Laplacian deformation Example

Example of using Laplacian deformer

• C++

  #include <MRMesh/MRBox.h>
  #include <MRMesh/MRExpandShrink.h>
  #include <MRMesh/MRLaplacian.h>
  #include <MRMesh/MRMesh.h>
  #include <MRMesh/MRMeshLoad.h>
  #include <MRMesh/MRMeshSave.h>
   
  #include <iostream>
   
  int main()
  {
      // Load mesh
      auto loadRes = MR::MeshLoad::fromAnySupportedFormat( "mesh.stl" );
      if ( !loadRes.has_value() )
      {
          std::cerr << loadRes.error() << std::endl;
          return 1;
      }
      MR::Mesh& mesh = *loadRes;
   
      // Construct deformer on the mesh vertices
      MR::Laplacian lDeformer( mesh );
   
      // Find an area for the deformation anchor points
      const auto ancV0 = mesh.topology.getValidVerts().find_first();
      const auto ancV1 = mesh.topology.getValidVerts().find_last();
      // Mark the anchor points in the free area
      MR::VertBitSet freeVerts;
      freeVerts.resize( mesh.topology.getValidVerts().size() );
      freeVerts.set( ancV0, true );
      freeVerts.set( ancV1, true );
      // Expand the free area
      MR::expand( mesh.topology, freeVerts, 5 );
   
      // Initialize laplacian
      lDeformer.init( freeVerts, MR::EdgeWeights::Cotan, MR::VertexMass::NeiArea );
   
      const auto shiftAmount = mesh.computeBoundingBox().diagonal() * 0.01f;
      // Fix the anchor vertices in the required position
      lDeformer.fixVertex( ancV0, mesh.points[ancV0] + mesh.normal( ancV0 ) * shiftAmount );
      lDeformer.fixVertex( ancV1, mesh.points[ancV1] + mesh.normal( ancV1 ) * shiftAmount );
   
      // Move the free vertices according to the anchor ones
      lDeformer.apply();
   
      // Invalidate the mesh because of the external vertex changes
      mesh.invalidateCaches();
   
      // Save the deformed mesh
      if ( auto saveRes = MR::MeshSave::toAnySupportedFormat( mesh, "deformed_mesh.stl" ); !saveRes )
      {
          std::cerr << saveRes.error() << std::endl;
          return 1;
      }
  }

• Python

  Note

  Python API version 3 and later

  from meshlib import mrmeshpy as mm
   
  # Load mesh
  mesh = mm.loadMesh("mesh.stl")
   
  # Construct deformer on mesh vertices
  lDeformer = mm.Laplacian(mesh)
   
  # Find area for deformation anchor points
  ancV0 = mesh.topology.getValidVerts().find_first()
  ancV1 = mesh.topology.getValidVerts().find_last()
  # Mark anchor points in free area
  freeVerts = mm.VertBitSet()
  freeVerts.resize(mesh.topology.getValidVerts().size())
  freeVerts.set( ancV0, True )
  freeVerts.set( ancV1, True )
  # Expand free area
  mm.expand(mesh.topology,freeVerts,5)
   
  # Initialize laplacian
  lDeformer.init(freeVerts,mm.EdgeWeights.Cotan,mm.VertexMass.NeiArea)
   
  shiftAmount = mesh.computeBoundingBox().diagonal()*0.01
  # Fix anchor vertices in required position
  lDeformer.fixVertex( ancV0, mesh.points.vec[ancV0.get()] + mesh.normal(ancV0) * shiftAmount )
  lDeformer.fixVertex( ancV1, mesh.points.vec[ancV1.get()] + mesh.normal(ancV1) * shiftAmount )
   
  # Move free vertices according to anchor ones
  lDeformer.apply()
   
  # Invalidate mesh because of external vertices changes
  mesh.invalidateCaches()
   
  # Save deformed mesh
  mm.saveMesh(mesh,"deformed_mesh.stl")

• C

  #include <MRCMesh/MRBitSet.h>
  #include <MRCMesh/MRExpandShrink.h>
  #include <MRCMesh/MRLaplacian.h>
  #include <MRCMesh/MRMesh.h>
  #include <MRCMesh/MRMeshLoad.h>
  #include <MRCMesh/MRMeshSave.h>
  #include <MRCMesh/MRMeshTopology.h>
  #include <MRCMesh/MRVector.h>
  #include <MRCMisc/expected_MR_Mesh_std_string.h>
  #include <MRCMisc/std_string.h>
   
  #include <stdio.h>
  #include <stdlib.h>
   
  int main( void )
  {
      // Load mesh
      MR_expected_MR_Mesh_std_string* meshEx = MR_MeshLoad_fromAnySupportedFormat_2( "mesh.stl", NULL, NULL );
      MR_Mesh* mesh = MR_expected_MR_Mesh_std_string_GetMutableValue( meshEx );
   
      // Handle failure to load mesh
      if ( !mesh )
      {
          fprintf( stderr, "Failed to load mesh: %s\n", MR_std_string_Data( MR_expected_MR_Mesh_std_string_GetError( meshEx ) ) );
          MR_expected_MR_Mesh_std_string_Destroy( meshEx );
          return 1;
      }
   
      // Construct deformer on the mesh vertices
      MR_Laplacian* lDeformer = MR_Laplacian_Construct_1( mesh );
   
      // Find an area for the deformation anchor points
      const MR_VertBitSet* verts = MR_MeshTopology_getValidVerts( MR_Mesh_Get_topology( mesh ) );
      MR_VertId ancV0 = MR_VertBitSet_find_first( verts );
      MR_VertId ancV1 = MR_VertBitSet_find_last( verts );
      // Mark the anchor points in the free area
      MR_VertBitSet* freeVerts = MR_VertBitSet_DefaultConstruct();
      MR_BitSet_resize( MR_VertBitSet_MutableUpcastTo_MR_BitSet( freeVerts ), MR_BitSet_size( MR_VertBitSet_UpcastTo_MR_BitSet( verts ) ), NULL );
   
      MR_BitSet_set_2( MR_VertBitSet_MutableUpcastTo_MR_BitSet( freeVerts ), ancV0.id_, true );
      MR_BitSet_set_2( MR_VertBitSet_MutableUpcastTo_MR_BitSet( freeVerts ), ancV1.id_, true );
      // Expand the free area
      MR_expand_MR_VertBitSet( MR_Mesh_Get_topology( mesh ), freeVerts, &(int32_t){5} );
   
      // Initialize laplacian
      MR_Laplacian_init( lDeformer, freeVerts, MR_EdgeWeights_Cotan, &(MR_VertexMass){MR_VertexMass_NeiArea}, NULL );
   
      MR_Box3f bbox = MR_Mesh_computeBoundingBox_1( mesh, NULL );
      float shiftAmount = MR_Box3f_diagonal( &bbox ) * 0.01f;
      // Fix the anchor vertices in the required position
      const MR_VertCoords* points = MR_Mesh_Get_points( mesh );
      MR_Vector3f posV0 = MR_Mesh_normal_MR_VertId( mesh, ancV0 );
      posV0 = MR_mul_MR_Vector3f_float( &posV0, shiftAmount );
      posV0 = MR_add_MR_Vector3f( MR_VertCoords_index_const( points, ancV0 ), &posV0 );
      MR_Laplacian_fixVertex_3( lDeformer, ancV0, &posV0, NULL );
      MR_Vector3f posV1 = MR_Mesh_normal_MR_VertId( mesh, ancV1 );
      posV1 = MR_mul_MR_Vector3f_float( &posV1, shiftAmount );
      posV1 = MR_add_MR_Vector3f( MR_VertCoords_index_const( points, ancV1 ), &posV1 );
      MR_Laplacian_fixVertex_3( lDeformer, ancV1, &posV1, NULL );
   
      // Move the free vertices according to the anchor ones
      MR_Laplacian_apply( lDeformer );
   
      // Invalidate the mesh because of the external vertex changes
      MR_Mesh_invalidateCaches( mesh, NULL );
   
      // Save the deformed mesh
      MR_MeshSave_toAnySupportedFormat_3( mesh, "deformed_mesh.stl", NULL, NULL );
   
      MR_VertBitSet_Destroy( freeVerts );
      MR_Laplacian_Destroy( lDeformer );
      MR_expected_MR_Mesh_std_string_Destroy( meshEx );
      return EXIT_SUCCESS;
  }