GL_NV_texture_env_combine4
https://www.khronos.org/registry/OpenGL/extensions/NV/NV_texture_env_combine4.txt
GL_NV_texture_env_combine4

	GL_COMBINE4_NV 0x8503
	GL_SOURCE3_RGB_NV 0x8583
	GL_SOURCE3_ALPHA_NV 0x858B
	GL_OPERAND3_RGB_NV 0x8593
	GL_OPERAND3_ALPHA_NV 0x859B