initial work on custom Platform to wrap EGL D3D surface

windows/PlatformANGLE.h

@@ -0,0 +1,99 @@
+#ifndef _POLYVOX_FILAMENT_PLATFORM_ANGLE_H
+#define _POLYVOX_FILAMENT_PLATFORM_ANGLE_H
+
+#include <d3d.h>
+#include <d3d11.h>
+
+#include "backend/platforms/OpenGLPlatform.h"
+#include "backend/Platform.h"
+
+namespace filament::backend {
+
+/**
+ * A concrete implementation of OpenGLPlatform that supports EGL with a headless swapchain and external D3D texture support.
+ */
+class PlatformANGLE : public OpenGLPlatform {
+public:
+    PlatformANGLE(HANDLE d3dTextureHandle, uint32_t width, uint32_t height) noexcept;
+
+    Driver* createDriver(void* sharedContext,
+            const Platform::DriverConfig& driverConfig) noexcept override;
+
+    Platform::SwapChain* createSwapChain(void* nativewindow, uint64_t flags) noexcept override;
+
+    Platform::SwapChain* createSwapChain(uint32_t width, uint32_t height, uint64_t flags)  noexcept override;
+
+private:
+    /**
+     * This returns zero. This method can be overridden to return something more useful.
+     * @return zero
+     */
+    int getOSVersion() const noexcept override;
+
+    // --------------------------------------------------------------------------------------------
+    // OpenGLPlatform Interface
+
+    void terminate() noexcept override;
+
+    bool isSRGBSwapChainSupported() const noexcept override;
+    void destroySwapChain(SwapChain* swapChain) noexcept override;
+    void makeCurrent(SwapChain* drawSwapChain, SwapChain* readSwapChain) noexcept override;
+    void commit(SwapChain* swapChain) noexcept override;
+
+    bool canCreateFence() noexcept override;
+    Fence* createFence() noexcept override;
+    void destroyFence(Fence* fence) noexcept override;
+    FenceStatus waitFence(Fence* fence, uint64_t timeout) noexcept override;
+
+    OpenGLPlatform::ExternalTexture* createExternalImageTexture() noexcept override;
+    void destroyExternalImage(ExternalTexture* texture) noexcept override;
+    bool setExternalImage(void* externalImage, ExternalTexture* texture) noexcept override;
+
+    /**
+     * Logs glGetError() to slog.e
+     * @param name a string giving some context on the error. Typically __func__.
+     */
+    static void logEglError(const char* name) noexcept;
+
+    /**
+     * Calls glGetError() to clear the current error flags. logs a warning to log.w if
+     * an error was pending.
+     */
+    static void clearGlError() noexcept;
+
+    /**
+     * Always use this instead of eglMakeCurrent().
+     */
+    EGLBoolean makeCurrent(EGLSurface drawSurface, EGLSurface readSurface) noexcept;
+
+    // TODO: this should probably use getters instead.
+    EGLDisplay mEGLDisplay = EGL_NO_DISPLAY;
+    EGLContext mEGLContext = EGL_NO_CONTEXT;
+    EGLSurface mCurrentDrawSurface = EGL_NO_SURFACE;
+    EGLSurface mCurrentReadSurface = EGL_NO_SURFACE;
+    EGLSurface mEGLDummySurface = EGL_NO_SURFACE;
+    EGLConfig mEGLConfig = EGL_NO_CONFIG_KHR;
+    HANDLE mD3DTextureHandle = nullptr;
+    uint32_t mWidth = 0;
+    uint32_t mHeight = 0;
+
+    // supported extensions detected at runtime
+    struct {
+        struct {
+            bool OES_EGL_image_external_essl3 = false;
+        } gl;
+        struct {
+            bool KHR_no_config_context = false;
+            bool KHR_gl_colorspace = false;
+        } egl;
+    } ext;
+
+private:
+    void initializeGlExtensions() noexcept;
+    EGLConfig findSwapChainConfig(uint64_t flags) const;
+
+};
+
+} // namespace filament
+
+#endif // _POLYVOX_FILAMENT_PLATFORM_ANGLE_H