bool earQ(int i, int j, int k, const polygon& p)
{
triangle t(p.vec_points[i], p.vec_points[k], p.vec_points[k]);
if (cw(p.vec_points[i], p.vec_points[j], p.vec_points[k]))
return false;
for (int m = 0; m < p.get_n(); m++) {
if ((m != i) && (m != j) && (m != k))
if (t.contains(p.vec_points[m]))
return false;
}
return true;
}
///////////////////////////////////////////////////////////////////////////
// triangulation implementation
///////////////////////////////////////////////////////////////////////////
triangulation::triangulation(const polygon& p) {
int n = p.get_n();
vector<int> vleft(n), // left neighbor indices
vright(n); // rigth neighbor indices
for (int j = 0; j < n; j++) {
vleft[j] = ((j-1) + n) % n;
vright[j] = ((j+1) + n) % n;
}
int i = n - 1;
while ((int)vec_triangles.size() < (n-2)) {
i = vright[i];
if (earQ(vleft[i], i, vright[i], p)) {
triangle t(p.vec_points[vleft[i]], p.vec_points[i], p.vec_points[vright[i]]);
vec_triangles.push_back(t);
vleft[vright[i]] = vleft[i];
vright[vleft[i]] = vright[i];
}
}
}