Method buildBox

Engine/source/collision/polytope.cpp:48–128

// Box should be axis aligned in the transform space provided.

void Polytope::buildBox(const MatrixF& transform,const Box3F& box)
{
   // Box is assumed to be axis aligned in the source space.
   // Transform into geometry space
   Point3F xvec,yvec,zvec,min;
   transform.getColumn(0,&xvec);
   xvec *= box.len_x();
   transform.getColumn(1,&yvec);
   yvec *= box.len_y();
   transform.getColumn(2,&zvec);
   zvec *= box.len_z();
   transform.mulP(box.minExtents,&min);

   // Initial vertices
   mVertexList.setSize(8);
   mVertexList[0].point = min;
   mVertexList[1].point = min + yvec;
   mVertexList[2].point = min + xvec + yvec;
   mVertexList[3].point = min + xvec;
   mVertexList[4].point = mVertexList[0].point + zvec;
   mVertexList[5].point = mVertexList[1].point + zvec;
   mVertexList[6].point = mVertexList[2].point + zvec;
   mVertexList[7].point = mVertexList[3].point + zvec;
   S32 i;
   for (i = 0; i < 8; i++)
      mVertexList[i].side = 0;

   // Initial faces
   mFaceList.setSize(6);
   for (S32 f = 0; f < 6; f++) {
      Face& face = mFaceList[f];
      face.original = true;
      face.vertex = 0;
   }

   mFaceList[0].plane.set(mVertexList[0].point,xvec);
   mFaceList[0].plane.invert();
   mFaceList[1].plane.set(mVertexList[2].point,yvec);
   mFaceList[2].plane.set(mVertexList[2].point,xvec);
   mFaceList[3].plane.set(mVertexList[0].point,yvec);
   mFaceList[3].plane.invert();
   mFaceList[4].plane.set(mVertexList[0].point,zvec);
   mFaceList[4].plane.invert();
   mFaceList[5].plane.set(mVertexList[4].point,zvec);

   // Initial edges
   mEdgeList.setSize(12);
   Edge* edge = mEdgeList.begin();
   S32 nextEdge = 0;
   for (i = 0; i < 4; i++) {
      S32 n = (i == 3)? 0: i + 1;
      S32 p = (i == 0)? 3: i - 1;
      edge->vertex[0] = i;
      edge->vertex[1] = n;
      edge->face[0] = i;
      edge->face[1] = 4;
      edge->next = ++nextEdge;
      edge++;