bool TriangulatorAdaptor::triangulate(int *triangleIndexes) {
int XX, YY;
from3DTo2D(XX, YY);
map<pair<double, double> , int> coorToPosMap; // coordinate to position map
for (int i = 0; i < polygon.size(); i++) {
coorToPosMap.insert(
pair<pair<double, double> , int>(
pair<double, double>(polygon[i][XX], polygon[i][YY]), i));
}
TPPLPoly poly;
poly.Init(polygon.size());
for (int i = 0; i < polygon.size(); i++) {
poly[i].x = polygon[i][XX];
poly[i].y = polygon[i][YY];
}
if (poly.GetOrientation() == TPPL_CW) {
isClockwise = true;
poly.Invert(); // polygon has to be counter-clockwise
} else if(poly.GetOrientation() == TPPL_CCW) {
isClockwise = false;
} else {
return false;
}
list<TPPLPoly> triangles;
TPPLPartition triangulator; // see http://code.google.com/p/polypartition/
int success = triangulator.Triangulate_OPT(&poly, &triangles);
if (success != 1) {
cout << "Error: polygon cannot be triangulated!" << endl;
cout << "Polygon:" << endl;
for (int i=0; i<polygon.size(); i++) {
cout << polygon[i][0] << " " << polygon[i][1] << " " << polygon[i][2] << endl;
}
return false;
}
//assert(success == 1);
assert(triangles.size() +2 == polygon.size());
int count = 0;
for (list<TPPLPoly>::iterator it = triangles.begin(); it != triangles.end(); it++) {
if (!isClockwise) {
for (int j = 0; j < 3; j++) {
triangleIndexes[count * 3 + j] = coorToPosMap[pair<double, double>((*it)[j].x,
(*it)[j].y)];
}
} else {
for (int j = 0; j < 3; j++) {
triangleIndexes[count * 3 + 2 - j] = coorToPosMap[pair<double, double>((*it)[j].x,
(*it)[j].y)];
}
}
count++;
}
assert(count == triangles.size());
return true;
}
// Initialize polypartition TPPLPoly from a list of indices and vertices
//
// verts - 3D polygon vertex vectors
// xind,yind - Indices of 3D vectors to extract as x and y coordinates for 2D
// triangulation computation.
// inds,size - Array of indices into the `verts` list
// isHole - Value for the hole flag, and to determine the orientation
static void initTPPLPoly(TPPLPoly& poly,
const std::vector<float>& verts,
int xind, int yind,
const GLuint* inds, int size,
bool isHole)
{
// Check for explicitly closed polygons (last and first vertices equal) and
// discard the last vertex in these cases. This is a pretty stupid
// convention, but the OGC have blessed it and now we've got a bunch of
// geospatial formats (kml, WKT, GeoJSON) which require it. Sigh.
// http://gis.stackexchange.com/questions/10308/why-do-valid-polygons-repeat-the-same-start-and-end-point/10309#10309
if (inds[0] == inds[size-1] ||
(verts[3*inds[0]+0] == verts[3*inds[size-1]+0] &&
verts[3*inds[0]+1] == verts[3*inds[size-1]+1] &&
verts[3*inds[0]+2] == verts[3*inds[size-1]+2]))
{
g_logger.warning_limited("Ignoring duplicate final vertex in explicitly closed polygon");
size -= 1;
}
// Copy into polypartition data structure
poly.Init(size);
for (int i = 0; i < size; ++i)
{
poly[i].x = verts[3*inds[i]+xind];
poly[i].y = verts[3*inds[i]+yind];
poly[i].id = inds[i];
}
int orientation = poly.GetOrientation();
// Invert so that outer = ccw, holes = cw
if ((orientation == TPPL_CW) ^ isHole)
poly.Invert();
poly.SetHole(isHole);
}
void make_poly(float* buf, int pnt_sz, TPPLPoly& poly)
{
poly.Init(pnt_sz);
for (int k(0); k < pnt_sz; k++)
{
poly[k].x = buf[2 * k];
poly[k].y = buf[2 * k + 1];
}
if (poly.GetOrientation() == TPPL_CW)
{
poly.SetHole(true);
}
}
