Add new function in MeshManager to merge all submeshes of a mesh into one (#588)

---------

Signed-off-by: Ian Chen <[email protected]>

Author: iche033

graphics/include/gz/common/MeshManager.hh

@@ -290,11 +290,17 @@ namespace gz
       /// \param[in] _voxelResolution Voxel resolution to use. Higher value
       /// produces more accurate shapes.
       /// \return A vector of decomposed submeshes.
-      public: std::vector<SubMesh> ConvexDecomposition(
+      public: static std::vector<SubMesh> ConvexDecomposition(
                   const common::SubMesh &_subMesh,
                   std::size_t _maxConvexHulls = 16u,
                   std::size_t _voxelResolution = 200000u);
 
+      /// \brief Merge all submeshes from one mesh into one single submesh.
+      /// \param[in] _mesh Input mesh with submeshes to merge.
+      /// \return A new mesh with the submeshes merged.
+      public: static std::unique_ptr<Mesh> MergeSubMeshes(
+                  const common::Mesh &_mesh);
+
       /// \brief Converts a vector of polylines into a table of vertices and
       /// a list of edges (each made of 2 points from the table of vertices.
       /// \param[in] _polys the polylines

graphics/src/ColladaLoader_TEST.cc

@@ -242,8 +242,6 @@ TEST_F(ColladaLoader, TexCoordSets)
   EXPECT_EQ(math::Vector2d(0, 1), subMeshB->TexCoordBySet(0u, 0u));
   EXPECT_EQ(math::Vector2d(0, 1), subMeshB->TexCoordBySet(1u, 0u));
   EXPECT_EQ(math::Vector2d(0, 1), subMeshB->TexCoordBySet(2u, 0u));
-  EXPECT_EQ(math::Vector2d(0, 1), subMeshB->TexCoordBySet(1u, 0u));
-  EXPECT_EQ(math::Vector2d(0, 1), subMeshB->TexCoordBySet(2u, 0u));
 
   EXPECT_TRUE(subMeshB->HasTexCoordBySet(0u, 0u));
   EXPECT_TRUE(subMeshB->HasTexCoordBySet(1u, 0u));

graphics/src/MeshManager.cc

@@ -19,6 +19,7 @@
 
 #include <cctype>
 #include <cstdint>
+#include <memory>
 #include <mutex>
 #include <string>
 #include <unordered_map>
@@ -1760,3 +1761,72 @@ MeshManager::ConvexDecomposition(const SubMesh &_subMesh,
 
   return decomposed;
 }
+
+//////////////////////////////////////////////////
+std::unique_ptr<Mesh> MeshManager::MergeSubMeshes(const Mesh &_mesh)
+{
+  SubMesh mergedSubMesh;
+
+  // The final merged submesh should contain all the texcoord sets
+  // in the original submeshes. Determine the max texcoord sets we need.
+  unsigned int maxTexCoordSet = 0u;
+  for (unsigned int i = 0u; i < _mesh.SubMeshCount(); ++i)
+  {
+    auto submesh = _mesh.SubMeshByIndex(i).lock();
+    maxTexCoordSet = (maxTexCoordSet > submesh->TexCoordSetCount()) ?
+        maxTexCoordSet : submesh->TexCoordSetCount();
+  }
+
+  unsigned int indexOffset = 0u;
+  for (unsigned int i = 0u; i < _mesh.SubMeshCount(); ++i)
+  {
+    auto submesh = _mesh.SubMeshByIndex(i).lock();
+    // vertices
+    for (unsigned int j = 0; j < submesh->VertexCount(); ++j)
+    {
+      mergedSubMesh.AddVertex(submesh->Vertex(j));
+    }
+
+    // normals
+    for (unsigned int j = 0; j < submesh->NormalCount(); ++j)
+    {
+      mergedSubMesh.AddNormal(submesh->Normal(j));
+    }
+
+    // indices - the index needs to start at an offset for each new submesh
+    for (unsigned int j = 0; j < submesh->IndexCount(); ++j)
+    {
+      mergedSubMesh.AddIndex(submesh->Index(j) + indexOffset);
+    }
+    indexOffset += submesh->VertexCount();
+
+    // texcoords
+    for (unsigned int j = 0; j < maxTexCoordSet; ++j)
+    {
+      if (j < submesh->TexCoordSetCount())
+      {
+        // Populate texcoords from input submesh
+        for (unsigned int k = 0; k < submesh->TexCoordCountBySet(j); ++k)
+        {
+          mergedSubMesh.AddTexCoordBySet(submesh->TexCoordBySet(k, j), j);
+        }
+      }
+      else
+      {
+        // Set texcoord to zero if the input submesh does not have that many
+        // texcoord sets. Note the texcoord count should be the same as vertex
+        // count.
+        for (unsigned int k = 0; k < submesh->VertexCount(); ++k)
+        {
+          mergedSubMesh.AddTexCoordBySet(math::Vector2d::Zero, j);
+        }
+      }
+    }
+  }
+  auto mesh = std::make_unique<Mesh>();
+  mesh->SetName(_mesh.Name() + "_merged");
+  mergedSubMesh.SetName(mesh->Name() + "_submesh");
+  mesh->AddSubMesh(mergedSubMesh);
+
+  return mesh;
+}

graphics/src/MeshManager_TEST.cc

@@ -304,7 +304,7 @@ TEST_F(MeshManager, ConvexDecomposition)
   std::size_t maxConvexHulls = 4;
   std::size_t resolution = 1000;
   auto submesh = boxMesh->SubMeshByIndex(0u).lock();
-  auto decomposed = std::move(mgr->ConvexDecomposition(
+  auto decomposed = std::move(common::MeshManager::ConvexDecomposition(
       *(submesh.get()), maxConvexHulls, resolution));
 
   // Decomposing a box should just produce a box
@@ -321,7 +321,7 @@ TEST_F(MeshManager, ConvexDecomposition)
   ASSERT_NE(nullptr, drillMesh);
   EXPECT_EQ(1u, drillMesh->SubMeshCount());
   submesh = drillMesh->SubMeshByIndex(0u).lock();
-  decomposed = std::move(mgr->ConvexDecomposition(
+  decomposed = std::move(common::MeshManager::ConvexDecomposition(
       *(submesh.get()), maxConvexHulls, resolution));
 
   // A drill should be decomposed into multiple submeshes
@@ -337,4 +337,93 @@ TEST_F(MeshManager, ConvexDecomposition)
   }
 }
 
+/////////////////////////////////////////////////
+TEST_F(MeshManager, MergeSubMeshes)
+{
+  auto mgr = common::MeshManager::Instance();
+  const common::Mesh *mesh = mgr->Load(
+      common::testing::TestFile("data",
+        "multiple_texture_coordinates_triangle.dae"));
+  ASSERT_NE(nullptr, mesh);
+  EXPECT_EQ(2u, mesh->SubMeshCount());
+  auto submesh = mesh->SubMeshByIndex(0u).lock();
+  ASSERT_NE(nullptr, submesh);
+  EXPECT_EQ(3u, submesh->VertexCount());
+  EXPECT_EQ(3u, submesh->NormalCount());
+  EXPECT_EQ(3u, submesh->IndexCount());
+  EXPECT_EQ(2u, submesh->TexCoordSetCount());
+  EXPECT_EQ(3u, submesh->TexCoordCountBySet(0));
+  EXPECT_EQ(3u, submesh->TexCoordCountBySet(1));
+  auto submeshB = mesh->SubMeshByIndex(1u).lock();
+  ASSERT_NE(nullptr, submeshB);
+  EXPECT_EQ(3u, submeshB->VertexCount());
+  EXPECT_EQ(3u, submeshB->NormalCount());
+  EXPECT_EQ(3u, submeshB->IndexCount());
+  EXPECT_EQ(3u, submeshB->TexCoordSetCount());
+  EXPECT_EQ(3u, submeshB->TexCoordCountBySet(0));
+  EXPECT_EQ(3u, submeshB->TexCoordCountBySet(1));
+  EXPECT_EQ(3u, submeshB->TexCoordCountBySet(2));
+
+  // merge all submeshes into one
+  auto merged = common::MeshManager::MergeSubMeshes(*mesh);
+  ASSERT_NE(nullptr, merged);
+  EXPECT_FALSE(merged->Name().empty());
+  EXPECT_EQ(1u, merged->SubMeshCount());
+  auto mergedSubmesh = merged->SubMeshByIndex(0u).lock();
+  ASSERT_NE(nullptr, mergedSubmesh);
+  EXPECT_FALSE(mergedSubmesh->Name().empty());
+
+  // Verify vertice, normals, indice, and texcoord values in the
+  // final merged submesh
+  EXPECT_EQ(6u, mergedSubmesh->VertexCount());
+  EXPECT_EQ(6u, mergedSubmesh->NormalCount());
+  EXPECT_EQ(6u, mergedSubmesh->IndexCount());
+  EXPECT_EQ(3u, mergedSubmesh->TexCoordSetCount());
+  EXPECT_EQ(6u, mergedSubmesh->TexCoordCountBySet(0));
+  EXPECT_EQ(6u, mergedSubmesh->TexCoordCountBySet(1));
+  EXPECT_EQ(6u, mergedSubmesh->TexCoordCountBySet(2));
+
+  EXPECT_EQ(math::Vector3d(0, 0, 0), mergedSubmesh->Vertex(0u));
+  EXPECT_EQ(math::Vector3d(10, 0, 0), mergedSubmesh->Vertex(1u));
+  EXPECT_EQ(math::Vector3d(10, 10, 0), mergedSubmesh->Vertex(2u));
+  EXPECT_EQ(math::Vector3d(10, 0, 0), mergedSubmesh->Vertex(3u));
+  EXPECT_EQ(math::Vector3d(20, 0, 0), mergedSubmesh->Vertex(4u));
+  EXPECT_EQ(math::Vector3d(20, 10, 0), mergedSubmesh->Vertex(5u));
+
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(0u));
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(1u));
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(2u));
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(3u));
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(4u));
+  EXPECT_EQ(math::Vector3d(0, 0, 1), mergedSubmesh->Normal(5u));
+
+  EXPECT_EQ(0u, mergedSubmesh->Index(0u));
+  EXPECT_EQ(1u, mergedSubmesh->Index(1u));
+  EXPECT_EQ(2u, mergedSubmesh->Index(2u));
+  EXPECT_EQ(3u, mergedSubmesh->Index(3u));
+  EXPECT_EQ(4u, mergedSubmesh->Index(4u));
+  EXPECT_EQ(5u, mergedSubmesh->Index(5u));
+
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(0u, 0u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(1u, 0u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(2u, 0u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(3u, 0u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(4u, 0u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(5u, 0u));
+
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(0u, 1u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(1u, 1u));
+  EXPECT_EQ(math::Vector2d(0, 1), mergedSubmesh->TexCoordBySet(2u, 1u));
+  EXPECT_EQ(math::Vector2d(0, 0.5), mergedSubmesh->TexCoordBySet(3u, 1u));
+  EXPECT_EQ(math::Vector2d(0, 0.4), mergedSubmesh->TexCoordBySet(4u, 1u));
+  EXPECT_EQ(math::Vector2d(0, 0.3), mergedSubmesh->TexCoordBySet(5u, 1u));
+
+  EXPECT_EQ(math::Vector2d(0, 0), mergedSubmesh->TexCoordBySet(0u, 2u));
+  EXPECT_EQ(math::Vector2d(0, 0), mergedSubmesh->TexCoordBySet(1u, 2u));
+  EXPECT_EQ(math::Vector2d(0, 0), mergedSubmesh->TexCoordBySet(2u, 2u));
+  EXPECT_EQ(math::Vector2d(0, 0.8), mergedSubmesh->TexCoordBySet(3u, 2u));
+  EXPECT_EQ(math::Vector2d(0, 0.7), mergedSubmesh->TexCoordBySet(4u, 2u));
+  EXPECT_EQ(math::Vector2d(0, 0.6), mergedSubmesh->TexCoordBySet(5u, 2u));
+}
+
 #endif