feat: add capture() function and expose viewportDimensions on ThermionViewer (allows easier saving of captured images to PNG)

thermion_dart/lib/thermion_dart/compatibility/native/thermion_dart.g.dart

@@ -1059,6 +1059,15 @@ external void render_ffi(
   ffi.Pointer<ffi.Void> viewer,
 );
 
+@ffi.Native<
+    ffi.Void Function(ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Uint8>,
+        ffi.Pointer<ffi.NativeFunction<ffi.Void Function()>>)>()
+external void capture_ffi(
+  ffi.Pointer<ffi.Void> viewer,
+  ffi.Pointer<ffi.Uint8> out,
+  ffi.Pointer<ffi.NativeFunction<ffi.Void Function()>> onComplete,
+);
+
 @ffi.Native<FilamentRenderCallback Function(FilamentRenderCallback)>()
 external FilamentRenderCallback make_render_callback_fn_pointer(
   FilamentRenderCallback arg0,

thermion_dart/lib/thermion_dart/thermion_viewer.dart

@@ -1,4 +1,5 @@
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:thermion_dart/thermion_dart/scene.dart';
 import 'package:vector_math/vector_math_64.dart';
@@ -19,11 +20,11 @@ enum LightType {
   SPOT,
 }
 
-enum ShadowType { 
-    PCF,        //!< percentage-closer filtered shadows (default)
-    VSM,        //!< variance shadows
-    DPCF,       //!< PCF with contact hardening simulation
-    PCSS,       //!< PCF with soft shadows and contact hardening
+enum ShadowType {
+  PCF, //!< percentage-closer filtered shadows (default)
+  VSM, //!< variance shadows
+  DPCF, //!< PCF with contact hardening simulation
+  PCSS, //!< PCF with soft shadows and contact hardening
 }
 
 // copied from filament/backened/DriverEnums.h
@@ -57,6 +58,11 @@ abstract class ThermionViewer {
   
   Future<bool> get initialized;
 
+  ///
+  /// The current dimensions of the viewport (in physical pixels).
+  ///
+  late (double, double) viewportDimensions;
+
   ///
   /// The result(s) of calling [pick] (see below).
   /// This may be a broadcast stream, so you should ensure you have subscribed to this stream before calling [pick].
@@ -79,6 +85,12 @@ abstract class ThermionViewer {
   ///
   Future render();
 
+  
+  ///
+  /// Render a single frame to the viewport and copy the pixel buffer to [out].
+  ///
+  Future<Uint8List> capture();
+
   ///
   /// Sets the framerate for continuous rendering when [setRendering] is enabled.
   ///
@@ -270,10 +282,9 @@ abstract class ThermionViewer {
       {List<String>? targetMeshNames});
 
   ///
-  /// Clear all current morph animations for [entity]. 
+  /// Clear all current morph animations for [entity].
   ///
-  Future clearMorphAnimationData(
-      ThermionEntity entity);
+  Future clearMorphAnimationData(ThermionEntity entity);
 
   ///
   /// Resets all bones in the given entity to their rest pose.
@@ -736,7 +747,6 @@ abstract class ThermionViewer {
   /// Register a callback to be invoked when this viewer is disposed.
   ///
   void onDispose(Future Function() callback);
-  
 }
 
 abstract class AbstractGizmo {

thermion_dart/lib/thermion_dart/thermion_viewer_ffi.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:math';
+import 'dart:typed_data';
 import 'package:animation_tools_dart/animation_tools_dart.dart';
 import 'package:thermion_dart/thermion_dart/compatibility/compatibility.dart';
 import 'package:thermion_dart/thermion_dart/entities/gizmo.dart';
@@ -24,8 +25,6 @@ class ThermionViewerFFI extends ThermionViewer {
 
   double _pixelRatio = 1.0;
 
-  late (double, double) viewportDimensions;
-
   Pointer<Void>? _sceneManager;
 
   Pointer<Void>? _viewer;
@@ -163,6 +162,23 @@ class ThermionViewerFFI extends ThermionViewer {
     render_ffi(_viewer!);
   }
 
+  ///
+  ///
+  ///
+  @override
+  Future<Uint8List> capture() async {
+    final length = this.viewportDimensions.$1.toInt() *
+        this.viewportDimensions.$2.toInt() *
+        4;
+    final out = allocator<Uint8>(length);
+    await withVoidCallback((cb) {
+      capture_ffi(_viewer!, out, cb);
+    });
+    final data = Uint8List.fromList(out.asTypedList(length));
+    allocator.free(out);
+    return data;
+  }
+
   ///
   ///
   ///
@@ -198,7 +214,6 @@ class ThermionViewerFFI extends ThermionViewer {
       await callback.call();
     }
     _onDispose.clear();
-
   }
 
   ///
@@ -602,13 +617,9 @@ class ThermionViewerFFI extends ThermionViewer {
   Future clearMorphAnimationData(ThermionEntity entity) async {
     var meshEntities = await getChildEntities(entity, true);
 
-    for(final childEntity in meshEntities) {
-        clear_morph_animation(
-          _sceneManager!,
-          childEntity);
+    for (final childEntity in meshEntities) {
+      clear_morph_animation(_sceneManager!, childEntity);
     }
-
-
   }
 
   ///
@@ -982,8 +993,8 @@ class ThermionViewerFFI extends ThermionViewer {
       bool replaceActive = true,
       double crossfade = 0.0,
       double startOffset = 0.0}) async {
-    play_animation(
-        _sceneManager!, entity, index, loop, reverse, replaceActive, crossfade, startOffset);
+    play_animation(_sceneManager!, entity, index, loop, reverse, replaceActive,
+        crossfade, startOffset);
   }
 
   ///

thermion_dart/lib/thermion_dart/thermion_viewer_stub.dart

@@ -1,4 +1,5 @@
 import 'dart:math';
+import 'dart:typed_data';
 
 import 'package:thermion_dart/thermion_dart/scene.dart';
 import 'package:thermion_dart/thermion_dart/thermion_viewer.dart';
@@ -750,4 +751,10 @@ class ThermionViewerStub extends ThermionViewer {
     // TODO: implement setSoftShadowOptions
     throw UnimplementedError();
   }
+
+  @override
+  Future<Uint8List> capture() {
+    // TODO: implement capture
+    throw UnimplementedError();
+  }
 }

thermion_dart/native/include/FilamentViewer.hpp

@@ -150,6 +150,7 @@ namespace thermion_filament
 
         void setRecording(bool recording);
         void setRecordingOutputDirectory(const char *path);
+        void capture(uint8_t *out, void (*onComplete)());
 
         void setAntiAliasing(bool msaaEnabled, bool fxaaEnabled, bool taaEnabled);
         void setDepthOfField();

thermion_dart/native/include/ThermionDartApi.h

@@ -107,6 +107,10 @@ extern "C"
 		void *pixelBuffer,
 		void (*callback)(void *buf, size_t size, void *data),
 		void *data);
+	EMSCRIPTEN_KEEPALIVE void capture(
+		const void *const viewer,
+		uint8_t *pixelBuffer,
+		void (*callback)(void));
 	EMSCRIPTEN_KEEPALIVE void create_swap_chain(const void *const viewer, const void *const window, uint32_t width, uint32_t height);
 	EMSCRIPTEN_KEEPALIVE void destroy_swap_chain(const void *const viewer);
 	EMSCRIPTEN_KEEPALIVE void set_frame_interval(const void *const viewer, float interval);

thermion_dart/native/include/ThermionDartFFIApi.h

@@ -30,6 +30,7 @@ extern "C"
     EMSCRIPTEN_KEEPALIVE void create_render_target_ffi(void *const viewer, intptr_t nativeTextureId, uint32_t width, uint32_t height, void (*onComplete)());
     EMSCRIPTEN_KEEPALIVE void destroy_filament_viewer_ffi(void *const viewer);
     EMSCRIPTEN_KEEPALIVE void render_ffi(void *const viewer);
+    EMSCRIPTEN_KEEPALIVE void capture_ffi(void *const viewer, uint8_t* out, void (*onComplete)());
     EMSCRIPTEN_KEEPALIVE FilamentRenderCallback make_render_callback_fn_pointer(FilamentRenderCallback);
     EMSCRIPTEN_KEEPALIVE void set_rendering_ffi(void *const viewer, bool rendering, void(*onComplete)());
     EMSCRIPTEN_KEEPALIVE void set_frame_interval_ffi(void *const viewer, float frameInterval);

thermion_dart/native/src/FilamentViewer.cpp

@@ -1186,6 +1186,49 @@ namespace thermion_filament
     #endif
   }
 
+  void FilamentViewer::capture(uint8_t *out, void (*onComplete)()) {
+      
+      Viewport const &vp = _view->getViewport();
+      size_t pixelBufferSize = vp.width * vp.height * 4;
+      auto *pixelBuffer = new uint8_t[pixelBufferSize];
+      auto callback = [](void *buf, size_t size, void *data)
+      {
+
+        auto frameCallbackData = (std::vector<void*>*)data;
+        uint8_t *out = (uint8_t *)(frameCallbackData->at(0));
+        void* callbackPtr = frameCallbackData->at(1);
+
+        void (*callback)(void) = (void (*)(void))callbackPtr;
+        memcpy(out, buf, size);
+        delete frameCallbackData;
+        callback();
+      };
+
+      auto userData = new std::vector<void*> { out, (void*)onComplete } ;
+
+      auto pbd = Texture::PixelBufferDescriptor(
+          pixelBuffer, pixelBufferSize,
+          Texture::Format::RGBA,
+          Texture::Type::UBYTE, nullptr, callback, userData);
+      _renderer->beginFrame(_swapChain, 0);
+      
+      _renderer->render(_view);
+
+      if(_rt) {
+        _renderer->readPixels(_rt, 0, 0, vp.width, vp.height, std::move(pbd));
+      } else { 
+        _renderer->readPixels(0, 0, vp.width, vp.height, std::move(pbd));
+      }
+      _renderer->endFrame();
+
+      #ifdef __EMSCRIPTEN__
+        _engine->execute();
+        emscripten_webgl_commit_frame();
+      #endif
+    }
+
+
+
   void FilamentViewer::savePng(void *buf, size_t size, int frameNumber)
   {
     // std::lock_guard lock(_recordingMutex);

thermion_dart/native/src/ThermionDartApi.cpp

@@ -329,6 +329,13 @@ extern "C"
         ((FilamentViewer *)viewer)->render(frameTimeInNanos, pixelBuffer, callback, data);
     }
 
+    EMSCRIPTEN_KEEPALIVE void capture(
+		const void *const viewer,
+		uint8_t *pixelBuffer,
+		void (*callback)(void)) {
+            ((FilamentViewer *)viewer)->capture(pixelBuffer, callback);
+        };
+
     EMSCRIPTEN_KEEPALIVE void set_frame_interval(
         const void *const viewer,
         float frameInterval)

thermion_dart/native/src/ThermionDartFFIApi.cpp

@@ -373,6 +373,12 @@ extern "C"
     auto fut = _rl->add_task(lambda);
   }
 
+  EMSCRIPTEN_KEEPALIVE void capture_ffi(void *const viewer, uint8_t* pixelBuffer, void (*onComplete)()) {
+    std::packaged_task<void()> lambda([=]() mutable
+                                      { capture(viewer, pixelBuffer, onComplete); });
+    auto fut = _rl->add_task(lambda);
+  }
+
   EMSCRIPTEN_KEEPALIVE void
   set_background_color_ffi(void *const viewer, const float r, const float g,
                            const float b, const float a)