GL_ARB_draw_buffers
http://www.opengl.org/registry/specs/ARB/draw_buffers.txt
GL_ARB_draw_buffers
GL_MAX_DRAW_BUFFERS_ARB 0x8824
GL_DRAW_BUFFER0_ARB 0x8825
GL_DRAW_BUFFER1_ARB 0x8826
GL_DRAW_BUFFER2_ARB 0x8827
GL_DRAW_BUFFER3_ARB 0x8828
GL_DRAW_BUFFER4_ARB 0x8829
GL_DRAW_BUFFER5_ARB 0x882A
GL_DRAW_BUFFER6_ARB 0x882B
GL_DRAW_BUFFER7_ARB 0x882C
GL_DRAW_BUFFER8_ARB 0x882D
GL_DRAW_BUFFER9_ARB 0x882E
GL_DRAW_BUFFER10_ARB 0x882F
GL_DRAW_BUFFER11_ARB 0x8830
GL_DRAW_BUFFER12_ARB 0x8831
GL_DRAW_BUFFER13_ARB 0x8832
GL_DRAW_BUFFER14_ARB 0x8833
GL_DRAW_BUFFER15_ARB 0x8834
void glDrawBuffersARB (GLsizei n, const GLenum* bufs)