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Diffstat (limited to 'Master/texmf-dist/doc/asymptote/examples/NURBSsphere.asy')
-rw-r--r-- | Master/texmf-dist/doc/asymptote/examples/NURBSsphere.asy | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/Master/texmf-dist/doc/asymptote/examples/NURBSsphere.asy b/Master/texmf-dist/doc/asymptote/examples/NURBSsphere.asy new file mode 100644 index 00000000000..5258c9986de --- /dev/null +++ b/Master/texmf-dist/doc/asymptote/examples/NURBSsphere.asy @@ -0,0 +1,46 @@ +import three; + +/* Reference: +@article{Qin97, + title={{Representing quadric surfaces using NURBS surfaces}}, + author={Qin, K.}, + journal={Journal of Computer Science and Technology}, + volume={12}, + number={3}, + pages={210--216}, + year={1997}, + publisher={Springer} +} +*/ + +size(10cm); +currentprojection=perspective(5,4,2,autoadjust=false); + +// udegree=2, vdegree=3, nu=3, nv=4; + +real[] W={2/3,1/3,1}; +real[] w={1,1/3,1/3,1}; + +// 10 distinct control points +triple[][] P={{(0,0,1),(-2,-2,1),(-2,-2,-1),(0,0,-1)}, + {(0,0,1),(2,-2,1),(2,-2,-1),(0,0,-1)}, + {(0,0,1),(2,2,1),(2,2,-1),(0,0,-1)}, + {(0,0,1),(-2,2,1),(-2,2,-1),(0,0,-1)}}; + +P.cyclic=true; + +real[][] weights=new real[3][4]; +for(int i=0; i < 3; ++i) +for(int j=0; j < 4; ++j) + weights[i][j]=W[i]*w[j]; + +real[] uknot={0,0,1/3,1/2,1,1}; +real[] vknot={0,0,0,0,1,1,1,1}; + +int N=1; + +for(int k=0; k < N; ++k) +for(int i=0; i < 4; ++i) + draw(shift(k*Z)*P[i:i+3],uknot,vknot,weights,blue); + +// draw(unitsphere,red+opacity(0.1)); |