GL_SGIX_texture_scale_bias
http://www.opengl.org/registry/specs/SGIX/texture_scale_bias.txt
	GL_POST_TEXTURE_FILTER_BIAS_SGIX 0x8179
	GL_POST_TEXTURE_FILTER_SCALE_SGIX 0x817A
	GL_POST_TEXTURE_FILTER_BIAS_RANGE_SGIX 0x817B
	GL_POST_TEXTURE_FILTER_SCALE_RANGE_SGIX 0x817C
