fix: we can assume the arrangement to be triangular here or throw

Author: d-krupke

src/cgshop2026_pyutils/geometry/geometry_operations.cpp

@@ -129,7 +129,7 @@ static void build_arrangement_for_triangles(
 
 /**
  * Extract triangular faces from the arrangement.
- * Skips non-triangular faces and faces with vertices not in original point set.
+ * Expects that all bounded faces are triangles and will throw if not.
  */
 static std::vector<std::tuple<int, int, int>>
 extract_triangular_faces(
@@ -150,14 +150,13 @@ extract_triangular_faces(
     Halfedge_const_handle start = e;
 
     do {
-      if (deg > 3) break; // Early out: not a triangle
+      if (deg > 3) {throw std::runtime_error("Bound face is not triangular.");}; // Early out: not a triangle
 
       const Point &pv = e->source()->point();
       auto it = idx_of.find(pv);
       if (it == idx_of.end()) {
         // Vertex not in original points (likely intersection) - skip face
-        deg = 999;
-        break;
+        throw std::runtime_error("Face vertex not found in original points list.");
       }
       if (deg < 3) idxs[deg] = it->second;
       ++deg;
@@ -186,13 +185,11 @@ extract_triangular_faces(
  * convex hull. Otherwise, all edges should appear exactly twice. The indices
  * will be sorted in each triangle, and the list of triangles will also be
  * sorted.
+ * Expects that all bounded faces are triangles and will throw if not.
  */
 std::vector<std::tuple<int, int, int>>
 compute_triangles(const std::vector<Point> &points,
                   const std::vector<std::tuple<int, int>> &edges) {
-  std::cout << "Computing triangles from " << points.size() << " points and "
-            << edges.size() << " edges." << std::endl;
-
   // Step 1: Build point-to-index mapping
   std::map<Point, int, LessPointXY> idx_of;
   for (int i = 0; i < static_cast<int>(points.size()); ++i) {
@@ -208,11 +205,6 @@ compute_triangles(const std::vector<Point> &points,
   std::vector<std::tuple<int, int, int>> triangles =
       extract_triangular_faces(arrangement, idx_of);
 
-  // Step 4: Deduplicate and sort
-  std::sort(triangles.begin(), triangles.end());
-  triangles.erase(std::unique(triangles.begin(), triangles.end()),
-                  triangles.end());
-
   return triangles;
 }