real SVertex::GetIsophoteDistance(real isovalue, int maxDistance) const
{
if (_sourceVertex == NULL && _sourceEdge == NULL)
return -1; // not handling the case of intersection SVertices yet
if (!(getNature() & Nature::SILHOUETTE)) // only handle silhouette curves
return -1;
Vec3r startPoint = _Point3D;
set<pair<WFace*,int> > possibleStartEdges;
real currentNdotV;
// if (!(getNature() & Nature::SURFACE_INTERSECTION))
// printf("Isophote search Nature: %d\n", getNature());
if (_sourceVertex != NULL)
{
currentNdotV = _sourceVertex->GetSurfaceNdotV();
// printf("Starting at vertex with n dot v = %f\n", currentNdotV);
for(vector<WEdge*>::iterator it = _sourceVertex->GetEdges().begin(); it != _sourceVertex->GetEdges().end(); ++it)
{
WFace * aface = (*it)->GetaFace();
WFace * bface = (*it)->GetbFace();
if (aface != NULL)
possibleStartEdges.insert( pair<WFace*,int>(aface, (aface->GetIndex(_sourceVertex)+1)%3));
if (bface != NULL)
possibleStartEdges.insert(pair<WFace*,int>(bface, (bface->GetIndex(_sourceVertex)+1)%3));
}
}
else
{
currentNdotV = ComputeSurfaceNdotV(_sourceEdge, startPoint);
WFace * faces[2] = { _sourceEdge->GetaFace(), _sourceEdge->GetbFace() };
for(int i=0;i<2;i++)
if (faces[i] != NULL)
{
int v;
for(v=0;v<3;v++)
if (faces[i]->GetOEdge(v)->GetOwner() == _sourceEdge)
break;
assert(v<3);
possibleStartEdges.insert(pair<WFace*,int>(faces[i], (v+1)%3));
possibleStartEdges.insert(pair<WFace*,int>(faces[i], (v+2)%3));
}
}
if (currentNdotV > isovalue)
return 0;
if (currentNdotV < -0.001)
return 0;
Vec3r currentPoint;
WEdge * currentEdge = NULL;
WFace * currentFace = NULL;
Vec3r lastPoint = startPoint;
real lastNdotV = currentNdotV;
for(set<pair<WFace*,int> >::iterator it = possibleStartEdges.begin(); it != possibleStartEdges.end(); ++it)
{
WFace * face = (*it).first;
int e = (*it).second;
if (AdvanceToEdge( face, startPoint, e, currentPoint))
{
currentNdotV = ComputeSurfaceNdotV(face->GetOEdge(e)->GetOwner(), currentPoint);
// printf("\tlastNdotV = %f, currentNdotV = %f\n", lastNdotV, currentNdotV);
if (currentNdotV < lastNdotV)
continue;
currentEdge = face->GetOEdge(e)->GetOwner();
currentFace = face->GetBordingFace(e);
assert(GeomUtils::distPointSegment<Vec3r>( currentPoint, currentEdge->GetaVertex()->GetVertex(), currentEdge->GetbVertex()->GetVertex()) < 0.01);
break;
}
}
if (currentEdge == NULL)
return -1;
// march over the surface
int numSteps = 0;
while (currentNdotV < isovalue && currentNdotV > -0.001 && numSteps < 100 && currentFace != NULL && ImageSpaceDistance(startPoint, currentPoint) < maxDistance)
{
numSteps ++;
lastPoint = currentPoint;
lastNdotV = currentNdotV;
// printf("advancing, current NdotV = %f\n", currentNdotV);
bool result = false;
int e;
Vec3r nextPoint;
for(e=0;e<3;e++)
{
if (currentFace->GetOEdge(e)->GetOwner() == currentEdge)
continue;
result = AdvanceToEdge(currentFace, currentPoint, e, nextPoint);
// printf("\t advance result = %s\n", result ? "true" : "false");
if (result)
break;
}
assert(result);
currentPoint = nextPoint;
currentEdge = currentFace->GetOEdge(e)->GetOwner();
currentNdotV = ComputeSurfaceNdotV(currentEdge, currentPoint);
currentFace = currentFace->GetBordingFace(e);
}
Vec3r endpoint;
if (currentNdotV > isovalue)
{
real t = (isovalue - lastNdotV)/(currentNdotV - lastNdotV);
endpoint = (1-t) * lastPoint + t * currentPoint;
}
else
if (currentNdotV < -0.001)
{
real t = -lastNdotV/(currentNdotV - lastNdotV); // endpoint is the zero-crossing
endpoint = (1-t)*lastPoint + t * currentPoint;
}
else
endpoint = currentPoint;
ViewMap * vm = ViewMap::getInstance();
vm->addDebugPoint(DebugPoint::ISOPHOTE, endpoint, startPoint);
real dist = ImageSpaceDistance(startPoint, endpoint);
// printf("\t result: dist = %f, lastNdotV = %f, currentNdotV = %f, numSteps = %d, currentFace = %08X\n", dist, lastNdotV, currentNdotV, numSteps, currentFace);
return dist;
}
