[Native] OpenGL FrameBuffer Multiple Render Targets support - possible gl.drawBuffers() not supported?

singmajesty · August 17, 2017, 4:30pm

After our conversation (the first time), I went back and looked into supported GLES3 APIs on native. Good news! I believe it is working, currently implemented for Linux and Emscripten, but I hope to enable it in a way that does not require newer GL libraries on Windows or Mac:

For example, here’s drawBuffers on the C++ side:

github.com

openfl/lime/blob/develop/project/src/graphics/opengl/OpenGLBindings.cpp#L774-L789


	void lime_gl_draw_buffers (value buffers) {
		
		#ifdef LIME_GLES3_API
		GLsizei size = val_array_size (buffers);
		GLenum *_buffers = (GLenum*)alloca (size * sizeof(GLenum));
		
		for (int i = 0; i < size; i++) {
			
			_buffers[i] = val_int (val_array_i (buffers, i));
			
		}
		
		glDrawBuffers (size, _buffers);
		#endif
		
	}

I disabled LIME_GLES3_API on Windows and Mac, because (depending on the version of the compiler and system GL library) it would complain about some missing symbols when linking. This is solvable, but just requires a bit more work, but on your machine, it should be possible to add LIME_GLES_API under the “project/src/graphics/opengl/OpenGL.h” file (based on the platform) then comment out a couple calls it complains about if your system doesn’t have them

Anyway, just let me know if you want to try this out or how I can help