ADD 2D polygons winding directions.

Author: petrasvestartas

CHANGELOG.md

@@ -18,6 +18,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+* Add winding check in map_mesh function.
+
 ### Changed
 
 * Added meshpatter unify_cycles from COMPAS, LIBIGL has only triangle BFS.

mesh_flattened.json

@@ -44,7 +44,7 @@
 }
 
 
-def map_mesh(target_mesh, pattern_mesh, clip_boundaries=True, simplify_borders=True, fixed_vertices=None, tolerance=1e-6, unify_cycles=True):
+def map_mesh(target_mesh, pattern_mesh, clip_boundaries=True, simplify_borders=True, fixed_vertices=None, tolerance=1e-6):
     """
     Map a 2D pattern mesh onto a 3D target.
 
@@ -66,9 +66,6 @@ def map_mesh(target_mesh, pattern_mesh, clip_boundaries=True, simplify_borders=T
     tolerance : float, optional
         The tolerance for point comparison, to remove duplicates.
         Default is 1e-6.
-    unify_cycles : bool, optional
-        Whether to unify cycles of the pattern mesh.
-        Default is True.
 
     Returns
     -------
@@ -109,17 +106,11 @@ def map_mesh(target_mesh, pattern_mesh, clip_boundaries=True, simplify_borders=T
         v_numpy, f_numpy, pattern_v_numpy, pattern_f_vec, clip_boundaries, simplify_borders, fixed_vertices_vectorint, tolerance
     )
 
-    # LIBIGL has no BFS orienting for polygons, only triangles, so we copy here data several times:
-    if unify_cycles:
-        mesh = Mesh.from_vertices_and_faces(pv_numpy_copy, pf_numpy_cleaned)
-        mesh.unify_cycles()
-        pv_numpy_copy, pf_numpy_cleaned = mesh.to_vertices_and_faces()
-
     # Return the result as a tuple
     return pv_numpy_copy, pf_numpy_cleaned, p_normals, pattern_is_boundary, pattern_groups
 
 
-def map_pattern_to_mesh(name, mesh, clip_boundaries=True, tolerance=1e-6, pattern_u=16, pattern_v=16, simplify_borders=True, fixed_vertices=None, unify_cycles=True):
+def map_pattern_to_mesh(name, mesh, clip_boundaries=True, tolerance=1e-6, pattern_u=16, pattern_v=16, simplify_borders=True, fixed_vertices=None):
     """
     Map a 2D pattern mesh onto a 3D target.
 
@@ -167,9 +158,7 @@ def map_pattern_to_mesh(name, mesh, clip_boundaries=True, tolerance=1e-6, patter
     fixed_vertices : list[list[float]], optional
         A list of fixed points on the target mesh.
         Default is None.
-    unify_cycles : bool, optional
-        Whether to unify cycles of the pattern mesh.
-        Default is True.
+
     Returns
     -------
     compas.datastructures.Mesh
@@ -206,7 +195,7 @@ def map_pattern_to_mesh(name, mesh, clip_boundaries=True, tolerance=1e-6, patter
 
     v, f = mesh.to_vertices_and_faces()
     mapped_vertices, mapped_faces, mapped_normals, mapped_is_boundary, mapped_groups = map_mesh(
-        (v, f), (pv, pf), clip_boundaries=clip_boundaries, simplify_borders=simplify_borders, fixed_vertices=fixed_vertices, tolerance=tolerance, unify_cycles=unify_cycles
+        (v, f), (pv, pf), clip_boundaries=clip_boundaries, simplify_borders=simplify_borders, fixed_vertices=fixed_vertices, tolerance=tolerance
     )
 
     return Mesh.from_vertices_and_faces(mapped_vertices, mapped_faces)

src/compas_libigl/mapping.py

@@ -184,7 +184,29 @@ std::tuple<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor
     for (const auto &point_id : fixed_vertices){
         fixed.emplace_back(Clipper2Lib::PointD(flattned_target_uv(point_id, 0), flattned_target_uv(point_id, 1)));
     }
- 
+    
+    ////////////////////////////////////////////////////////////////////////////////////////
+    // Check and correct polygon orientations to ensure they're all counter-clockwise
+    ////////////////////////////////////////////////////////////////////////////////////////
+    std::vector<std::vector<int>> corrected_pattern_f = pattern_f;
+    
+    // Function to check if a polygon is counter-clockwise oriented
+    auto is_counter_clockwise = [&pattern_v](const std::vector<int>& face_indices) -> bool {
+        double sum = 0.0;
+        for (size_t i = 0; i < face_indices.size(); i++) {
+            sum += (pattern_v(face_indices[(i + 1) % face_indices.size()], 0) - pattern_v(face_indices[i], 0)) * 
+                  (pattern_v(face_indices[(i + 1) % face_indices.size()], 1) + pattern_v(face_indices[i], 1));
+        }
+        return sum < 0;
+    };
+    
+    // Check and correct orientations of all input polygon faces
+    for (size_t i = 0; i < corrected_pattern_f.size(); i++) {
+        if (!is_counter_clockwise(corrected_pattern_f[i])) {
+            std::reverse(corrected_pattern_f[i].begin(), corrected_pattern_f[i].end());
+        }
+    }
+    
     ////////////////////////////////////////////////////////////////////////////////////////
     // Get Boundary polygon of a Mesh as Clipper Path.
     ////////////////////////////////////////////////////////////////////////////////////////
@@ -215,7 +237,7 @@ std::tuple<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor
     std::vector<Clipper2Lib::PathsD> patterns_to_cut;
     std::vector<Clipper2Lib::PathsD> patterns_to_keep;
 
-    for (const auto &polyline_ids : pattern_f)
+    for (const auto &polyline_ids : corrected_pattern_f)
     {
 
         // Convert to clipper paths
@@ -422,6 +444,7 @@ std::tuple<Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic, Eigen::RowMajor
                 int idx = find_or_add_point(point.x, point.y);
                 face.push_back(idx);
             }
+            
             faces.push_back(face);
             groups.push_back(group_id);
             is_boundary.push_back(false);