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76 lines
1.6 KiB
JavaScript
76 lines
1.6 KiB
JavaScript
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/*
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DynAPI Distribution
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Bezier Class
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Bezier Algorithm Reference: http://astronomy.swin.edu.au/~pbourke/curves/bezier/
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The DynAPI Distribution is distributed under the terms of the GNU LGPL license.
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requires: dynapi.fx.Thread
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*/
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function Bezier(cp, n) {
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var l = cp.length;
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var p = [];
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for (var i=0; i<n; i++) p = p.concat(Bezier._plot(cp,i/n));
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return p.concat([cp[l-2],cp[l-1]]);
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}
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Bezier._plot = function (cp, mu) {
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var n = (cp.length/2)-1;
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var k,kn,nn,nkn;
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var blend;
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var b = [0,0];
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var muk = 1;
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var munk = Math.pow(1-mu, n);
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for (k=0;k<=n;k++) {
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nn = n;
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kn = k;
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nkn = n - k;
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blend = muk * munk;
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muk *= mu;
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munk /= (1-mu);
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while (nn >= 1) {
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blend *= nn;
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nn--;
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if (kn > 1) {
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blend /= kn;
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kn--;
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}
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if (nkn > 1) {
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blend /= nkn;
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nkn--;
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}
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}
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b[0] += cp[k*2] * blend;
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b[1] += cp[k*2+1] * blend;
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}
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b[0] = Math.round(b[0]);
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b[1] = Math.round(b[1]);
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return b;
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}
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/*function Bezier3(cp,mu) {
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var x1=cp[0],y1=cp[1],x2=cp[2],y2=cp[3],x3=cp[4],y3=cp[5];
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var mu2 = mu * mu;
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var mum1 = 1 - mu;
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var mum12 = mum1 * mum1;
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var x = Math.round(x1 * mum12 + 2 * x2 * mum1 * mu + x3 * mu2);
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var y = Math.round(y1 * mum12 + 2 * y2 * mum1 * mu + y3 * mu2);
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return [x,y];
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}
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function Bezier4(cp,mu) {
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var x1=cp[0],y1=cp[1],x2=cp[2],y2=cp[3],x3=cp[4],y3=cp[5],x4=cp[6],y4=cp[7];
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var mum1 = 1 - mu;
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var mum13 = mum1 * mum1 * mum1;
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var mu3 = mu * mu * mu;
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var x = Math.round(mum13*x1 + 3*mu*mum1*mum1*x2 + 3*mu*mu*mum1*x3 + mu3*x4);
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var y = Math.round(mum13*y1 + 3*mu*mum1*mum1*y2 + 3*mu*mu*mum1*y3 + mu3*y4);
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return [x,y];
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}*/
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