Export of points and triangles from mesh (#131)

Author: Fedr

doxygen/HowToExamples.dox

@@ -52,6 +52,21 @@ mesh.transform( rotationXf );
 \sa \ref MR::subdivideMesh
 \sa \ref MR::Mesh
 
+Export example of points and triangles from mesh (e.g. for rendering)
+
+\code
+// create some mesh
+Mesh mesh = makeCube();
+
+// all vertices of valid triangles
+const std::vector<std::array<VertId, 3>> triangles = mesh.topology.getAllTriVerts();
+
+// all point coordinates
+const std::vector<Vector3f> & points =  mesh.points.vec_;
+// triangle vertices as tripples of ints (pointing to elements in points vector)
+const int * vertexTripples = reinterpret_cast<const int*>( triangles.data() );
+\endcode
+
 \section PythonCodeExamples Python Basic Examples
 
 In this section we provide the same examples but with python code\n

source/MRMesh/MRMesh.cpp

@@ -14,6 +14,8 @@
 #include "MRLineSegm.h"
 #include "MRConstants.h"
 #include "MRComputeBoundingBox.h"
+#include "MRGTest.h"
+#include "MRCube.h"
 #include "MRPch/MRTBB.h"
 
 namespace
@@ -776,4 +778,17 @@ Vector3f Mesh::findCenterFromBBox() const
     return computeBoundingBox().center();
 }
 
+TEST( MRMesh, BasicExport )
+{
+    Mesh mesh = makeCube();
+
+    const std::vector<std::array<VertId, 3>> triangles = mesh.topology.getAllTriVerts();
+
+    const std::vector<Vector3f> & points =  mesh.points.vec_;
+    const int * vertexTripples = reinterpret_cast<const int*>( triangles.data() );
+
+    (void)points;
+    (void)vertexTripples;
+}
+
 } //namespace MR

source/MRMesh/MRMeshTopology.cpp

@@ -195,6 +195,21 @@ void MeshTopology::getLeftTriVerts( EdgeId a, VertId & v0, VertId & v1, VertId &
     assert( a == prev( c.sym() ) );
 }
 
+std::vector<std::array<VertId, 3>> MeshTopology::getAllTriVerts() const
+{
+    MR_TIMER
+    std::vector<std::array<VertId, 3>> res;
+    res.reserve( numValidFaces_ );
+    for ( auto f : validFaces_ )
+    {
+        VertId vs[3];
+        getTriVerts( f, vs );
+        res.push_back( { vs[0], vs[1], vs[2] } );
+    }
+
+    return res;
+}
+
 bool MeshTopology::isLeftQuad( EdgeId a ) const
 {
     assert( a.valid() );

source/MRMesh/MRMeshTopology.h

@@ -72,6 +72,8 @@ class MeshTopology
     // the vertices are returned in counter-clockwise order if look from mesh outside
     void getTriVerts( FaceId f, VertId & v0, VertId & v1, VertId & v2 ) const { getLeftTriVerts( edgeWithLeft( f ), v0, v1, v2 ); }
     void getTriVerts( FaceId f, VertId (&v)[3] ) const { getTriVerts( f, v[0], v[1], v[2] ); }
+    // returns all valid triangle vertices
+    [[nodiscard]] MRMESH_API std::vector<std::array<VertId, 3>> getAllTriVerts() const;
     // gets 3 vertices of the left face ( face-id may not exist, but the shape must be triangular)
     // the vertices are returned in counter-clockwise order if look from mesh outside
     MRMESH_API void getLeftTriVerts( EdgeId a, VertId & v0, VertId & v1, VertId & v2 ) const;