ( _textureDetails == null || _textureDetails!.height != _height || _textureDetails!.width != _width) {
-        key: ObjectKey("texture_$_textureId"),
+      content = widget.initial ?? Container(color: Colors.red);
-        textureId: _textureId!,
+    } else {
+      content = Texture(
+        key: ObjectKey("texture_${_textureDetails!.textureId}"),
+        textureId: _textureDetails!.textureId,
         filterQuality: FilterQuality.none,
+        freeze: false,
       );
-      return SizedBox(
+    }
-          height: constraints.maxHeight,
-          width: constraints.maxWidth,
-          child: ResizeObserver(
-              onResized: (Size oldSize, Size newSize) async {
-                WidgetsBinding.instance.addPostFrameCallback((_) async {
-                  _resizeTimer?.cancel();
 
-                  _resizeTimer = Timer(Duration(milliseconds: 500), () async {
+    // see [FilamentControllerFFI.resize] for an explanation of how we deal with resizing
-                    // setState(() {
+    return ResizeObserver(
-                    //   _resizing = true;
+        onResized: (Size oldSize, Size newSize) async {
-                    // });
 
-                    // TODO - we could snapshot the widget to display while we resize?
+          _resizeTimer?.cancel();
 
-                    print("Resizing to $newSize");
+          WidgetsBinding.instance.addPostFrameCallback((_) {
-                    // await widget.controller
+            _resizeTimer = Timer(const Duration(milliseconds:50), () async {
-                    //     .resize(newSize.width.toInt(), newSize.height.toInt());
+              var newWidth = newSize.width.ceil();
-                    // WidgetsBinding.instance.addPostFrameCallback((_) async {
+              var newHeight = newSize.height.ceil();
-                    //   setState(() {
+              _textureDetails = await widget.controller
-                    //     _resizing = false;
+                  .resize(newWidth, newHeight);
-                    //     widget.onResize?.call();
+              WidgetsBinding.instance.addPostFrameCallback((_) {
-                    //   });
+                setState(() {
-                    // });
+                  _width = newWidth;
-                  });
+                  _height = newHeight;
                 });
-              },
+              });
-              child: _resizing
+            });
-                  ? Container()
+          });
-                  : Platform.isLinux || Platform.isWindows
+        },
-                      ? Transform(
+        child: Stack(children: [
-                          alignment: Alignment.center,
+          Positioned.fill(
-                          transform: Matrix4.rotationX(
+              child: Platform.isLinux || Platform.isWindows
-                              pi), // TODO - this rotation is due to OpenGL texture coordinate working in a different space from Flutter, can we move this to the C++ side somewhere?
+                  ? Transform(
-                          child: texture)
+                      alignment: Alignment.center,
-                      : texture));
+                      transform: Matrix4.rotationX(
-    }));
+                          pi), // TODO - this rotation is due to OpenGL texture coordinate working in a different space from Flutter, can we move this to the C++ side somewhere?
+                      child: content)
+                  : content)
+        ]));
   }
 }

windows/CMakeLists.txt

@@ -12,6 +12,7 @@ set(PLUGIN_NAME "polyvox_filament_plugin")
 list(APPEND PLUGIN_SOURCES
   "polyvox_filament_plugin.cpp"
   "polyvox_filament_plugin.h"
+  "opengl_texture_buffer.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../ios/src/AssetManager.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../ios/src/FilamentViewer.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/../ios/src/PolyvoxFilamentApi.cpp"
@@ -69,8 +70,8 @@ if(USE_ANGLE)
 else()
   list(APPEND GL_LIBS
     bluegl
-    bluevk
+    # bluevk
-    vkshaders
+    # vkshaders
     opengl32
   )
   set(ANGLE_OR_OPENGL_DIR opengl)

windows/opengl_texture_buffer.cpp

@@ -0,0 +1,129 @@
+#include "opengl_texture_buffer.h"
+
+#include <flutter/method_channel.h>
+#include <flutter/plugin_registrar_windows.h>
+#include <flutter/standard_method_codec.h>
+#include <flutter/texture_registrar.h>
+
+#include <thread>
+
+namespace polyvox_filament {
+
+void _release_callback(void *releaseContext) {
+  // ((OpenGLTextureBuffer*)releaseContext)->unlock();
+}
+
+OpenGLTextureBuffer::OpenGLTextureBuffer(
+    flutter::PluginRegistrarWindows *pluginRegistrar,
+    flutter::TextureRegistrar *textureRegistrar,
+    std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result,
+    uint32_t width, uint32_t height, HGLRC context,
+    std::shared_ptr<std::mutex> renderMutex)
+    : _pluginRegistrar(pluginRegistrar), _textureRegistrar(textureRegistrar),
+      _width(width), _height(height), _context(context),
+      _renderMutex(renderMutex) {
+
+  HWND hwnd = _pluginRegistrar->GetView()->GetNativeWindow();
+
+  HDC whdc = GetDC(hwnd);
+
+  if (!_context || !wglMakeCurrent(whdc, _context)) {
+    result->Error("ERROR", "Failed to switch OpenGL context in constructor.");
+    return;
+  }
+
+  glGenTextures(1, &glTextureId);
+
+  if (glTextureId == 0) {
+    result->Error("ERROR", "Failed to generate texture, OpenGL err was %d",
+                  glGetError());
+    return;
+  }
+
+  glBindTexture(GL_TEXTURE_2D, glTextureId);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, _width, _height, 0, GL_RGBA,
+               GL_UNSIGNED_BYTE, 0);
+
+  GLenum err = glGetError();
+
+  if (err != GL_NO_ERROR) {
+    result->Error("ERROR", "Failed to generate texture, GL error was %d", err);
+    return;
+  }
+  wglMakeCurrent(NULL, NULL);
+
+  pixelBuffer = std::make_unique<FlutterDesktopPixelBuffer>();
+  pixelData.reset(new uint8_t[_width * _height * 4]);
+
+  pixelBuffer->buffer = pixelData.get();
+  pixelBuffer->width = size_t(_width);
+  pixelBuffer->height = size_t(_height);
+  pixelBuffer->release_callback = _release_callback;
+  pixelBuffer->release_context = this;
+
+  std::cout << "Created initial pixel data/buffer of size " << _width << "x"
+            << _height << std::endl;
+
+  texture =
+      std::make_unique<flutter::TextureVariant>(flutter::PixelBufferTexture(
+          [=](size_t width,
+              size_t height) -> const FlutterDesktopPixelBuffer * {
+            if (width != this->_width || height != this->_height) {
+              std::cout << "Front-end widget has been resized, you need to "
+                           "teardown/rebuild the swapchain. This pixel buffer "
+                           "will be discarded."
+                        << std::endl;
+              return nullptr;
+            }
+            uint8_t *data = (uint8_t *)pixelData.get();
+
+            if (!_context || !wglMakeCurrent(whdc, _context)) {
+              std::cout << "Failed to switch OpenGL context in callback."
+                        << std::endl;
+            } else {
+              // It seems there's at least 1 frame delay between resizing a
+              // front-end widget and the layout operation being performed on
+              // Windows. I haven't found a way to guarantee that we can resize
+              // the OpenGL texture before the pixel buffer callback here. (If
+              // you can find/suggest a way, please let me know). This means we
+              // need to manually check that the requested size matches the
+              // current size of our GL texture, and return an empty pixel
+              // buffer if not.
+              glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);
+
+              GLenum err = glGetError();
+
+              if (err != GL_NO_ERROR) {
+                if (err == GL_INVALID_OPERATION) {
+                  std::cout << "Invalid op" << std::endl;
+                } else if (err == GL_INVALID_VALUE) {
+                  std::cout << "Invalid value" << std::endl;
+                } else if (err == GL_OUT_OF_MEMORY) {
+                  std::cout << "Out of mem" << std::endl;
+                } else if (err == GL_INVALID_ENUM) {
+                  std::cout << "Invalid enum" << std::endl;
+                } else {
+                  std::cout << "Unknown error" << std::endl;
+                }
+              }
+              wglMakeCurrent(NULL, NULL);
+            }
+            pixelBuffer->buffer = pixelData.get();
+            return pixelBuffer.get();
+          }));
+
+  flutterTextureId = textureRegistrar->RegisterTexture(texture.get());
+  std::cout << "Registered Flutter texture ID " << flutterTextureId
+            << std::endl;
+  std::vector<flutter::EncodableValue> resultList;
+  resultList.push_back(flutter::EncodableValue(flutterTextureId));
+  resultList.push_back(flutter::EncodableValue((int64_t) nullptr));
+  resultList.push_back(flutter::EncodableValue(glTextureId));
+  result->Success(resultList);
+}
+
+OpenGLTextureBuffer::~OpenGLTextureBuffer() {}
+
+} // namespace polyvox_filament

windows/opengl_texture_buffer.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#ifndef _OPENGL_TEXTURE_BUFFER_H 
+#define _OPENGL_TEXTURE_BUFFER_H
+
+#include <mutex>
+
+#include <flutter/texture_registrar.h>
+#include <flutter/method_channel.h>
+#include <flutter/plugin_registrar_windows.h>
+
+#include "GL/GL.h"
+#include "GL/GLu.h"
+#include "GL/wglext.h"
+
+#include <Windows.h>
+#include <wrl.h>
+
+typedef uint32_t GLuint;
+
+namespace polyvox_filament {
+
+class OpenGLTextureBuffer {
+  public:
+
+    OpenGLTextureBuffer(
+        flutter::PluginRegistrarWindows* pluginRegistrar,
+        flutter::TextureRegistrar* textureRegistrar,
+        std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result,
+        uint32_t width,
+        uint32_t height,
+        HGLRC context,
+        std::shared_ptr<std::mutex> renderMutex);
+    
+    ~OpenGLTextureBuffer();
+    GLuint glTextureId = 0;
+    int64_t flutterTextureId = 0;
+    std::unique_ptr<FlutterDesktopPixelBuffer> pixelBuffer;
+    std::unique_ptr<uint8_t> pixelData;
+    std::unique_ptr<flutter::TextureVariant> texture;
+  
+  private:
+    flutter::PluginRegistrarWindows* _pluginRegistrar;
+    flutter::TextureRegistrar* _textureRegistrar;
+    uint32_t _width = 0;
+    uint32_t _height = 0;
+    HGLRC _context = NULL;
+    bool logged = false;
+    std::shared_ptr<std::mutex> _renderMutex;
+};
+
+}
+#endif // _OPENGL_TEXTURE_BUFFER_H 

windows/polyvox_filament_plugin.cpp

@@ -33,10 +33,6 @@
 #include "PlatformANGLE.h"
 #endif 
 
-#include "GL/GL.h"
-#include "GL/GLu.h"
-#include "GL/wglext.h"
-
 #include <Windows.h>
 #include <wrl.h>
 
@@ -83,7 +79,7 @@ ResourceBuffer PolyvoxFilamentPlugin::loadResource(const char *name) {
       name_str = name_str.substr(8);
     }
 
-    TCHAR pBuf[256];
+    TCHAR pBuf[512];
     size_t len = sizeof(pBuf);
     int bytes = GetModuleFileName(NULL, pBuf, len);
     std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>> converter;
@@ -145,7 +141,10 @@ void PolyvoxFilamentPlugin::RenderCallback() {
                                     _internalD3DTexture2D.Get());
   _D3D11DeviceContext->Flush();
   #endif
-  _textureRegistrar->MarkTextureFrameAvailable(_flutterTextureId);
+  std::lock_guard<std::mutex> guard(*(_renderMutex.get()));
+  if (_active) {
+      _textureRegistrar->MarkTextureFrameAvailable(_active->flutterTextureId);
+  }
 }
 
 #ifdef USE_ANGLE
@@ -293,8 +292,9 @@ bool PolyvoxFilamentPlugin::MakeD3DTexture(uint32_t width, uint32_t height,std::
 }
 #else
 bool PolyvoxFilamentPlugin::MakeOpenGLTexture(uint32_t width, uint32_t height,std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
+
   HWND hwnd = _pluginRegistrar->GetView()
-                  ->GetNativeWindow();;
+                  ->GetNativeWindow();
 
   HDC whdc = GetDC(hwnd);
   if (whdc == NULL) {
@@ -302,146 +302,99 @@ bool PolyvoxFilamentPlugin::MakeOpenGLTexture(uint32_t width, uint32_t height,st
     return false;
   }
 
-  PIXELFORMATDESCRIPTOR pfd = {
+  if(!_renderMutex.get()) {
-        sizeof(PIXELFORMATDESCRIPTOR),
+    _renderMutex = std::make_shared<std::mutex>();
-        1,
+  }
-        PFD_DRAW_TO_BITMAP | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,    // Flags
-        PFD_TYPE_RGBA,        // The kind of framebuffer. RGBA or palette.
-        32,                   // Colordepth of the framebuffer.
-        0, 0, 0, 0, 0, 0,
-        0,
-        0,
-        0,
-        0, 0, 0, 0,
-        32,                   // Number of bits for the depthbuffer
-        0,                    // Number of bits for the stencilbuffer
-        0,                    // Number of Aux buffers in the framebuffer.
-        PFD_MAIN_PLANE,
-        0,
-        0, 0, 0
-    };
 
-  int pixelFormat = ChoosePixelFormat(whdc, &pfd);
-  SetPixelFormat(whdc, pixelFormat, &pfd);
 
-  // We need a tmp context to retrieve and call wglCreateContextAttribsARB.
+  // we need a single context (since this will be passed to the renderer)
-  HGLRC tempContext = wglCreateContext(whdc);
+  // if this is the first time we are attempting to create a texture, let's create the context
-  if (!wglMakeCurrent(whdc, tempContext)) {
+  if(_context == NULL) {
-    result->Error("ERROR", "Failed to acquire temporary context", nullptr);
+     
+      std::cout << "No GL context exists, creating" << std::endl;
+
+      PIXELFORMATDESCRIPTOR pfd = {
+            sizeof(PIXELFORMATDESCRIPTOR),
+            1,
+            PFD_DRAW_TO_BITMAP | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER,    // Flags
+            PFD_TYPE_RGBA,        // The kind of framebuffer. RGBA or palette.
+            32,                   // Colordepth of the framebuffer.
+            0, 0, 0, 0, 0, 0,
+            0,
+            0,
+            0,
+            0, 0, 0, 0,
+            32,                   // Number of bits for the depthbuffer
+            0,                    // Number of bits for the stencilbuffer
+            0,                    // Number of Aux buffers in the framebuffer.
+            PFD_MAIN_PLANE,
+            0,
+            0, 0, 0
+        };
+
+      int pixelFormat = ChoosePixelFormat(whdc, &pfd);
+      SetPixelFormat(whdc, pixelFormat, &pfd);
+
+      // We need a tmp context to retrieve and call wglCreateContextAttribsARB.
+      HGLRC tempContext = wglCreateContext(whdc);
+      if (!wglMakeCurrent(whdc, tempContext)) {
+        result->Error("ERROR", "Failed to acquire temporary context", nullptr);
+      }
+
+      GLenum err = glGetError();
+
+      if(err != GL_NO_ERROR) {
+        result->Error("ERROR", "GL Error @ 455 %d", err);
+        return false;
+      }
+
+      PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = nullptr;
+
+      wglCreateContextAttribs =
+          (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress(
+              "wglCreateContextAttribsARB");
+
+      if (!wglCreateContextAttribs) {
+        result->Error("ERROR", "Failed to resolve wglCreateContextAttribsARB",
+                      nullptr);
+        return false;
+      }
+
+      for (int minor = 5; minor >= 1; minor--) {
+        std::vector<int> mAttribs = {WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
+                                    WGL_CONTEXT_MINOR_VERSION_ARB, minor, 0};
+        _context = wglCreateContextAttribs(whdc, nullptr, mAttribs.data());
+        if (_context) {
+          break;
+        }
+      }
+
+      wglMakeCurrent(NULL, NULL);
+      wglDeleteContext(tempContext);
+
+      if (!_context || !wglMakeCurrent(whdc, _context)) {
+        result->Error("ERROR", "Failed to create OpenGL context.");
+        return false;
+      }
+
+  }
+  
+  if(_active.get()) {
+    result->Error("ERROR", "Texture already exists. You must call destroyTexture before attempting to create a new one.");
     return false;
   } 
 
-  GLenum err = glGetError();
+  _active = std::make_unique<OpenGLTextureBuffer>(
+    _pluginRegistrar, 
+    _textureRegistrar, 
+    std::move(result), 
+    width, 
+    height, 
+    _context, 
+    _renderMutex
+  );
   
-  if(err != GL_NO_ERROR) {
+  return _active->flutterTextureId != -1;
-    result->Error("ERROR", "GL Error @ 455 %d", err);
-    return false;
-  }
-
-  PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = nullptr;
-
-  wglCreateContextAttribs =
-      (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress(
-          "wglCreateContextAttribsARB");
-
-  if (!wglCreateContextAttribs) {
-    result->Error("ERROR", "Failed to resolve wglCreateContextAttribsARB",
-                  nullptr);
-    return false;
-  }
-
-  for (int minor = 5; minor >= 1; minor--) {
-    std::vector<int> mAttribs = {WGL_CONTEXT_MAJOR_VERSION_ARB, 4,
-                                 WGL_CONTEXT_MINOR_VERSION_ARB, minor, 0};
-    _context = wglCreateContextAttribs(whdc, nullptr, mAttribs.data());
-    if (_context) {
-      break;
-    }
-  }
-
-  wglMakeCurrent(NULL, NULL);
-  wglDeleteContext(tempContext);
-
-
-  if (!_context || !wglMakeCurrent(whdc, _context)) {
-    result->Error("ERROR", "Failed to create OpenGL context.");
-    return false;
-  }
-
-  glGenTextures(1, &_glTextureId);
-
-  if(_glTextureId == 0) {
-    result->Error("ERROR", "Failed to generate texture, OpenGL err was %d", glGetError());
-    return false;
-  }
-
-  glBindTexture(GL_TEXTURE_2D, _glTextureId);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
-  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
-  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA,
-               GL_UNSIGNED_BYTE, 0);
-
-  err = glGetError();
-
-  if (err != GL_NO_ERROR) {
-    result->Error("ERROR", "Failed to generate texture, GL error was %d", err);
-    return false;
-  }
-  wglMakeCurrent(NULL, NULL);
-
-  _pixelData.reset(new uint8_t[width * height * 4]);
-  _pixelBuffer = std::make_unique<FlutterDesktopPixelBuffer>();
-  _pixelBuffer->buffer = _pixelData.get();
-
-  _pixelBuffer->width = size_t(width);
-  _pixelBuffer->height = size_t(height);
- 
-  _texture = std::make_unique<flutter::TextureVariant>(flutter::PixelBufferTexture(
-          [=](size_t width,
-              size_t height) -> const FlutterDesktopPixelBuffer * {
-            std::lock_guard<std::mutex> guard(_renderMutex);
-
-            if(!_context || !wglMakeCurrent(whdc, _context)) {
-              std::cout << "Failed to switch OpenGL context." << std::endl;
-            } else if (_glTextureId != 0) {
-              // uint8_t* data = (uint8_t*)_pixelData.get();
-              uint8_t* data = new uint8_t[width*height*4];
-              glBindTexture(GL_TEXTURE_2D, _glTextureId);
-              glGetTexImage(GL_TEXTURE_2D,0,GL_RGBA,GL_UNSIGNED_BYTE,data);
-
-              GLenum err = glGetError();
-
-              if(err != GL_NO_ERROR) {
-                if(err == GL_INVALID_OPERATION) {
-                  std::cout << "Invalid op" << std::endl;
-                } else if(err == GL_INVALID_VALUE) {
-                std::cout << "Invalid value" << std::endl;
-                } else if(err == GL_OUT_OF_MEMORY) {
-                  std::cout << "Out of mem" << std::endl;
-                } else if(err == GL_INVALID_ENUM ) {
-                  std::cout << "Invalid enum" << std::endl;
-                } else {
-                  std::cout << "Unknown error" << std::endl;
-                }
-              }
-              glFinish();
-              _pixelData.reset(data);
-              wglMakeCurrent(NULL, NULL);
-            }
-            _pixelBuffer->buffer = _pixelData.get();
-
-            return _pixelBuffer.get();
-          }));
-
-  _flutterTextureId = _textureRegistrar->RegisterTexture(_texture.get());
-  std::cout << "Registered Flutter texture ID " << _flutterTextureId << std::endl;
-
-  std::vector<flutter::EncodableValue> resultList;
-  resultList.push_back(flutter::EncodableValue(_flutterTextureId));
-  resultList.push_back(flutter::EncodableValue((int64_t)nullptr));
-  resultList.push_back(flutter::EncodableValue(_glTextureId));
-  result->Success(resultList);
-  return true;
 
 }
 #endif 
@@ -467,30 +420,53 @@ void PolyvoxFilamentPlugin::DestroyTexture(
     const flutter::MethodCall<flutter::EncodableValue> &methodCall,
     std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
 
+  const auto *flutterTextureId =
+      std::get_if<int64_t>(methodCall.arguments());
+
+  if(!flutterTextureId) {
+    result->Error("NOT_IMPLEMENTED", "Flutter texture ID must be provided");
+    return;
+  }
+
   #ifdef USE_ANGLE
     // TODO
     result->Error("NOT_IMPLEMENTED", "Method is not implemented %s", methodCall.method_name());
   #else
-    std::lock_guard<std::mutex> guard(_renderMutex);
+    auto sh = std::make_shared<std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>>>(std::move(result));
 
-    HWND hwnd = _pluginRegistrar->GetView()
+    if(!_active) {
-                  ->GetNativeWindow();
+      result->Success("Texture has already been detroyed, ignoring");
-
-    HDC whdc = GetDC(hwnd);
-
-    if(!_context || !wglMakeCurrent(whdc, _context)) {
-      result->Error("CONTEXT", "Failed to switch OpenGL context.", nullptr);
       return;
     }
-    // for now we will just unregister the Flutter texture and delete the GL texture
+
-    // we will leave the pixel data/PixelBufferTexture intact - these will be replaced on the next call to createTexture
+    if(_active->flutterTextureId != *flutterTextureId) {
-    // if we wanted to be militant about cleaning up unused memory we could delete here first
+      result->Error("TEXTURE_MISMATCH", "Specified texture ID is not active");
-    // _textureRegistrar->UnregisterTexture(_flutterTextureId);
+      return;
-    // _flutterTextureId = -1;    
+    }
-    // glDeleteTextures(1, &_glTextureId);
+
-    // _glTextureId = 0;
+    _textureRegistrar->UnregisterTexture(_active->flutterTextureId, [=, 
-    // wglMakeCurrent(NULL, NULL);
+        sharedResult=std::move(sh)
-    result->Success(flutter::EncodableValue(true));
+    ]() {
+
+        if(this->_inactive) {
+
+          HWND hwnd = _pluginRegistrar->GetView()->GetNativeWindow();
+
+          HDC whdc = GetDC(hwnd);
+
+          if (!wglMakeCurrent(whdc, _context)) {
+              std::cout << "Failed to switch OpenGL context in destructor."                << std::endl;
+              // result->Error("CONTEXT", "Failed to switch OpenGL context.", nullptr);
+              return;
+          }
+          glDeleteTextures(1, &this->_inactive->glTextureId);
+          wglMakeCurrent(NULL, NULL);
+        }
+        this->_inactive = std::move(this->_active);
+        auto unique = std::move(*(sharedResult.get()));
+        unique->Success(flutter::EncodableValue(true));
+        std::cout << "Destroyed OpenGLTextureBuffer." << std::endl;
+    });    
   #endif      
 }
 
@@ -524,8 +500,7 @@ void PolyvoxFilamentPlugin::HandleMethodCall(
     #else
       result->Success(flutter::EncodableValue((int64_t)nullptr));
     #endif
-  }
+  } else {
-  else {
     result->Error("NOT_IMPLEMENTED", "Method is not implemented %s", methodCall.method_name());
   }
 }

windows/polyvox_filament_plugin.h

@@ -26,6 +26,8 @@
 #include "GLES2/gl2.h"
 #include "GLES2/gl2ext.h"
 #include "PlatformAngle.h"
+#else
+#include "opengl_texture_buffer.h"
 #endif 
 
 #include "PolyvoxFilamentApi.h"
@@ -54,15 +56,8 @@ public:
 
   std::map<uint32_t, ResourceBuffer> _resources;
 
-  std::unique_ptr<flutter::TextureVariant> _texture = nullptr;
-
-  std::unique_ptr<FlutterDesktopPixelBuffer> _pixelBuffer = nullptr;
-  std::unique_ptr<uint8_t> _pixelData = nullptr;
-
   std::unique_ptr<FlutterDesktopGpuSurfaceDescriptor> _textureDescriptor = nullptr;
 
-  int64_t _flutterTextureId = -1;
-
   #ifdef USE_ANGLE
   // Device
   ID3D11Device* _D3D11Device = nullptr;
@@ -76,11 +71,12 @@ public:
 
   bool MakeD3DTexture(uint32_t width, uint32_t height, std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
   #else 
-  // OpenGL
+  std::shared_ptr<std::mutex> _renderMutex;
-  HGLRC _context = NULL;
+  std::unique_ptr<OpenGLTextureBuffer> _active = nullptr;
-  GLuint _glTextureId = 0;
+  std::unique_ptr<OpenGLTextureBuffer> _inactive = nullptr;
-  std::mutex _renderMutex;
 
+  // shared OpenGLContext
+  HGLRC _context = NULL;
   bool MakeOpenGLTexture(uint32_t width, uint32_t height, std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
   #endif
 
@@ -90,7 +86,6 @@ public:
   void DestroyTexture(
     const flutter::MethodCall<flutter::EncodableValue> &methodCall,
       std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result);
-
   void RenderCallback();
 
   ResourceBuffer loadResource(const char *path);