Sort list of points derived from Solid3d clockwise with Python

Civil3D
1

Hello all,

I’m trying to create a Point3dCollection of the bottom vertices of a Solid3d. However, when I run this script:

      for id in boundary_id:				
             obj = t.GetObject(id, OpenMode.ForRead)
					#find half of the vertices of a solid
					if isinstance(obj, Solid3d):
						brep = Brep(obj)
						vertices = brep.Vertices
						points_XYZ = []
						for i in vertices:
							point_vertice = i.Point
							points_XYZ.append([point_vertice.X, point_vertice.Y, point_vertice.Z])
							points_XYZ.sort(key=lambda x: (x[2]))
							points = []
							for i in points_XYZ:
								point_a = Point3d(i[0],i[1],i[2])
								points.append(point_a)
																					
						pts = Point3dCollection()
						for k in points[0:(len(points)/2)]:
							pts.Add(k)
						pts.Add(points[0])
						boundary_p3dcol.append(pts)

I get the following result: it appears that brep.Vertices results in a unordered list of points

image
image481×512 20.8 KB

The order of the first list is indicated in red below:

aa
aa902×829 7.38 KB

What I want to achieve is the order marked with blue: the Point3Ds are sorted clockwise.
If the point are sorted clockwise a closed polygon can later on be created for bounding a volume surface.

2

for k in points[:2]: pts.Add(k)
pts.Add(points[3])
pts.Add(points[2])

3

Swapping the second and thirth index works fine for rectangular solids with the script below:

                for id in boundary_id:
					obj = t.GetObject(id, OpenMode.ForRead)
					#find half of the vertices of a solid
					if isinstance(obj, Solid3d):
						brep = Brep(obj)
						vertices = brep.Vertices
						points_XYZ = []
						for i in vertices:
							point_vertice = i.Point
							points_XYZ.append([point_vertice.X, point_vertice.Y, point_vertice.Z])
							points_XYZ.sort(key=lambda x: (x[2]))
							points = []
							for i in points_XYZ:
								point_a = Point3d(i[0],i[1],i[2])
								points.append(point_a)
						#grab half of list, other half are top vertices
						points_filtered = []
						points_filtered.append(points[0:(len(points)/2)])
						pts = Point3dCollection()
						for k in points_filtered:
							pts.Add(k[0])
							pts.Add(k[1])
							pts.Add(k[3])
							pts.Add(k[2])
							pts.Add(k[0])
						boundary_p3dcol.append(pts)

This is however not applicable if the solid is not rectangular (e.g. has 5 base vertices). How can the script function regardless the amount of points in the solid?

4

you should look at faces and then at the edge loops then rather than immediately go for the veritces.

1 Like