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mytritri.cpp

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00001 #include "sysdep.h"
00002 #include "mytritri.h"
00003 
00004 Vector3D my_tri_tri_intersect(const Triangle& t1, const Triangle& t2)
00005 {
00006   Plane p1(t1.v1,t1.v2,t1.v3);
00007   int other_side=0;
00008   {
00009     float f1=p1.Classify(t2.v1);
00010     float f2=p1.Classify(t2.v2);
00011     float f3=p1.Classify(t2.v3);
00012     float f12=f1*f2;
00013     float f23=f2*f3;
00014     if (f12>0.0f && f23>0.0f) return Vector3D::Zero;
00015     other_side=(f12<0.0f?(f23<0.0f?1:0):2);
00016   }
00017   Plane p2(t2.v1,t2.v2,t2.v3);
00018   Vector3D n12(p1.normal+p2.normal);
00019   TriangleDesc td2(t2,p2);
00020   const Vector3D& a2=td2[other_side+1];
00021   const Vector3D& b2=td2[other_side];
00022   const Vector3D& c2=td2[other_side+2];
00023   float t21=-(p1.d+p2.d+a2*n12)/((b2-a2)*n12);
00024   TriangleDesc td1(t1,p1);
00025   Vector3D P21(a2+t21*(b2-a2));
00026   if (td1.pointInTri(P21)) return P21;
00027   float t22=-(p1.d+p2.d+c2*n12)/((b2-c2)*n12);
00028   Vector3D P22(c2+t22*(b2-c2));
00029   if (td1.pointInTri(P22)) return P22;
00030 
00031   {
00032     float f1=p2.Classify(t1.v1);
00033     float f2=p2.Classify(t1.v2);
00034     float f3=p2.Classify(t1.v3);
00035     float f12=f1*f2;
00036     float f23=f2*f3;
00037     if (f12>0.0f && f23>0.0f) return Vector3D::Zero;
00038     other_side=(f12<0.0f?(f23<0.0f?1:0):2);
00039   }
00040   const Vector3D& a1=td1[other_side+1];
00041   const Vector3D& b1=td1[other_side];
00042   const Vector3D& c1=td1[other_side+2];
00043   float t11=-(p1.d+p2.d+a1*n12)/((b1-a1)*n12);
00044   Vector3D P11(a1+t11*(b1-a1));
00045   if (td2.pointInTri(P11)) return P11;
00046   float t12=-(p1.d+p2.d+c1*n12)/((b1-c1)*n12);
00047   Vector3D P12(c1+t12*(b1-c1));
00048   if (td2.pointInTri(P12)) return P12;
00049   return Vector3D::Zero;
00050 }

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