From d7c5eb2405eb0ba536b194b7831e58a5cb196383 Mon Sep 17 00:00:00 2001
From: Chris <chris@ladybug.tools>
Date: Fri, 24 Nov 2023 10:50:27 -0500
Subject: [PATCH] fix(shademesh): Change method to only traingulate non planar
 quads

---
 honeybee/shademesh.py   | 28 +++++++++++++++++-------
 tests/shademesh_test.py | 47 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 8 deletions(-)

diff --git a/honeybee/shademesh.py b/honeybee/shademesh.py
index 3a9b98ae..6e37ede7 100644
--- a/honeybee/shademesh.py
+++ b/honeybee/shademesh.py
@@ -219,7 +219,7 @@ def scale(self, factor, origin=None):
         self.properties.scale(factor, origin)
 
     def triangulate_and_remove_degenerate_faces(self, tolerance=0.01):
-        """Triangulate all faces in the mesh and remove all degenerate faces from the result.
+        """Triangulate non-planar faces in the mesh and remove all degenerate faces.
 
         This is helpful for certain geometry interfaces that require perfectly
         planar geometry without duplicate or colinear vertices.
@@ -231,16 +231,28 @@ def triangulate_and_remove_degenerate_faces(self, tolerance=0.01):
         """
         new_faces, verts = [], self.geometry.vertices
         for shd in self.faces:
-            shades = (shd,) if len(shd) == 3 else \
-                ((shd[0], shd[1], shd[2]), (shd[2], shd[3], shd[0]))
-            for shade in enumerate(shades):
-                shd_verts = [verts[v] for v in shade]
-                shade_face = Face3D(shd_verts)
+            shd_verts = [verts[v] for v in shd]
+            shf = Face3D(shd_verts)
+            if not shf.check_planar(tolerance, raise_exception=False):
+                shades = ((shd[0], shd[1], shd[2]), (shd[2], shd[3], shd[0]))
+                for shade in shades:
+                    shd_verts = [verts[v] for v in shade]
+                    shade_face = Face3D(shd_verts)
+                    try:
+                        shade_face.remove_colinear_vertices(tolerance)
+                    except AssertionError:
+                        continue  # degenerate face to remove
+                    new_faces.append(shade)
+            else:
                 try:
-                    shade_face.remove_colinear_vertices(tolerance)
+                    new_face = shf.remove_colinear_vertices(tolerance)
                 except AssertionError:
                     continue  # degenerate face to remove
-                new_faces.append(shade)
+                if len(new_face.vertices) == len(shd):
+                    new_faces.append(shd)
+                else:  # quad face with duplicate or colinear verts
+                    new_sh = tuple(shd[shd_verts.index(v)] for v in new_face.vertices)
+                    new_faces.append(new_sh)
         self._geometry = Mesh3D(verts, new_faces)
 
     def is_geo_equivalent(self, shade_mesh, tolerance=0.01):
diff --git a/tests/shademesh_test.py b/tests/shademesh_test.py
index 5740c963..1756b46e 100644
--- a/tests/shademesh_test.py
+++ b/tests/shademesh_test.py
@@ -175,6 +175,53 @@ def test_reflect():
     assert test_2.geometry[2].z == pytest.approx(2, rel=1e-3)
 
 
+def test_triangulate_and_remove_degenerate_faces():
+    """Test the triangulate_and_remove_degenerate_faces method."""
+    pts = (Point3D(0, 0, 4), Point3D(0, 2, 4), Point3D(2, 2, 4),
+           Point3D(2, 0, 4), Point3D(4, 0, 4))
+    mesh = Mesh3D(pts, [(0, 1, 2, 3), (2, 3, 4)])
+    shade = ShadeMesh('Awning_1', mesh)
+    shade.triangulate_and_remove_degenerate_faces(0.01)
+    assert len(shade.faces) == 2
+    assert len(shade.faces[0]) == 4
+    assert len(shade.faces[1]) == 3
+
+    pts = (Point3D(0, 0, 2), Point3D(0, 2, 4), Point3D(2, 2, 4),
+           Point3D(2, 0, 4), Point3D(4, 0, 4))
+    mesh = Mesh3D(pts, [(0, 1, 2, 3), (2, 3, 4)])
+    shade = ShadeMesh('Awning_1', mesh)
+    shade.triangulate_and_remove_degenerate_faces(0.01)
+    assert len(shade.faces) == 3
+    assert len(shade.faces[0]) == 3
+    assert len(shade.faces[1]) == 3
+
+    pts = (Point3D(0, 2, 4), Point3D(0, 2, 4), Point3D(2, 2, 4),
+           Point3D(2, 0, 4), Point3D(4, 0, 4))
+    mesh = Mesh3D(pts, [(0, 1, 2, 3), (2, 3, 4)])
+    shade = ShadeMesh('Awning_1', mesh)
+    shade.triangulate_and_remove_degenerate_faces(0.01)
+    assert len(shade.faces) == 2
+    assert len(shade.faces[0]) == 3
+    assert len(shade.faces[1]) == 3
+
+    pts = (Point3D(0, 0, 4), Point3D(0, 2, 4), Point3D(2, 2, 4),
+           Point3D(2, 0, 4), Point3D(2, 0, 4))
+    mesh = Mesh3D(pts, [(0, 1, 2, 3), (2, 3, 4)])
+    shade = ShadeMesh('Awning_1', mesh)
+    shade.triangulate_and_remove_degenerate_faces(0.01)
+    assert len(shade.faces) == 1
+    assert len(shade.faces[0]) == 4
+
+    pts = (Point3D(1, 1, 4), Point3D(0, 2, 4), Point3D(2, 2, 4),
+           Point3D(2, 0, 4), Point3D(4, 0, 4))
+    mesh = Mesh3D(pts, [(0, 1, 2, 3), (2, 3, 4)])
+    shade = ShadeMesh('Awning_1', mesh)
+    shade.triangulate_and_remove_degenerate_faces(0.01)
+    assert len(shade.faces) == 2
+    assert len(shade.faces[0]) == 3
+    assert len(shade.faces[1]) == 3
+
+
 def test_to_dict():
     """Test the shade to_dict method."""
     pts = (Point3D(0, 0, 4), Point3D(0, 2, 4), Point3D(2, 2, 4),