Other Blend Functions

General blending formula is:

R = SourceFactor * R_s + DestinationFactor * R_d
G = SourceFactor * G_s + DestinationFactor * G_d
B = SourceFactor * B_s + DestinationFactor * B_d

(R_s, G_s, B_s) is the source color (object being drawn)
(R_d, G_d, B_d) is the destination color (color already in the framebuffer)

SourceFactor and DestinationFactor are defined by glBlendFunc()