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{ RCSid $Id$ } |
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{ |
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Uniform Rational Patch |
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|
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02Mar90 |
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|
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Define Px(i,j), Py(i,j), Pz(i,j) and W(i,j), nrows, ncols |
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} |
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{ default basis functions } |
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br(a,b,c,d,s) = b3(a,b,c,d,s); |
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bc(a,b,c,d,t) = b3(a,b,c,d,t); |
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b3(a,b,c,d,p) = bezier(a,b,c,d,p); |
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{ default patch interpolation } |
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rint = interpolate; |
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cint = interpolate; |
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interpolate = 1; |
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|
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x(s,t) = patch(s,t,Px); |
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y(s,t) = patch(s,t,Py); |
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z(s,t) = patch(s,t,Pz); |
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|
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patch(s,t,p) = bc(P2(s,c0(t)+1,p), P2(s,c0(t)+2,p), |
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P2(s,c0(t)+3,p), P2(s,c0(t)+4,p), cf(t)) / |
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bc(W2(s,c0(t)+1), W2(s,c0(t)+2), |
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W2(s,c0(t)+3), W2(s,c0(t)+4), cf(t)) ; |
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|
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P2(s,j,p) = br(W(1+r0(s),j)*p(1+r0(s),j), W(2+r0(s),j)*p(2+r0(s),j), |
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W(3+r0(s),j)*p(3+r0(s),j), W(4+r0(s),j)*p(4+r0(s),j), rf(s)) ; |
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|
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W2(s,j) = br(W(1+r0(s),j), W(2+r0(s),j), W(3+r0(s),j), W(4+r0(s),j), rf(s)) ; |
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|
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r0(s) = rmult*floor(clamp(s)*npr); |
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rf(s) = s*npr - floor(clamp(s)*npr); |
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c0(t) = cmult*floor(clamp(t)*npc); |
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cf(t) = t*npc - floor(clamp(t)*npc); |
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|
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rmult = if(rint, 4, 1); |
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cmult = if(cint, 4, 1); |
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npr = if(rint, nrows/4, nrows-3); |
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npc = if(cint, ncols/4, ncols-3); |
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|
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clamp(p) = if(p, if(1-p, p, .9999999), .0000001); |
