GL_EXT_texture_perturb_normal
https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_perturb_normal.txt
GL_EXT_texture_perturb_normal

	GL_PERTURB_EXT 0x85AE
	GL_TEXTURE_NORMAL_EXT 0x85AF
	void glTextureNormalEXT (GLenum mode)