First of all, what is pixel shader? I''ve heard that term a few times, and I didn''t find much info about it, and I can''t really figure out what it is from its name... Second, does anyone here know how to do bump mapping on an implicit surface? Example: I have a scalar function f(x,y,z), and I want to use that function to generate heights on the surface of a sphere (raytraced with the implicit equation of a sphere). I can''t figure out a simple way to do it. I want to generate scalar heights, not vector displacements. ANy help?

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Besides, you should have asked this in the Graphics programming forum.

Cédric

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Original post by vanillacoke Second, does anyone here know how to do bump mapping on an implicit surface? Example: I have a scalar function f(x,y,z), and I want to use that function to generate heights on the surface of a sphere (raytraced with the implicit equation of a sphere). I can''t figure out a simple way to do it. I want to generate scalar heights , not vector displacements. ANy help?

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One way would be to use finite differencing to calculate the normal at a point. Basically take the heights at adjacent points, and find the normal vector from that.

cedric: sorry, I guess I didn''t realize that there is a graphics forum.

skjeld: is finite differencing something that allows you to analyze an implicit surface? I''ll go try to read about it.

finite differencing is a way of computing a derivative. Here you can use it to create the normal vector.

To find the derivative of what? I already know how to take the derivative of a function. To find the normal vector to an implicit surface, don''t you just use the gradient?

It''s the partial derivative with respect to x,y,z(the direction you do differencing in)

and the gradient is the vector of partial derivatives...

A pixel shader is a program(called a shader), which is run per pixel. For shorter shaders, this is typical, a simple mathematical equation, for example a lighting equation. Check out cgshaders.org. There are quite a few graphics apis that use pixels shaders. Opengl and DirectX are the most famous that do it in real time.