Merge pull request #1158 from Geode-solutions/fix/update_polygon_sign_info

fix(polygon_sign): Updated code now that polygons are available as ba…

Author: MelchiorSchuh

include/geode/geometry/sign.hpp

@@ -28,7 +28,9 @@
 namespace geode
 {
     FORWARD_DECLARATION_DIMENSION_CLASS( Triangle );
+    FORWARD_DECLARATION_DIMENSION_CLASS( Polygon );
     ALIAS_2D_AND_3D( Triangle );
+    ALIAS_2D( Polygon );
     class Tetrahedron;
     enum struct SIDE;
     using Sign = SIDE;
@@ -48,6 +50,9 @@ namespace geode
     [[nodiscard]] Sign opengeode_geometry_api triangle_area_sign(
         const Triangle2D& triangle );
 
+    [[nodiscard]] Sign opengeode_geometry_api polygon_area_sign(
+        const Polygon2D& polygon );
+
     /*!
      * Return the sign of a 3D triangle area aligned on X- Y- or Z-axis.
      */

src/geode/geometry/sign.cpp

@@ -23,6 +23,7 @@
 
 #include <geode/geometry/sign.hpp>
 
+#include <geode/geometry/basic_objects/polygon.hpp>
 #include <geode/geometry/basic_objects/tetrahedron.hpp>
 #include <geode/geometry/basic_objects/triangle.hpp>
 #include <geode/geometry/internal/position_from_sides.hpp>
@@ -53,6 +54,24 @@ namespace geode
             GEO::PCK::orient_2d( vertices[0], vertices[1], vertices[2] ) );
     }
 
+    Sign polygon_area_sign( const Polygon2D& polygon )
+    {
+        const auto& polygon_vertices = polygon.vertices();
+        const auto& p1 = polygon_vertices[0];
+        for( const auto other_index : LRange{ 1, polygon_vertices.size() - 1 } )
+        {
+            const auto& p2 = polygon_vertices[other_index];
+            const auto& p3 = polygon_vertices[static_cast< local_index_t >(
+                other_index + 1 )];
+            const auto sign = triangle_area_sign( { p1, p2, p3 } );
+            if( sign != Sign::zero )
+            {
+                return sign;
+            }
+        }
+        return geode::Sign::zero;
+    }
+
     Sign triangle_area_sign( const Triangle3D& triangle, local_index_t axis )
     {
         const auto axis1 = new_axis[axis][0];

src/geode/mesh/helpers/repair_polygon_orientations.cpp

@@ -29,6 +29,7 @@
 
 #include <geode/basic/logger.hpp>
 
+#include <geode/geometry/basic_objects/polygon.hpp>
 #include <geode/geometry/basic_objects/triangle.hpp>
 #include <geode/geometry/information.hpp>
 #include <geode/geometry/sign.hpp>
@@ -143,31 +144,13 @@ namespace
             geode::Sign::zero };
         for( const auto polygon_id : geode::Range{ mesh.nb_polygons() } )
         {
-            const auto& p1 =
-                mesh.point( mesh.polygon_vertex( { polygon_id, 0 } ) );
-            for( const auto i :
-                geode::LRange{ 1, mesh.nb_polygon_vertices( polygon_id ) - 1 } )
+            area_sign_info.area_sign[polygon_id] =
+                geode::polygon_area_sign( mesh.polygon( polygon_id ) );
+            if( area_sign_info.area_sign[polygon_id] == geode::Sign::negative )
             {
-                const auto& p2 =
-                    mesh.point( mesh.polygon_vertex( { polygon_id, i } ) );
-                const auto& p3 = mesh.point( mesh.polygon_vertex( { polygon_id,
-                    static_cast< geode::local_index_t >( i + 1 ) } ) );
-                const auto sign = geode::triangle_area_sign( { p1, p2, p3 } );
-                if( sign == geode::Sign::positive )
-                {
-                    area_sign_info.area_sign[polygon_id] =
-                        geode::Sign::positive;
-                    break;
-                }
-                if( sign == geode::Sign::negative )
-                {
-                    area_sign_info.area_sign[polygon_id] =
-                        geode::Sign::negative;
-                    area_sign_info.nb_bad_polygons++;
-                    break;
-                }
+                area_sign_info.nb_bad_polygons++;
             }
-            if( area_sign_info.area_sign[polygon_id] == geode::Sign::zero )
+            else if( area_sign_info.area_sign[polygon_id] == geode::Sign::zero )
             {
                 area_sign_info.queue.emplace( polygon_id );
             }

tests/mesh/test-repair-polygon-orientations.cpp

@@ -163,7 +163,8 @@ void test()
     auto wrong_surface = build_bad_orientation_surface();
     wrong_surface->enable_edges();
     const auto edges_before = get_edges( *wrong_surface );
-    geode::repair_polygon_orientations( *wrong_surface );
+    auto builder = geode::SurfaceMeshBuilder2D::create( *wrong_surface );
+    geode::repair_polygon_orientations( *wrong_surface, *builder );
     check_repaired_surface( *wrong_surface );
     const auto edges_after = get_edges( *wrong_surface );
     compare_edges( edges_before, edges_after );