Added tutorial 702

python/tutorial/702_WindingNumber.py

@@ -0,0 +1,112 @@
+import sys, os
+
+# Add the igl library to the modules search path
+sys.path.insert(0, os.getcwd() + "/../")
+import pyigl as igl
+
+from shared import TUTORIAL_SHARED_PATH, check_dependencies, print_usage
+
+dependencies = []
+check_dependencies(dependencies)
+
+
+def append_mesh(C_vis, F_vis, V_vis, V, F, color):
+    F_vis.conservativeResize(F_vis.rows() + F.rows(), 3)
+    F_vis.setBottomRows(F.rows(), F + V_vis.rows())
+    V_vis.conservativeResize(V_vis.rows() + V.rows(), 3)
+    V_vis.setBottomRows(V.rows(), V)
+    C_vis.conservativeResize(C_vis.rows() + F.rows(), 3)
+    colorM = igl.eigen.MatrixXd(F.rows(), C_vis.cols())
+    colorM.rowwiseSet(color)
+    C_vis.setBottomRows(F.rows(), colorM)
+
+
+def update(viewer):
+    global V, F, T, W, slice_z, overlay
+    plane = igl.eigen.MatrixXd([0, 0, 1, -((1 - slice_z) * V.col(2).minCoeff() + slice_z * V.col(2).maxCoeff())])
+    V_vis = igl.eigen.MatrixXd()
+    F_vis = igl.eigen.MatrixXi()
+    J = igl.eigen.MatrixXi()
+    bary = igl.eigen.SparseMatrixd()
+    igl.slice_tets(V, T, plane, V_vis, F_vis, J, bary)
+    W_vis = igl.eigen.MatrixXd()
+    igl.slice(W, J, W_vis)
+    C_vis = igl.eigen.MatrixXd()
+    igl.parula(W_vis, False, C_vis)
+
+    if overlay == 1:  # OVERLAY_INPUT
+        append_mesh(C_vis, F_vis, V_vis, V, F, igl.eigen.MatrixXd([[1., 0.894, 0.227]]))
+    elif overlay == 2:  # OVERLAY_OUTPUT
+        append_mesh(C_vis, F_vis, V_vis, V, F, igl.eigen.MatrixXd([[0.8, 0.8, 0.8]]))
+
+    viewer.data.clear()
+    viewer.data.set_mesh(V_vis, F_vis)
+    viewer.data.set_colors(C_vis)
+    viewer.data.set_face_based(True)
+
+
+def key_down(viewer, key, modifier):
+    global overlay, slice_z
+
+    if key == ord(' '):
+        overlay = (overlay + 1) % 3
+    elif key == ord('.'):
+        slice_z = min(slice_z + 0.01, 0.99)
+    elif key == ord(','):
+        slice_z = max(slice_z - 0.01, 0.01)
+
+    update(viewer)
+
+    return False
+
+
+if __name__ == "__main__":
+    keys = {"space": "toggle showing input mesh, output mesh or slice through tet-mesh of convex hull",
+            ". / ,": "push back/pull forward slicing plane"}
+
+    print_usage(keys)
+
+    V = igl.eigen.MatrixXd()
+    BC = igl.eigen.MatrixXd()
+    W = igl.eigen.MatrixXd()
+    T = igl.eigen.MatrixXi()
+    F = igl.eigen.MatrixXi()
+    G = igl.eigen.MatrixXi()
+
+    slice_z = 0.5
+    overlay = 0
+
+    # Load mesh: (V,T) tet-mesh of convex hull, F contains facets of input
+    # surface mesh _after_ self-intersection resolution
+    igl.readMESH(TUTORIAL_SHARED_PATH + "big-sigcat.mesh", V, T, F)
+
+    # Compute barycenters of all tets
+    igl.barycenter(V, T, BC)
+
+    # Compute generalized winding number at all barycenters
+    print("Computing winding number over all %i tets..." % T.rows())
+    igl.winding_number(V, F, BC, W)
+
+    # Extract interior tets
+    Wt = sum(W > 0.5)
+    CT = igl.eigen.MatrixXi(Wt, 4)
+    k = 0
+    for t in range(T.rows()):
+        if W[t] > 0.5:
+            CT.setRow(k, T.row(t))
+            k += 1
+
+    # find bounary facets of interior tets
+    igl.boundary_facets(CT, G)
+
+    # boundary_facets seem to be reversed...
+    G = G.rowwiseReverse()
+
+    # normalize
+    W = (W - W.minCoeff()) / (W.maxCoeff() - W.minCoeff())
+
+    # Plot the generated mesh
+    viewer = igl.viewer.Viewer()
+    update(viewer)
+    viewer.callback_key_down = key_down
+    viewer.launch()

python/tutorial/shared.py

@@ -14,3 +14,9 @@ def check_dependencies(deps):
 
     if not all_available:
         sys.exit(-1)
+
+
+def print_usage(key_dict):
+    print("Usage:")
+    for k in key_dict.keys():
+        print("%s : %s" %(k, key_dict[k]))