hi i m trying to write my own illumination model using open GL. I want to know how do i control the intensity of each pixel. How do i use the material properties to illuminate the objects.

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OpenGL comes with a default implementation for lighting, are you trying to learn how to use it, or are you writing your own because it is unsatisfactory? (for example if you want more than 8 dynamic lights)

If you are just trying to learn openGL''s light system theres lots of good tutorials, try searching for NeHeGL.

If you are trying to write your own lighting system that bypasses the openGL pipeline then you''ll have to ask someone with bigger brains than me Its actually done pretty often (by pros) and the whole point of openGL 1.4 was to allow programmable vertex pipelines to do exactly that sort of thing.