Smooth quads (#793)

* switched to ivec4, tests still pass

* added partition quad support

* added quad support for property interp

* forming quad tangents

* convex barycentric

* fix interpolation

* added linear quad interp

* added quad smoothing

* fixed vec out of range

* all tests pass

* fixed quad tangents

* tightened quad test

* cleanup

* avoid dome duplicate work

* added docs

* update test

Author: elalish

.vscode/launch.json

@@ -12,7 +12,7 @@
       "program": "${workspaceFolder}/build/test/manifold_test",
       "args": [
         "--gtest_break_on_failure",
-        "--gtest_filter=Manifold.HullFail"
+        "--gtest_filter=Manifold.RefineQuads"
       ],
       "stopAtEntry": false,
       "cwd": "${workspaceFolder}/build/test",

.vscode/settings.json

@@ -150,4 +150,4 @@
   },
   "python.formatting.provider": "none",
   "clang-format.executable": "clang-format",
-}
+}

CMakeLists.txt

@@ -91,7 +91,7 @@ else()
   else()
     set(WARNING_FLAGS -Werror -Wall -Wno-sign-compare -Wno-unused)
   endif()
-  set(MANIFOLD_FLAGS ${MANIFOLD_FLAGS} ${WARNING_FLAGS} -O3)
+  set(MANIFOLD_FLAGS ${MANIFOLD_FLAGS} ${WARNING_FLAGS})
 endif()
 
 if(CODE_COVERAGE AND NOT MSVC)

src/manifold/src/impl.h

@@ -42,6 +42,9 @@ struct Manifold::Impl {
     Vec<TriRef> triRef;
     Vec<glm::ivec3> triProperties;
   };
+  struct BaryIndices {
+    int tri, start4, end4;
+  };
 
   Box bBox_;
   float precision_ = -1;
@@ -161,7 +164,13 @@ struct Manifold::Impl {
   void SplitPinchedVerts();
 
   // smoothing.cu
+  bool IsInsideQuad(int halfedge) const;
+  bool IsMarkedInsideQuad(int halfedge) const;
   glm::vec3 GetNormal(int halfedge, int normalIdx) const;
+  int GetNeighbor(int tri) const;
+  glm::ivec4 GetHalfedges(int tri) const;
+  BaryIndices GetIndices(int halfedge) const;
+  void FillRetainedVerts(Vec<Barycentric>& vertBary) const;
   std::vector<Smoothness> UpdateSharpenedEdges(
       const std::vector<Smoothness>&) const;
   Vec<bool> FlatFaces() const;

src/manifold/src/manifold.cpp

@@ -681,7 +681,8 @@ Manifold Manifold::CalculateNormals(int normalIdx, float minSharpAngle) const {
  * Smooths out the Manifold by filling in the halfedgeTangent vectors. The
  * geometry will remain unchanged until Refine or RefineToLength is called to
  * interpolate the surface. This version uses the supplied vertex normal
- * properties to define the tangent vectors.
+ * properties to define the tangent vectors. Faces of two coplanar triangles
+ * will be marked as quads, while faces with three or more will be flat.
  *
  * @param normalIdx The first property channel of the normals. NumProp must be
  * at least normalIdx + 3. Any vertex where multiple normals exist and don't
@@ -699,7 +700,8 @@ Manifold Manifold::SmoothByNormals(int normalIdx) const {
  * Smooths out the Manifold by filling in the halfedgeTangent vectors. The
  * geometry will remain unchanged until Refine or RefineToLength is called to
  * interpolate the surface. This version uses the geometry of the triangles and
- * pseudo-normals to define the tangent vectors.
+ * pseudo-normals to define the tangent vectors. Faces of two coplanar triangles
+ * will be marked as quads.
  *
  * @param minSharpAngle degrees, default 60. Any edges with angles greater than
  * this value will remain sharp. The rest will be smoothed to G1 continuity,
@@ -722,11 +724,12 @@ Manifold Manifold::SmoothOut(float minSharpAngle, float minSmoothness) const {
 
 /**
  * Increase the density of the mesh by splitting every edge into n pieces. For
- * instance, with n = 2, each triangle will be split into 4 triangles. These
- * will all be coplanar (and will not be immediately collapsed) unless the
- * Mesh/Manifold has halfedgeTangents specified (e.g. from the Smooth()
- * constructor), in which case the new vertices will be moved to the
- * interpolated surface according to their barycentric coordinates.
+ * instance, with n = 2, each triangle will be split into 4 triangles. Quads
+ * will ignore their interior triangle bisector. These will all be coplanar (and
+ * will not be immediately collapsed) unless the Mesh/Manifold has
+ * halfedgeTangents specified (e.g. from the Smooth() constructor), in which
+ * case the new vertices will be moved to the interpolated surface according to
+ * their barycentric coordinates.
  *
  * @param n The number of pieces to split every edge into. Must be > 1.
  */
@@ -743,7 +746,8 @@ Manifold Manifold::Refine(int n) const {
  * roughly the input length. Interior verts are added to keep the rest of the
  * triangulation edges also of roughly the same length. If halfedgeTangents are
  * present (e.g. from the Smooth() constructor), the new vertices will be moved
- * to the interpolated surface according to their barycentric coordinates.
+ * to the interpolated surface according to their barycentric coordinates. Quads
+ * will ignore their interior triangle bisector.
  *
  * @param length The length that edges will be broken down to.
  */

src/manifold/src/shared.h

@@ -40,16 +40,6 @@ inline int NextHalfedge(int current) {
   return current;
 }
 
-inline glm::vec3 UVW(int vert, const glm::vec3* barycentric) {
-  glm::vec3 uvw(0.0f);
-  if (vert < 0) {
-    uvw[vert + 3] = 1;
-  } else {
-    uvw = barycentric[vert];
-  }
-  return uvw;
-}
-
 inline glm::mat3 NormalTransform(const glm::mat4x3& transform) {
   return glm::inverse(glm::transpose(glm::mat3(transform)));
 }
@@ -143,7 +133,7 @@ struct Halfedge {
 
 struct Barycentric {
   int tri;
-  glm::vec3 uvw;
+  glm::vec4 uvw;
 };
 
 struct TriRef {