/** Initialise the list of faces for the mesh
*
* \param nverts - number of vertices per face
* \param verts - concatenated array of vertex indices into the primvar arrays.
* \param faces - newly initialised faces go here.
*/
void EmitterMesh::createFaceList(const Ri::IntArray& nverts,
const Ri::IntArray& verts,
FaceVec& faces) const
{
// Create face list
int faceStart = 0;
float totWeight = 0;
int sizeNVerts = nverts.size();
int totVerts = 0;
faces.reserve(sizeNVerts);
for(int i = 0; i < sizeNVerts; ++i)
{
if(nverts[i] != 3 && nverts[i] != 4)
{
assert(0 && "emitter mesh can only deal with 3 and 4-sided faces");
continue;
}
faces.push_back(MeshFace(&verts[0]+faceStart, totVerts, nverts[i]));
faceStart += nverts[i];
// Get weight for face
float w = faceArea(faces.back());
faces.back().weight = w;
totWeight += w;
totVerts += nverts[i];
}
// normalized areas so that total area = 1.
float scale = 1/totWeight;
for(int i = 0; i < sizeNVerts; ++i)
faces[i].weight *= scale;
}
//giving a point, find out which cell contains this point
//since the number of cells is not large, we search by loop over all cells
vector<int>
Grid::findNeighborsByCells(const VecD3& point)
{
vector<int> neighborList;
const int nCells = _cells.getCount();
const CRConnectivity& cellNodes = *_cellNodes;
const Array<VecD3>& nodeCoords = *_coordinates;
for ( int c=0; c<nCells; c++){
const int nsize = cellNodes.getCount(c);
int node[nsize];
for(int n=0; n<nsize; n++){
node[n] = cellNodes(c,n);
}
Array<VecD3> faceArea(nsize);
Array<VecD3> faceCentroid(nsize);
for(int n=0; n<nsize-1; n++){
faceArea[n]=nodeCoords[node[n+1]]-nodeCoords[node[n]];
faceCentroid[n]=(nodeCoords[node[n+1]]+nodeCoords[node[n]])/2.;
}
faceArea[nsize-1]=nodeCoords[node[0]]-nodeCoords[node[nsize-1]];
faceCentroid[nsize-1]=(nodeCoords[node[0]]+nodeCoords[node[nsize-1]])/2.;
int find = 1;
for(int n=0; n<nsize; n++){
VecD3 faceNorm;
faceNorm[0]=faceArea[n][1];
faceNorm[1]=-faceArea[n][0];
faceNorm[2]=faceArea[n][2];
VecD3 dr = point - faceCentroid[n];
dr[2] = 0.0; //difference in z direction is neglected. just check x-y plane
if (dot(faceNorm,dr) > 0.0) {
find = 0;
break;
}
}
//point falls into a cell
if (find){
for(int n=0; n<nsize; n++){
node[n]=cellNodes(c,n);
neighborList.push_back(node[n]);
}
return(neighborList);
}
}
//point falls outside of grid boundary
//find the cloest cell to this point
//use that cell to interpolate
double distMin = 1.0e10;
int closestCell = 0;
for ( int c=0; c<nCells; c++){
const int nsize = cellNodes.getCount(c);
VecD3 cellCentroid;
cellCentroid[0]=0.0;
cellCentroid[1]=0.0;
cellCentroid[2]=0.0;
for(int n=0; n<nsize; n++){
cellCentroid += nodeCoords[cellNodes(c,n)];
}
cellCentroid /= 3.;
VecD3 dr = point - cellCentroid;
double distance = mag(dr);
if(distance < distMin){
distMin = distance;
closestCell = c;
}
}
const int nsize = cellNodes.getCount(closestCell);
for(int n=0; n<nsize; n++){
neighborList.push_back(cellNodes(closestCell,n));
}
return(neighborList);
}
