Hello, I changed my previous question to this: Given: -OpenGL Standard Lighting -1 enabled point light with ambient=diffuse, no specular -one object -no global ambient lighting 1. Render the object as usual 2. Render in 2 passes 1st: light's diffuse set to zero 2nd: enable blending (GL_FUNC_ADD, GL_ONE, GL_ONE) restore light's diffuse color set light's ambient color to zero Shouldn't the output be the same? In Method 1 diffuse and ambient are added per vertex. Method 2 does it in the frame buffer. Why is the output of Method 2 much brighter than method 1? Thanks a lot. Markus [Edited by - muhkuh on December 2, 2005 6:00:32 AM]

Are you texturing this object?