automaticly share coincident topolgy

[magicprograming]

I am trying to randomly build some objects on an existing object. While using SpaceClaim, I noticed a tool for sharing coincident topology:

I also came across some prepare tools that seem to have similar functionality:
https://geometry.docs.pyansys.com/version/stable/api/ansys/geometry/core/tools/prepare_tools/PrepareTools.html#ansys.geometry.core.tools.prepare_tools.PrepareTools

However, after using the share_topology function, I didn’t observe any improvement. I then tried the enhanced_share_topology function, but it resulted in an error:

Is there an alternative way to achieve this? Or am I misunderstanding how these tools are supposed to work?

[RobPasMue]

Hi @magicprograming - based on the error message you are getting, it seems to me that the version of PyAnsys Geometry that you are making use of does not have the method enhanced_share_topology. Also, just so you know, this method is only available starting on Ansys release 25R2 (mid year 2025)... so it is currently only available for internal developers.

Would you be able to share a model where you are trying to apply a share topology? What version of Ansys are you making use of and what is your PyAnsys Geometry version (run pip list --> and search for ansys-geometry-core)

Thanks in advance!

[magicprograming]

Thanks for your quick response! I really appreciate your help.

Here are the details:
Ansys version: 2024R2 Student
ansys-geometry-core version: 0.9.1 (confirmed via pip list)

Here is the model I used
https://drive.google.com/file/d/1GPmnFa1ufx5MbKxHrarO8Fn_O6uASpdJ/view?usp=sharing

Here’s the code I’ve been using, where I attempt to add small buildings into the existing fluid region.Thanks again for taking the time to assist me!

from ansys.geometry.core import launch_modeler
from ansys.geometry.core.designer.component import Component
from ansys.geometry.core.math import Plane, Point3D, Point2D, UnitVector3D
from ansys.geometry.core.misc import UNITS
from ansys.geometry.core.sketch import Sketch
from ansys.geometry.core.tools.prepare_tools import PrepareTools
from pint import Quantity
from enum import Enum
import numpy as np


#define layout
class layout_type(Enum):
    in_line = 1
    stagger = 2
    manual_input = 3
urban_layout = layout_type.manual_input

#manual_input
input_position = [(25,10),(21,3),(20,8),(18,5),(14,7),(10,10),(8,4.5),(4.55,4.5)]

#design details
buildings_per_row = 4
buildings_per_col = 2
building_radius = 1.725 #in m
building_diameter = 2 * building_radius
building_height = 5.7 #in m
max_street_width = 2.35 #in m

#boundary conditions
boundary_x = 26.8
boundary_y_1 = 0.58
boundary_y_2 = 12

#number of building
if(urban_layout == layout_type.in_line or urban_layout == layout_type.stagger):
    buildings_number = buildings_per_row * buildings_per_col
else:
    buildings_number = 8
    #check boundary conditions
    for a in range(buildings_number):
        x, y = input_position[a]
        if (building_radius >= x) or(x >= boundary_x - building_radius) or (boundary_y_1 + building_radius >= y ) or ( y >= boundary_y_2 - building_radius):
            print(f"ERROR:{input_position[a]} is out of boundaries")
            break          
        #check overlap
        for b in range(a + 1, buildings_number):
            distance = np.linalg.norm(np.array(input_position[a]) - np.array(input_position[b]))  
            if distance < building_diameter: 
                print(f"ERROR:{input_position[a]} overlap with {input_position[b]}")

#start to create
modeler = launch_modeler()

design = modeler.open_file("New_Geom.scdoc")

# sketch building
building_sketch = Sketch()
building_sketch.circle(Point2D([0, 0], UNITS.m), Quantity(building_radius, UNITS.m))
building_body = design.extrude_sketch("Building", building_sketch, Quantity(building_height, UNITS.m))

#create position matrix
max_street_width += building_diameter
row_mid = (1+buildings_per_row)/2
col_mid = (1+buildings_per_col)/2
position = []

if(urban_layout==layout_type.in_line): 
    for i in range(1 , buildings_per_row+1):
        for j in range(1 , buildings_per_col+1):
            position.append(((i-row_mid) * max_street_width + 13.4 , (j-col_mid) * max_street_width + 6))

elif(urban_layout==layout_type.stagger):
    for i in range(1, buildings_per_row + 1):
        for j in range(1, buildings_per_col + 1):
            position.append(((i-row_mid) * max_street_width + 13.4 , (j - col_mid) * max_street_width + (i % 2) * ((max_street_width)/2) + 6)) 

elif(urban_layout==layout_type.manual_input):
    position = input_position    
max_street_width -= building_diameter

buildings = []

#build the buildings
for i, (dx, dy) in enumerate(position, start=1):
    new_building = building_body.copy(parent=design)
    new_building.translate(UnitVector3D([1, 0, 0]), Quantity(dx, UNITS.m))
    new_building.translate(UnitVector3D([0, 1, 0]), Quantity(dy, UNITS.m))
    design.create_named_selection(f"cask_{i}", bodies = [new_building]) 
    buildings.append(new_building)

design.delete_body(building_body)

#add fluid_air-fluid to the list
buildings.append(design.components[1].bodies[0])

#share topology
modeler.prepare_tools.share_topology(bodies = buildings, preserve_instances=True)

#export result
output_path = "Geom"
design.export_to_scdocx(output_path)
modeler.close()

[RobPasMue]

Hi @magicprograming - after checking on my side, it seems that the share_topology method is doing what is expected... finding the shared topology by the bodies passed. However, they do not seem to share any common surface. Are you sure you are not missing the fluid or fluid_air component? That would give you the shared surface between the bodies and the overall fluid region for example - if that's what you are interested in =)

[magicprograming]

Hi @RobPasMue ,
Thank you for your response! I appreciate you taking the time to clarify how share_topology works.
As you mentioned, I am particularly interested in the shared surface between the bodies and the overall fluid region.
I have ensured that fluid_air is added to the list as follows:

#add fluid_air-fluid to the list
buildings.append(design.components[1].bodies[0]) 

Additionally, I printed out the buildings list to confirm that it includes the fluid_air component.

Despite this, the results still appeear to differ from what I observe when using the "Share Coincident Topology" function in SpaceClaim.

For instance, after runing the code for share_topolgy, the bottom part shows the following:

However, if I then manually apply the "Share Coincident Topology" function in SpaceClaim, most of the parts that should be shared are still detected:

This discrepancy leads me to wonder if I am missing some critical step or configuration in the share_topology method. Could you provide further insights or suggest what else I might need to check to resolve this issue?

Thanks again for your support!

[RobPasMue]

I know that there were some tolerance issues when the value passed was 0. You can try to pass in a certain tolerance value just in case: https://geometry.docs.pyansys.com/version/stable/api/ansys/geometry/core/tools/prepare_tools/PrepareTools.html#PrepareTools.share_topology

Otherwise, I might have to reach out to some of my colleagues internally so that they can help you out. My knowledge on the internals of the SpaceClaim Share Topology feature are limited

[magicprograming]

Thank you for providing a great solution to the problem! I passed tol = 0.0001, and it successfully shared the topology.
Maybe the tol should be a required input in the future.
I really appreciate your help!

[RobPasMue]

I completely agree! I think we should make it a compulsory argument! Thanks @magicprograming!