//----------------------------------------------------------------------------
void MTMesh::AttachTriangleToEdge (int t, MTTriangle& triangle, int i, int e,
MTEdge& edge)
{
if (edge.Triangle(0) == -1)
{
edge.Triangle(0) = t;
}
else
{
int a = edge.Triangle(0);
MTTriangle& adjacent = mTriangles[a];
triangle.Adjacent(i) = a;
for (int j = 0; j < 3; ++j)
{
if (adjacent.Edge(j) == e)
{
adjacent.Adjacent(j) = t;
break;
}
}
if (edge.Triangle(1) == -1)
{
edge.Triangle(1) = t;
}
else
{
assertion(false, "The mesh is not manifold.\n");
}
}
triangle.Edge(i) = e;
}
//----------------------------------------------------------------------------
void MTMesh::AttachTriangleToEdge (int iT, MTTriangle& rkT, int i, int iE,
MTEdge& rkE)
{
if ( rkE.Triangle(0) == -1 )
{
rkE.Triangle(0) = iT;
}
else
{
int iTAdj = rkE.Triangle(0);
MTTriangle& rkTAdj = m_akTriangle[iTAdj];
rkT.Adjacent(i) = iTAdj;
for (int j = 0; j < 3; j++)
{
if ( rkTAdj.Edge(j) == iE )
{
rkTAdj.Adjacent(j) = iT;
break;
}
}
if ( rkE.Triangle(1) == -1 )
{
rkE.Triangle(1) = iT;
}
else
{
// mesh is not manifold
assert( false );
}
}
rkT.Edge(i) = iE;
}
//----------------------------------------------------------------------------
void MTMesh::DetachTriangleFromEdge (int t, MTTriangle& triangle, int i,
int e, MTEdge& edge)
{
// This function leaves T only partially complete. The edge E is no
// longer referenced by T, even though the vertices of T reference the
// end points of E. If T has an adjacent triangle A that shares E, then
// A is a complete triangle.
if (edge.Triangle(0) == t)
{
int a = edge.Triangle(1);
if (a != -1)
{
// T and TAdj share E, update adjacency information for both
MTTriangle& adjacent = mTriangles[a];
for (int j = 0; j < 3; ++j)
{
if (adjacent.Edge(j) == e)
{
adjacent.Adjacent(j) = -1;
break;
}
}
}
edge.Triangle(0) = a;
}
else if (edge.Triangle(1) == t)
{
// T and TAdj share E, update adjacency information for both
MTTriangle& adjacent = mTriangles[edge.Triangle(0)];
for (int j = 0; j < 3; ++j)
{
if (adjacent.Edge(j) == e)
{
adjacent.Adjacent(j) = -1;
break;
}
}
}
else
{
// Should not get here. The specified edge must share the input
// triangle.
assertion(false, "Unexpected condition.\n");
}
edge.Triangle(1) = -1;
triangle.Edge(i) = -1;
triangle.Adjacent(i) = -1;
}
//----------------------------------------------------------------------------
void MTMesh::DetachTriangleFromEdge (int iT, MTTriangle& rkT, int i, int iE,
MTEdge& rkE)
{
// This function leaves T only partially complete. The edge E is no
// longer referenced by T, even though the vertices of T reference the
// end points of E. If T has an adjacent triangle A that shares E, then
// A is a complete triangle.
if ( rkE.Triangle(0) == iT )
{
int iTAdj = rkE.Triangle(1);
if ( iTAdj != -1 )
{
// T and TAdj share E, update adjacency information for both
MTTriangle& rkTAdj = m_akTriangle[iTAdj];
for (int j = 0; j < 3; j++)
{
if ( rkTAdj.Edge(j) == iE )
{
rkTAdj.Adjacent(j) = -1;
break;
}
}
}
rkE.Triangle(0) = iTAdj;
}
else if ( rkE.Triangle(1) == iT )
{
// T and TAdj share E, update adjacency information for both
MTTriangle& rkTAdj = m_akTriangle[rkE.Triangle(0)];
for (int j = 0; j < 3; j++)
{
if ( rkTAdj.Edge(j) == iE )
{
rkTAdj.Adjacent(j) = -1;
break;
}
}
}
else
{
// Should not get here. The specified edge must share the input
// triangle.
assert( false );
}
rkE.Triangle(1) = -1;
rkT.Edge(i) = -1;
rkT.Adjacent(i) = -1;
}
//----------------------------------------------------------------------------
void ConvexPolyhedron::ComputeTerminator (const Vector3& rkEye,
vector<Vector3>& rkTerminator)
{
// temporary storage for signed distances from eye to triangles
int iTQuantity = m_akTriangle.GetQuantity();
vector<Real> afDistance(iTQuantity);
int i, j;
for (i = 0; i < iTQuantity; i++)
afDistance[i] = Math::MAX_REAL;
// Start a search for a front-facing triangle that has an adjacent
// back-facing triangle or for a back-facing triangle that has an
// adjacent front-facing triangle.
int iTCurrent = 0;
MTTriangle* pkTCurrent = &m_akTriangle[iTCurrent];
Real fTriDist = GetDistance(rkEye,iTCurrent,afDistance);
int iEFirst = -1;
for (i = 0; i < iTQuantity; i++)
{
// Check adjacent neighbors for edge of terminator. Such an
// edge occurs if the signed distance changes sign.
int iMinIndex = -1;
Real fMinAbsDist = Math::MAX_REAL;
Real afAdjDist[3];
for (j = 0; j < 3; j++)
{
afAdjDist[j] = GetDistance(rkEye,pkTCurrent->Adjacent(j),
afDistance);
if ( IsNegativeProduct(fTriDist,afAdjDist[j]) )
{
iEFirst = pkTCurrent->Edge(j);
break;
}
Real fAbsDist = Math::FAbs(afAdjDist[j]);
if ( fAbsDist < fMinAbsDist )
{
fMinAbsDist = fAbsDist;
iMinIndex = j;
}
}
if ( j < 3 )
break;
// First edge not found during this iteration. Move to adjacent
// triangle whose distance is smallest of all adjacent triangles.
iTCurrent = pkTCurrent->Adjacent(iMinIndex);
pkTCurrent = &m_akTriangle[iTCurrent];
fTriDist = afAdjDist[iMinIndex];
}
assert( i < iTQuantity );
MTEdge& rkEFirst = m_akEdge[iEFirst];
rkTerminator.push_back(m_akPoint[GetVLabel(rkEFirst.Vertex(0))]);
rkTerminator.push_back(m_akPoint[GetVLabel(rkEFirst.Vertex(1))]);
// walk along the terminator
int iVFirst = rkEFirst.Vertex(0);
int iV = rkEFirst.Vertex(1);
int iE = iEFirst;
int iEQuantity = m_akEdge.GetQuantity();
for (i = 0; i < iEQuantity; i++)
{
// search all edges sharing the vertex for another terminator edge
int j, jMax = m_akVertex[iV].GetEdgeQuantity();
for (j = 0; j < m_akVertex[iV].GetEdgeQuantity(); j++)
{
int iENext = m_akVertex[iV].GetEdge(j);
if ( iENext == iE )
continue;
Real fDist0 = GetDistance(rkEye,m_akEdge[iENext].GetTriangle(0),
afDistance);
Real fDist1 = GetDistance(rkEye,m_akEdge[iENext].GetTriangle(1),
afDistance);
if ( IsNegativeProduct(fDist0,fDist1) )
{
if ( m_akEdge[iENext].GetVertex(0) == iV )
{
iV = m_akEdge[iENext].GetVertex(1);
rkTerminator.push_back(m_akPoint[GetVLabel(iV)]);
if ( iV == iVFirst )
return;
}
else
{
iV = m_akEdge[iENext].GetVertex(0);
rkTerminator.push_back(m_akPoint[GetVLabel(iV)]);
if ( iV == iVFirst )
return;
}
iE = iENext;
break;
}
}
assert( j < jMax );
}
assert( i < iEQuantity );
}
