Add: [OpenGL] Support for a separate animation buffer that stores the palette values of the screen in addition to the colour buffer.

src/video/win32_v.h

@@ -128,7 +128,7 @@ public:
 /** The OpenGL video driver for windows. */
 class VideoDriver_Win32OpenGL : public VideoDriver_Win32Base {
 public:
-	VideoDriver_Win32OpenGL() : dc(nullptr), gl_rc(nullptr) {}
+	VideoDriver_Win32OpenGL() : dc(nullptr), gl_rc(nullptr), anim_buffer(nullptr) {}
 
 	const char *Start(const StringList &param) override;
 
@@ -144,12 +144,16 @@ public:
 
 	void ClearSystemSprites() override;
 
+	bool HasAnimBuffer() override { return true; }
+	uint8 *GetAnimBuffer() override { return this->anim_buffer; }
+
 	const char *GetName() const override { return "win32-opengl"; }
 
 protected:
-	HDC   dc;          ///< Window device context.
-	HGLRC gl_rc;       ///< OpenGL context.
-	bool  vsync;       ///< Enable VSync?
+	HDC    dc;          ///< Window device context.
+	HGLRC  gl_rc;       ///< OpenGL context.
+	bool   vsync;       ///< Enable VSync?
+	uint8 *anim_buffer; ///< Animation buffer from OpenGL back-end.
 
 	uint8 GetFullscreenBpp() override { return 32; } // OpenGL is always 32 bpp.