GL_EXT_blend_func_extended
https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_blend_func_extended.txt
GL_EXT_blend_func_extended

	GL_SRC_ALPHA_SATURATE_EXT 0x0308
	GL_SRC1_ALPHA_EXT 0x8589
	GL_SRC1_COLOR_EXT 0x88F9
	GL_ONE_MINUS_SRC1_COLOR_EXT 0x88FA
	GL_ONE_MINUS_SRC1_ALPHA_EXT 0x88FB
	GL_MAX_DUAL_SOURCE_DRAW_BUFFERS_EXT 0x88FC
	GL_LOCATION_INDEX_EXT 0x930F
	void glBindFragDataLocationIndexedEXT (GLuint program, GLuint colorNumber, GLuint index, const GLchar * name)
	GLint glGetFragDataIndexEXT (GLuint program, const GLchar * name)
	GLint glGetProgramResourceLocationIndexEXT (GLuint program, GLenum programInterface, const GLchar* name)