//----------------------------------------------------------------------------
void ConvexPolyhedron::CreateEggShape (const Vector3& rkCenter, Real fX0,
Real fX1, Real fY0, Real fY1, Real fZ0, Real fZ1, int iMaxSteps,
ConvexPolyhedron& rkEgg)
{
assert( fX0 > 0.0f && fX1 > 0.0f );
assert( fY0 > 0.0f && fY1 > 0.0f );
assert( fZ0 > 0.0f && fZ1 > 0.0f );
assert( iMaxSteps >= 0 );
// Start with an octahedron whose 6 vertices are (-x0,0,0), (x1,0,0),
// (0,-y0,0), (0,y1,0), (0,0,-z0), (0,0,z1). The center point will be
// added later.
vector<Vector3> akPoint(6);
akPoint[0] = Vector3(-fX0,0.0f,0.0f);
akPoint[1] = Vector3(fX1,0.0f,0.0f);
akPoint[2] = Vector3(0.0f,-fY0,0.0f);
akPoint[3] = Vector3(0.0f,fY1,0.0f);
akPoint[4] = Vector3(0.0f,0.0f,-fZ0);
akPoint[5] = Vector3(0.0f,0.0f,fZ1);
vector<int> aiConnect(24);
aiConnect[ 0] = 1;
aiConnect[ 1] = 3;
aiConnect[ 2] = 5;
aiConnect[ 3] = 3;
aiConnect[ 4] = 0;
aiConnect[ 5] = 5;
aiConnect[ 6] = 0;
aiConnect[ 7] = 2;
aiConnect[ 8] = 5;
aiConnect[ 9] = 2;
aiConnect[10] = 1;
aiConnect[11] = 5;
aiConnect[12] = 3;
aiConnect[13] = 1;
aiConnect[14] = 4;
aiConnect[15] = 0;
aiConnect[16] = 3;
aiConnect[17] = 4;
aiConnect[18] = 2;
aiConnect[19] = 0;
aiConnect[20] = 4;
aiConnect[21] = 1;
aiConnect[22] = 2;
aiConnect[23] = 4;
rkEgg.InitialELabel() = 0;
rkEgg.Create(akPoint,aiConnect);
// Subdivide the triangles. The midpoints of the edges are computed.
// The triangle is replaced by four sub triangles using the original 3
// vertices and the 3 new edge midpoints.
int i;
for (int iStep = 1; iStep <= iMaxSteps; iStep++)
{
int iVQuantity = rkEgg.GetVQuantity();
int iEQuantity = rkEgg.GetEQuantity();
int iTQuantity = rkEgg.GetTQuantity();
// compute lifted edge midpoints
for (i = 0; i < iEQuantity; i++)
{
// get edge
const MTEdge& rkE = rkEgg.GetEdge(i);
int iV0 = rkEgg.GetVLabel(rkE.GetVertex(0));
int iV1 = rkEgg.GetVLabel(rkE.GetVertex(1));
// compute "lifted" centroid to points
Vector3 kCen = rkEgg.Point(iV0)+rkEgg.Point(iV1);
Real fXR = (kCen.x > 0.0f ? kCen.x/fX1 : kCen.x/fX0);
Real fYR = (kCen.y > 0.0f ? kCen.y/fY1 : kCen.y/fY0);
Real fZR = (kCen.z > 0.0f ? kCen.z/fZ1 : kCen.z/fZ0);
kCen *= Math::InvSqrt(fXR*fXR+fYR*fYR+fZR*fZR);
// Add the point to the array. Store the point index in the edge
// label for support in adding new triangles.
rkEgg.ELabel(i) = iVQuantity++;
rkEgg.AddPoint(kCen);
}
// Add the new triangles and remove the old triangle. The removal
// in slot i will cause the last added triangle to be moved to that
// slot. This side effect will not interfere with the iteration
// and removal of the triangles.
for (i = 0; i < iTQuantity; i++)
{
const MTTriangle& rkT = rkEgg.GetTriangle(i);
int iV0 = rkEgg.GetVLabel(rkT.GetVertex(0));
int iV1 = rkEgg.GetVLabel(rkT.GetVertex(1));
int iV2 = rkEgg.GetVLabel(rkT.GetVertex(2));
int iV01 = rkEgg.GetELabel(rkT.GetEdge(0));
int iV12 = rkEgg.GetELabel(rkT.GetEdge(1));
int iV20 = rkEgg.GetELabel(rkT.GetEdge(2));
rkEgg.Insert(iV0,iV01,iV20);
rkEgg.Insert(iV01,iV1,iV12);
rkEgg.Insert(iV20,iV12,iV2);
rkEgg.Insert(iV01,iV12,iV20);
rkEgg.Remove(iV0,iV1,iV2);
}
}
// add center
for (i = 0; i < (int)rkEgg.m_akPoint.size(); i++)
rkEgg.m_akPoint[i] += rkCenter;
rkEgg.UpdatePlanes();
}
