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- # Add the igl library to the modules search path
- import sys, os
- sys.path.insert(0, os.getcwd() + "/../")
- import pyigl as igl
- V = igl.eigen.MatrixXd()
- F = igl.eigen.MatrixXi()
- igl.readOFF("../../tutorial/shared/camelhead.off",V,F)
- # Find boundary edges
- E = igl.eigen.MatrixXi()
- igl.boundary_facets(F,E);
- # Find boundary vertices
- b = igl.eigen.MatrixXi()
- IA = igl.eigen.MatrixXi()
- IC = igl.eigen.MatrixXi()
- igl.unique(E,b,IA,IC);
- # List of all vertex indices
- vall = igl.eigen.MatrixXi()
- vin = igl.eigen.MatrixXi()
- igl.coloni(0,V.rows()-1,vall)
- # List of interior indices
- igl.setdiff(vall,b,vin,IA)
- # Construct and slice up Laplacian
- L = igl.eigen.SparseMatrixd()
- L_in_in = igl.eigen.SparseMatrixd()
- L_in_b = igl.eigen.SparseMatrixd()
- igl.cotmatrix(V,F,L)
- igl.slice(L,vin,vin,L_in_in)
- igl.slice(L,vin,b,L_in_b)
- # Dirichlet boundary conditions from z-coordinate
- bc = igl.eigen.MatrixXd()
- Z = V.col(2)
- igl.slice(Z,b,bc)
- # Solve PDE
- solver = igl.eigen.SimplicialLLTsparse(-L_in_in)
- Z_in = solver.solve(L_in_b*bc)
- # slice into solution
- igl.slice_into(Z_in,vin,Z)
- # Alternative, short hand
- mqwf = igl.min_quad_with_fixed_data()
- # Linear term is 0
- B = igl.eigen.MatrixXd()
- B.setZero(V.rows(),1);
- # Empty constraints
- Beq = igl.eigen.MatrixXd()
- Aeq = igl.eigen.SparseMatrixd()
- # Our cotmatrix is _negative_ definite, so flip sign
- igl.min_quad_with_fixed_precompute(-L,b,Aeq,True,mqwf)
- igl.min_quad_with_fixed_solve(mqwf,B,bc,Beq,Z)
- # Pseudo-color based on solution
- C = igl.eigen.MatrixXd()
- igl.jet(Z,True,C)
- # Plot the mesh with pseudocolors
- viewer = igl.viewer.Viewer()
- viewer.data.set_mesh(V, F)
- viewer.core.show_lines = False
- viewer.data.set_colors(C)
- viewer.launch()
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