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# OpenGL [OPENGL] How do Light and materials interact?

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I''ve been reading the Redbook and something that i havent picked up on is the interaction between light and materials. For example just say I have a light with specular of X, how does that relate to a surface with a material specular of Y. Actually I don''t even ''get'' how a light can be specular... Is the specular component of a light source the portion that ''lights up'' the specular portion of the material, eg if a light with no specular component shines on a shiny glass the glass remain dull? Many thanks for any direction Chris

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check the ''specular term'' section section of the red book (pg208 2edit)is very well explained there how the specular adds to the colour.also computer graphics principles and practice have quite a lot of info on it as well

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Thats again Zed. I took your advice and... as a result reread almost the entire chapter ... From what i understand the surfaces material properties sort of specify the maximum properties that the material is capably of being lit to.

The light components then individually add to the ''black'' components on the surface material to produce the relative lighting levels for each component.

Did I get it right?

Chris

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>>The light components then individually add to the ''black'' components on the surface material to produce the relative lighting levels for each component<<

they add to the current colour

eg for diffuse lighting other forms are simular
how much diffuse light point recieves * colour of diffuse light * colour of diffuse material1   (totally lit)                    *    red                       * 1.0 (white diffuse material) = bright red1   (totally lit)                    *    red                       * 0.5 (grey diffuse material) = crimson1   (totally lit)                    *    red                       * 0.0 (white diffuse material) = black

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