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import three;
size(10cm);
currentprojection=perspective(50,80,50);
// Nonrational surface:
// udegree=3, vdegree=3, nu=5, nv=6;
real[] uknot={0,0,0,0,0.5,1,1,1,1};
real[] vknot={0,0,0,0,0.4,0.6,1,1,1,1};
triple[][] P={{
(-31.2061,12.001,6.45082),
(-31.3952,14.7353,6.53707),
(-31.5909,21.277,6.70051),
(-31.4284,25.4933,6.76745),
(-31.5413,30.3485,6.68777),
(-31.4896,32.2839,6.58385),
},{
(-28.279,12.001,7.89625),
(-28.4187,14.7353,8.00954),
(-28.5633,21.277,8.22422),
(-28.4433,25.4933,8.31214),
(-28.5266,30.3485,8.20749),
(-28.4885,32.2839,8.07099),
},{
(-20,12.001,10.0379),
(-20,14.7353,10.2001),
(-20,21.277,10.5076),
(-20,25.4933,10.6335),
(-20,30.3485,10.4836),
(-20,32.2839,10.2881),
},{
(-11.721,12.001,7.84024),
(-11.5813,14.7353,7.95269),
(-11.4367,21.277,8.16575),
(-11.5567,25.4933,8.25302),
(-11.4734,30.3485,8.14915),
(-11.5115,32.2839,8.01367),
},{
(-8.79391,12.001,6.39481),
(-8.60483,14.7353,6.48022),
(-8.40905,21.277,6.64204),
(-8.57158,25.4933,6.70832),
(-8.45874,30.3485,6.62943),
(-8.51041,32.2839,6.52653)
}};
draw(P,uknot,vknot,new pen[] {red,green,blue,magenta});
// Rational Bezier patch:
// udegree=3, vdegree=3, nu=4, nv=4;
real[] uknot={0,0,0,0,1,1,1,1};
real[] vknot={0,0,0,0,1,1,1,1};
triple[][] P=scale3(20)*octant1.P;
// Optional weights:
real[][] weights=array(P.length,array(P[0].length,1.0));
weights[0][2]=5.0;
draw(P,uknot,vknot,weights,blue);
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