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{ |
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Carpet function. |
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|
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Scale pattern to tuft size. |
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|
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A1 - tuft red color |
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A2 - tuft green color |
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A3 - tuft blue color |
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A4 - degree of variation |
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} |
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{ carpet tuft position } |
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{ Varies from [(1-A4),1] based on Perlin 3D noise function, a random wave |
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function over 3D space, with scalar value everywhere between about -1 and 1. |
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Sense of this is 0 means bottom of tuft and 1 means top (carpet surface). } |
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carpt = 1 - A4*(.5+.5*noise3(Px,Py,Pz)); |
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{ exponent for carpet color } |
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{ Takes [(1-A4),1] range and maps it to [1,(1+4*A4)] for # interreflections } |
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carpe = 1 + 4*(1-carpt); |
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{ coefficient (with fuzzies) } |
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{ Takes square of carpt as general shading coefficient (self-shadowing) |
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and multiplies by some fractal noise hovering around 1 with a base frequency |
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10 times the tuft frequency (fuzzies). The noneg() function guarantees |
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positive results for outlying values of the noise functions. } |
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coef = noneg( carpt*carpt * (1 + .25*A4*fnoise3(Px*10,Py*10,Pz*10)) ); |
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{ carpet color } |
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{ Final color is shading coefficient times carpet color raised to the power |
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of the number of interreflections, which causes both darkening and |
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deepening of color in between tufts. } |
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carpr = coef * A1^carpe; |
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carpg = coef * A2^carpe; |
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carpb = coef * A3^carpe; |
