包围球的计算

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//【Ritter90】逼近包围球的计算----------------------------------------------------------------------//查找相隔最远的两个顶点void MostSeparatedPointsOnAABB(int &imin, int &imax, Vector3 pt[], int numPts){int minx = 0, maxx = 0, miny = 0, maxy = 0, minz = 0, maxz = 0;for(unsigned int i = 1; i <numPts; ++i){if(pt[i].x < pt[minx].x) minx = i;if(pt[i].x > pt[maxx].x) maxx = i;if(pt[i].y < pt[miny].y) miny = i;if(pt[i].y > pt[maxy].y) maxy = i;if(pt[i].z < pt[minz].z) minz = i;if(pt[i].z > pt[maxz].z) maxz = i;}float dist2x = (pt[maxx]-pt[minx]).dotProduct(pt[maxx]-pt[minx]);float dist2y = (pt[maxy]-pt[miny]).dotProduct(pt[maxy]-pt[miny]);float dist2z = (pt[maxz]-pt[minz]).dotProduct(pt[maxz]-pt[minz]);imin = minx;imax = maxx;if(dist2y > dist2x && dist2y > dist2z){imin = miny;imax = maxy;}if(dist2z > dist2x && dist2z > dist2y){imin = minz;imax = maxz;}}//计算包围球的半径和球心void SphereFromDistantPoints(Sphere &s, Vector3 pt[], int numPts){int imin, imax;MostSeparatedPointsOnAABB(imin, imax, pt, numPts);s.center = ((pt[imin] + pt[imax]) * 0.5f);s.r = (pt[imax] - s.center).dotProduct(pt[imax] - s.center);s.r = Math::Sqrt(s.r);}//循环所有顶点更新包围球体void SphereOfSphereAndPt(Sphere &s, Vector3 &p){Vector3 d = p-s.center;float dist2 = d.dotProduct(d);if(dist2 > s.r * s.r){float dist = Math::Sqrt(dist2);float newRadius = (s.r + dist) * 0.5f;float k = (newRadius - s.r) / dist;s.r = newRadius;s.center += d * k;}}//综合上述过程计算包围球void RitterSphere(Sphere &s, Vector3 pt[], int numPts){SphereFromDistantPoints(s, pt, numPts);for(unsigned int i = 0; i < numPts; ++i)SphereOfSphereAndPt(s, pt[i]);}
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