def compas_mesh_to_occ_shell(mesh: Mesh) -> TopoDS_Shell: """Convert a general COMPAS mesh to an OCC shell. Parameters ---------- mesh : :class:`~compas.datastructures.Mesh` A COMPAS mesh data structure. Returns ------- TopoDS_Shell """ # https://github.com/tpaviot/pythonocc-demos/blob/master/examples/core_geometry_geomplate.py shell = TopoDS_Shell() builder = BRep_Builder() builder.MakeShell(shell) for face in mesh.faces(): points = mesh.face_coordinates(face) if len(points) == 3: builder.Add(shell, triangle_to_face(points)) elif len(points) == 4: builder.Add(shell, quad_to_face(points)) else: builder.Add(shell, ngon_to_face(points)) return shell
def compas_quadmesh_to_occ_shell(mesh: Mesh) -> TopoDS_Shell: """Convert a COMPAS quad mesh to an OCC shell. Parameters ---------- mesh : :class:`~compas.datastructures.Mesh` A COMPAS mesh data structure with quad faces. Returns ------- TopoDS_Shell Raises ------ AssertionError If the input mesh is not a quad mesh. """ assert mesh.is_quadmesh(), "The input mesh is not a quad mesh." shell = TopoDS_Shell() builder = BRep_Builder() builder.MakeShell(shell) for face in mesh.faces(): points = mesh.face_coordinates(face) builder.Add(shell, quad_to_face(points)) return shell
def delaunay_from_points(points, boundary=None, holes=None, tiny=1e-12): """Computes the delaunay triangulation for a list of points. Parameters ---------- points : sequence of tuple XYZ coordinates of the original points. boundary : sequence of tuples list of ordered points describing the outer boundary (optional) holes : list of sequences of tuples list of polygons (ordered points describing internal holes (optional) Returns ------- list The faces of the triangulation. Each face is a triplet of indices referring to the list of point coordinates. Notes ----- For more info, see [1]_. References ---------- .. [1] Sloan, S. W., 1987 *A fast algorithm for constructing Delaunay triangulations in the plane* Advances in Engineering Software 9(1): 34-55, 1978. Example ------- .. plot:: :include-source: from compas.datastructures import Mesh from compas.geometry import pointcloud_xy from compas.geometry import delaunay_from_points from compas_plotters import MeshPlotter points = pointcloud_xy(20, (0, 50)) faces = delaunay_from_points(points) delaunay = Mesh.from_vertices_and_faces(points, faces) plotter = MeshPlotter(delaunay) plotter.draw_vertices(radius=0.1) plotter.draw_faces() plotter.show() """ from compas.datastructures import Mesh from compas.datastructures import trimesh_swap_edge def super_triangle(coords, ccw=True): centpt = centroid_points(coords) bbpts = bounding_box(coords) dis = distance_point_point(bbpts[0], bbpts[2]) dis = dis * 300 v1 = (0 * dis, 2 * dis, 0) v2 = (1.73205 * dis, -1.0000000000001 * dis, 0 ) # due to numerical issues v3 = (-1.73205 * dis, -1 * dis, 0) pt1 = add_vectors(centpt, v1) pt2 = add_vectors(centpt, v2) pt3 = add_vectors(centpt, v3) if ccw: return pt1, pt3, pt2 return pt1, pt2, pt3 mesh = Mesh() # to avoid numerical issues for perfectly structured point sets points = [(point[0] + random.uniform(-tiny, tiny), point[1] + random.uniform(-tiny, tiny), 0.0) for point in points] # create super triangle pt1, pt2, pt3 = super_triangle(points) # add super triangle vertices to mesh n = len(points) super_keys = n, n + 1, n + 2 mesh.add_vertex(super_keys[0], {'x': pt1[0], 'y': pt1[1], 'z': pt1[2]}) mesh.add_vertex(super_keys[1], {'x': pt2[0], 'y': pt2[1], 'z': pt2[2]}) mesh.add_vertex(super_keys[2], {'x': pt3[0], 'y': pt3[1], 'z': pt3[2]}) mesh.add_face(super_keys) # iterate over points for key, point in enumerate(points): # newtris should be intialised here # check in which triangle this point falls for fkey in list(mesh.faces()): abc = mesh.face_coordinates(fkey) if is_point_in_triangle_xy(point, abc, True): # generate 3 new triangles (faces) and delete surrounding triangle key, newtris = mesh.insert_vertex(fkey, key=key, xyz=point, return_fkeys=True) break while newtris: fkey = newtris.pop() face = mesh.face_vertices(fkey) i = face.index(key) u = face[i - 2] v = face[i - 1] nbr = mesh.halfedge[v][u] if nbr is not None: a, b, c = mesh.face_coordinates(nbr) circle = circle_from_points_xy(a, b, c) if is_point_in_circle_xy(point, circle): fkey, nbr = trimesh_swap_edge(mesh, u, v) newtris.append(fkey) newtris.append(nbr) # Delete faces adjacent to supertriangle for key in super_keys: mesh.delete_vertex(key) # Delete faces outside of boundary if boundary: for fkey in list(mesh.faces()): centroid = mesh.face_centroid(fkey) if not is_point_in_polygon_xy(centroid, boundary): mesh.delete_face(fkey) # Delete faces inside of inside boundaries if holes: for polygon in holes: for fkey in list(mesh.faces()): centroid = mesh.face_centroid(fkey) if is_point_in_polygon_xy(centroid, polygon): mesh.delete_face(fkey) return [mesh.face_vertices(fkey) for fkey in mesh.faces()]