HnMeshUtils: added GetTotalIndexCount function

Author: TheMostDiligent

Hydrogent/include/HnMeshUtils.hpp

@@ -28,6 +28,7 @@
 
 #include "pxr/imaging/hd/types.h"
 #include "pxr/imaging/hd/meshTopology.h"
+#include "FlagEnum.h"
 
 namespace Diligent
 {
@@ -65,6 +66,17 @@ class HnMeshUtils final
     size_t GetNumEdges(size_t* NumFaces = nullptr) const;
 
 
+    enum GET_TOTAL_INDEX_COUNT_FLAGS : uint32_t
+    {
+        GET_TOTAL_INDEX_COUNT_FLAG_NONE        = 0u,
+        GET_TOTAL_INDEX_COUNT_FLAG_TRIANGLES   = 1u << 0u,
+        GET_TOTAL_INDEX_COUNT_FLAG_EDGES_LIST  = 1u << 1u,
+        GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP = 1u << 2u,
+        GET_TOTAL_INDEX_COUNT_FLAG_POINTS      = 1u << 3u,
+    };
+    /// Returns the total number of indices (triangles + edges + points)
+    size_t GetTotalIndexCount(GET_TOTAL_INDEX_COUNT_FLAGS Flags) const;
+
     /// Triangulates the mesh and returns the triangle indices and the start of each subset.
     ///
     /// \param[in]  UseFaceVertexIndices - Whether to use face vertex indices.
@@ -207,6 +219,7 @@ class HnMeshUtils final
     const pxr::HdMeshTopology& m_Topology;
     const pxr::SdfPath&        m_MeshId;
 };
+DEFINE_FLAG_ENUM_OPERATORS(HnMeshUtils::GET_TOTAL_INDEX_COUNT_FLAGS);
 
 } // namespace USD
 

Hydrogent/src/HnMeshUtils.cpp

@@ -105,6 +105,7 @@ void HnMeshUtils::Triangulate(bool                UseFaceVertexIndices,
 
     // Count the number of triangles
     const size_t NumTriangles = GetNumTriangles();
+    VERIFY_EXPR(NumTriangles * 3 == GetTotalIndexCount(GET_TOTAL_INDEX_COUNT_FLAG_TRIANGLES));
 
     // Triangulate faces
     TriangleIndices.reserve(NumTriangles);
@@ -296,6 +297,7 @@ pxr::VtIntArray HnMeshUtils::ComputeEdgeIndices(bool UseFaceVertexIndices, bool
             });
         VERIFY_EXPR(EdgeIndices.size() == NumEdges * 2);
     }
+    VERIFY_EXPR(EdgeIndices.size() == GetTotalIndexCount(UseLineStrip ? GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP : GET_TOTAL_INDEX_COUNT_FLAG_EDGES_LIST));
 
     if (UseFaceVertexIndices)
     {
@@ -352,10 +354,38 @@ pxr::VtIntArray HnMeshUtils::ComputePointIndices(bool ConvertToFaceVarying) cons
         for (int i = 0; i < NumPoints; ++i)
             PointIndices[i] = i;
     }
+    VERIFY_EXPR(PointIndices.size() == GetTotalIndexCount(GET_TOTAL_INDEX_COUNT_FLAG_POINTS));
 
     return PointIndices;
 }
 
+size_t HnMeshUtils::GetTotalIndexCount(GET_TOTAL_INDEX_COUNT_FLAGS Flags) const
+{
+    VERIFY((Flags & (GET_TOTAL_INDEX_COUNT_FLAG_EDGES_LIST | GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP)) != (GET_TOTAL_INDEX_COUNT_FLAG_EDGES_LIST | GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP),
+           "COUNT_EDGES_LIST and COUNT_EDGES_STRIP flags are mutually exclusive");
+
+    size_t NumIndices = 0;
+    if (Flags & GET_TOTAL_INDEX_COUNT_FLAG_TRIANGLES)
+    {
+        size_t NumTriangles = GetNumTriangles();
+        NumIndices += NumTriangles * 3;
+    }
+
+    if (Flags & (GET_TOTAL_INDEX_COUNT_FLAG_EDGES_LIST | GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP))
+    {
+        size_t NumFaces = 0;
+        size_t NumEdges = GetNumEdges(&NumFaces);
+        NumIndices += (Flags & GET_TOTAL_INDEX_COUNT_FLAG_EDGES_STRIP) ? NumEdges + NumFaces * 2 : NumEdges * 2;
+    }
+
+    if (Flags & GET_TOTAL_INDEX_COUNT_FLAG_POINTS)
+    {
+        NumIndices += m_Topology.GetNumPoints();
+    }
+
+    return NumIndices;
+}
+
 template <typename T>
 pxr::VtValue ConvertVertexArrayToFaceVaryingArray(const pxr::VtIntArray& FaceVertexIndices, const pxr::VtArray<T>& VertexArray, size_t ValuesPerVertex)
 {