PDA

View Full Version : Simultaneous Lighting and Blending impossible?



Nick Nougat
11-30-2002, 01:38 PM
Hi!

It seems, when unsing blending and lighting, I can only get one of them to work at a time... That is, if I enable lighting, blending does not work.
Is this an internal restriction or did I just miss an important state configuration part?

Thanks
Nick

Bob
11-30-2002, 05:02 PM
They are two separated operations and work independently. Your problem is probably that you use the alpha channel of the primary color (glColor for example) to control transparency. When lighting is enabled, the primary color is calculated using the lighting equations, and the value you pass is not used. When lighting is enabled, you change the material of the object using glMaterial.

Nick Nougat
11-30-2002, 05:15 PM
Thanks! I see now!
Anyway I think it's strange, that when the alpha value of the 'glColor' color got 0 the object was not rendered although any non-zero alpha values have no effect on transparency.
I guess it must be some form of optimization, that avoids drawing when the primary alpha is zero or something...
What do you think?

Nick