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{ RCSid $Id$ }
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{
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Unit cylinder functions (centered on Z-axis)
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for testing
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}
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posAngle(a):if(a,a,a+2*PI);
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Cx = posAngle(atan2(Py,Px));
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Cy = Pz;
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Rx(n) = n/(2*PI) * Cx;
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Ry(n) = n/(2*PI) * Cy;
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Sx(n) = .5*(Rx(n) - Ry(n));
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Sy(n) = .5*(Rx(n) + Ry(n));
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{ Checkerboard pattern }
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Check(n) = xor(frac(Rx(n))-.5, frac(Ry(n))-.5);
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{ Pyramid texture }
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Pyramid_dxy(n) = if(frac(Rx(2*n))-.5, .2, -.2);
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Pyramid_dx(n) = -Py*Pyramid_dxy(n);
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Pyramid_dy(n) = Px*Pyramid_dxy(n);
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Pyramid_dz(n) = if(frac(Ry(2*n))-.5, .2, -.2);
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