opengl: restructure code for computing format support.

src/modules/graphics/opengl/Graphics.cpp

@@ -112,7 +112,7 @@ Graphics::Graphics()
 	, bufferMapMemory(nullptr)
 	, bufferMapMemorySize(2 * 1024 * 1024)
 	, defaultBuffers()
-	, supportedFormats()
+	, pixelFormatUsage()
 {
 	gl = OpenGL();
 
@@ -1670,6 +1670,13 @@ void Graphics::initCapabilities()
 
 	for (int i = 0; i < TEXTURE_MAX_ENUM; i++)
 		capabilities.textureTypes[i] = gl.isTextureTypeSupported((TextureType) i);
+
+	for (int i = 0; i < PIXELFORMAT_MAX_ENUM; i++)
+	{
+		auto format = (PixelFormat) i;
+		pixelFormatUsage[i][0] = computePixelFormatUsage(format, false);
+		pixelFormatUsage[i][1] = computePixelFormatUsage(format, true);
+	}
 }
 
 PixelFormat Graphics::getSizedFormat(PixelFormat format, bool rendertarget, bool readable) const
@@ -1697,56 +1704,27 @@ PixelFormat Graphics::getSizedFormat(PixelFormat format, bool rendertarget, bool
 	}
 }
 
-bool Graphics::isPixelFormatSupported(PixelFormat format, uint32 usage, bool sRGB)
+uint32 Graphics::computePixelFormatUsage(PixelFormat format, bool readable)
 {
-	if (sRGB)
-	{
-		format = getSRGBPixelFormat(format);
-		sRGB = false;
-	}
+	uint32 usage = OpenGL::getPixelFormatUsageFlags(format);
 
-	bool rendertarget = (usage & PIXELFORMATUSAGEFLAGS_RENDERTARGET) != 0;
-	bool readable = (usage & PIXELFORMATUSAGEFLAGS_SAMPLE) != 0;
-	bool computewrite = (usage & PIXELFORMATUSAGEFLAGS_COMPUTEWRITE) != 0;
-
-	format = getSizedFormat(format, rendertarget, readable);
-
-	OptionalBool &supported = supportedFormats[format][rendertarget ? 1 : 0][readable ? 1 : 0][computewrite ? 1 : 0][sRGB ? 1 : 0];
-
-	if (supported.hasValue)
-		return supported.value;
-
-	uint32 supportedflags = OpenGL::getPixelFormatUsageFlags(format);
-
-	if ((usage & supportedflags) != usage)
-	{
-		supported.set(false);
-		return supported.value;
-	}
-
-	if (!rendertarget)
-	{
-		supported.set(true);
-		return supported.value;
-	}
+	if (readable && (usage & PIXELFORMATUSAGEFLAGS_SAMPLE) == 0)
+		return 0;
 
 	// Even though we might have the necessary OpenGL version or extension,
 	// drivers are still allowed to throw FRAMEBUFFER_UNSUPPORTED when attaching
 	// a texture to a FBO whose format the driver doesn't like. So we should
 	// test with an actual FBO.
-	GLuint texture = 0;
-	GLuint renderbuffer = 0;
-
 	// Avoid the test for depth/stencil formats - not every GL version
 	// guarantees support for depth/stencil-only render targets (which we would
 	// need for the test below to work), and we already do some finagling in
 	// convertPixelFormat to try to use the best-supported internal
 	// depth/stencil format for a particular driver.
-	if (isPixelFormatDepthStencil(format))
+	if ((usage & PIXELFORMATUSAGEFLAGS_RENDERTARGET) != 0 && !isPixelFormatDepthStencil(format))
 	{
-		supported.set(true);
-		return true;
-	}
+		GLuint texture = 0;
+		GLuint renderbuffer = 0;
+		bool sRGB = isPixelFormatSRGB(format);
 
 		OpenGL::TextureFormat fmt = OpenGL::convertPixelFormat(format, !readable, sRGB);
 
@@ -1790,7 +1768,8 @@ bool Graphics::isPixelFormatSupported(PixelFormat format, uint32 usage, bool sRG
 				glFramebufferRenderbuffer(GL_FRAMEBUFFER, attachment, GL_RENDERBUFFER, renderbuffer);
 		}
 
-	supported.set(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE);
+		if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+			usage &= ~PIXELFORMATUSAGEFLAGS_RENDERTARGET;
 
 		gl.bindFramebuffer(OpenGL::FRAMEBUFFER_ALL, current_fbo);
 		gl.deleteFramebuffer(fbo);
@@ -1800,8 +1779,22 @@ bool Graphics::isPixelFormatSupported(PixelFormat format, uint32 usage, bool sRG
 
 		if (renderbuffer != 0)
 			glDeleteRenderbuffers(1, &renderbuffer);
+	}
 
-	return supported.value;
+	return usage;
+}
+
+bool Graphics::isPixelFormatSupported(PixelFormat format, uint32 usage, bool sRGB)
+{
+	if (sRGB)
+		format = getSRGBPixelFormat(format);
+
+	bool rendertarget = (usage & PIXELFORMATUSAGEFLAGS_RENDERTARGET) != 0;
+	bool readable = (usage & PIXELFORMATUSAGEFLAGS_SAMPLE) != 0;
+
+	format = getSizedFormat(format, rendertarget, readable);
+
+	return (usage & pixelFormatUsage[format][readable ? 1 : 0]) == usage;
 }
 
 } // opengl

src/modules/graphics/opengl/Graphics.h

@@ -155,6 +155,8 @@ private:
 
 	void setDebug(bool enable);
 
+	uint32 computePixelFormatUsage(PixelFormat format, bool readable);
+
 	std::unordered_map<RenderTargets, GLuint, CachedFBOHasher> framebufferObjects;
 	bool windowHasStencil;
 	GLuint mainVAO;
@@ -170,8 +172,8 @@ private:
 	// Only needed for buffer types that can be bound to shaders.
 	StrongRef<love::graphics::Buffer> defaultBuffers[BUFFERUSAGE_MAX_ENUM];
 
-	// [rendertarget][readable][computewrite][srgb]
-	OptionalBool supportedFormats[PIXELFORMAT_MAX_ENUM][2][2][2][2];
+	// [non-readable, readable]
+	uint32 pixelFormatUsage[PIXELFORMAT_MAX_ENUM][2];
 
 }; // Graphics