I use glBlendColor (0,0,0,1) to set the alpha value to 1. Then i do a glBlendFunc (GL_CONSTANT_ALPHA, GL_ONE_MINUS_CONSTANT_ALPHA).
However the glBlendColor does not really set the alpha value. When i read it out after the call to glBlendColor, it is still 0. Therefore I see no image on the screen when I do a glDrawPixels(..) (because the src var of glBlendFunc = 0 and the dst var = 1, so the image to draw is complete transparent).
Does anyone know this problem, or has a solution for it ?