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TheSeb

[GLSL]is it possible of making parallax bump mapping without multipass ?

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Hi, I don't manage to find how make this in a single pass, do you know how ? Otherwise where can i find documentation about multipass rendering and how rendre to a texture ?

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Quote:
Original post by TheSeb
sorry, "the current shader" ?

He means your basic bump mapping shader. Parallax mapping (essentially a texture distortion effect) is an extension to standard DOT3 based bump mapping, which will only modulate the pixel colour on its own.

You start by writing a standard DOT3 pixelshader, and add a few lines to get the parallax effect on the texture UVs.

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it is from the documentation above. Somebody can explain me what is the bias here ? :


"To compute a texture coordinate offset at a point P, the eye vector must first be normalized
to produce a normalized eye vector V. The height h at the original texture coordinate To is
read from the height map. The height is scaled by a scale factor s and biased by a bias b in
order to map the height from the range {0.0, 1.0} to a range that better represents the
physical properties of the surface being simulated. For example, a brick wall texture might
cover a 2x2 meter area. Also imagine the surface of the bricks and the recessed grout give
the surface a thickness of 0.02m. The correct scale factor for this material would be 0.02 /
2 = 0.01. Coupling this with a bias of 0.0 would then remap the height field to a range of
{0.0, 0.01}. Using a bias of ­0.01
would remap the range to {­0.99,
0.0}. The average of
these two extremes is probably best for most textures.
b = s ∙ ­0.5"

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In Greek mythology, Bias was a brother of Melampus who received one third of Argos (see Melampus for more information). Bias married Pero. He was the father of Talaus with Pero. :)

But really bias = offset, I think :)

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