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- import igl
- V = igl.eigen.MatrixXd()
- F = igl.eigen.MatrixXi()
- # Load a mesh in OFF format
- igl.readOFF("../tutorial/shared/cheburashka.off", V, F)
- # Read scalar function values from a file, U: #V by 1
- U = igl.eigen.MatrixXd()
- igl.readDMAT("../tutorial/shared/cheburashka-scalar.dmat",U)
- U = U.col(0)
- # Compute gradient operator: #F*3 by #V
- G = igl.eigen.SparseMatrixd()
- igl.grad(V,F,G)
- # Compute gradient of U
- GU = (G*U).MapMatrix(F.rows(),3)
- # Compute gradient magnitude
- GU_mag = GU.rowwiseNorm()
- viewer = igl.viewer.Viewer()
- viewer.data.set_mesh(V, F)
- # Compute pseudocolor for original function
- C = igl.eigen.MatrixXd()
- igl.jet(U,True,C)
- # Or for gradient magnitude
- # igl.jet(GU_mag,True,C)
- viewer.data.set_colors(C);
- # Average edge length divided by average gradient (for scaling)
- max_size = igl.avg_edge_length(V,F) / GU_mag.mean()
- # Draw a black segment in direction of gradient at face barycenters
- BC = igl.eigen.MatrixXd()
- igl.barycenter(V,F,BC)
- black = igl.eigen.MatrixXd([[0.0,0.0,0.0]])
- viewer.data.add_edges(BC,BC+max_size*GU, black)
- # Hide wireframe
- viewer.core.show_lines = False
- viewer.launch()
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