1GL_SGIX_async_pixel 2http://www.opengl.org/registry/specs/SGIX/async_pixel.txt 3GL_SGIX_async_pixel 4 5 GL_ASYNC_TEX_IMAGE_SGIX 0x835C 6 GL_ASYNC_DRAW_PIXELS_SGIX 0x835D 7 GL_ASYNC_READ_PIXELS_SGIX 0x835E 8 GL_MAX_ASYNC_TEX_IMAGE_SGIX 0x835F 9 GL_MAX_ASYNC_DRAW_PIXELS_SGIX 0x8360 10 GL_MAX_ASYNC_READ_PIXELS_SGIX 0x8361 11