GL_SGIX_texture_mipmap_anisotropic
http://www.opengl.org/registry/specs/SGIX/texture_mipmap_anisotropic.txt
GL_SGIX_texture_mipmap_anisotropic

	GL_TEXTURE_MIPMAP_ANISOTROPY_SGIX 0x832E
	GL_MAX_MIPMAP_ANISOTROPY_SGIX 0x832F