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 <MRMeshC/MRBitSet.h>
  #include <MRMeshC/MRExpandShrink.h>
  #include <MRMeshC/MRLaplacian.h>
  #include <MRMeshC/MRMesh.h>
  #include <MRMeshC/MRMeshLoad.h>
  #include <MRMeshC/MRMeshSave.h>
   
  #include <stdlib.h>
   
  int main( int argc, char* argv[] )
  {
      // Load mesh
      MRMesh* mesh = mrMeshLoadFromAnySupportedFormat( "mesh.stl", NULL );
   
      // Construct deformer on the mesh vertices
      MRLaplacian* lDeformer = mrLaplacianNew( mesh );
   
      // Find an area for the deformation anchor points
      const MRVertBitSet* verts = mrMeshTopologyGetValidVerts( mrMeshTopology( mesh ) );
      MRVertId ancV0 = { mrBitSetFindFirst( (MRBitSet*)verts ) };
      MRVertId ancV1 = { mrBitSetFindLast( (MRBitSet*)verts ) };
      // Mark the anchor points in the free area
      MRVertBitSet* freeVerts = mrVertBitSetNew( mrBitSetSize( (MRBitSet*)verts ), false );
      mrBitSetSet( (MRBitSet*)verts, ancV0.id, true );
      mrBitSetSet( (MRBitSet*)verts, ancV1.id, true );
      // Expand the free area
      mrExpandVertRegion( mrMeshTopology( mesh ), freeVerts, 5 );
   
      // Initialize laplacian
      mrLaplacianInit( lDeformer, freeVerts, MREdgeWeightsCotan, MRVertexMassNeiArea, MRLaplacianRememberShapeYes );
   
      MRBox3f bbox = mrMeshComputeBoundingBox( mesh, NULL );
      float shiftAmount = mrBox3fDiagonal( &bbox ) * 0.01f;
      // Fix the anchor vertices in the required position
      const MRVector3f* points = mrMeshPoints( mesh );
      MRVector3f posV0 = mrMeshNormalFromVert( mesh, ancV0 );
      posV0 = mrVector3fMulScalar( &posV0, shiftAmount );
      posV0 = mrVector3fAdd( &points[ancV0.id], &posV0 );
      mrLaplacianFixVertex( lDeformer, ancV0, &posV0, true );
      MRVector3f posV1 = mrMeshNormalFromVert( mesh, ancV1 );
      posV1 = mrVector3fMulScalar( &posV1, shiftAmount );
      posV1 = mrVector3fAdd( &points[ancV1.id], &posV1 );
      mrLaplacianFixVertex( lDeformer, ancV1, &posV1, true );
   
      // Move the free vertices according to the anchor ones
      mrLaplacianApply( lDeformer );
   
      // Invalidate the mesh because of the external vertex changes
      mrMeshInvalidateCaches( mesh, true );
   
      // Save the deformed mesh
      mrMeshSaveToAnySupportedFormat( mesh, "deformed_mesh.stl", NULL, NULL );
   
      mrVertBitSetFree( freeVerts );
      mrLaplacianFree( lDeformer );
      mrMeshFree( mesh );
      return EXIT_SUCCESS;
  }