GL_ARB_shadow
https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_shadow.txt
GL_ARB_shadow

	GL_TEXTURE_COMPARE_MODE_ARB 0x884C
	GL_TEXTURE_COMPARE_FUNC_ARB 0x884D
	GL_COMPARE_R_TO_TEXTURE_ARB 0x884E