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Cut a face in the middle

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Cut a face in the middle

Posted by maxpenner at January 27. 2013

Hi folks,

I would like to split a face exactly in the middle within the Salome geometry module. I use Salome 6.6.0. When I select a face, I can see a cross through the face which shows me, that the face is selected. I would like to split the face exactly through these lines.

Is this possible? Maybe with python scripting?

Greetings, Max

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Re: Cut a face in the middle

Posted by William Tougeron at January 28. 2013

Hello maxpenner, :)

I propose this method in the GUI (no script needed):

A) For non-straight iso-curves:

  • 1- New Entity -> Basic -> Point, then last icon at the top right of the dialogue box (point on a surface).
  • 2- Create three points along the U-curve or the V-curve depending on what curve you want to use. Then close the dialogue box.
  • 3- New Entity -> Basic -> Plane, then second icon (plane from three points).
  • 4- Create a plane from the three points you created on your iso-curve.
  • 5- Operations -> Partition.
  • 6- You can then partition your face with your plane.

B) For straight iso-curves:

  • 1- New Entity -> Basic -> Point, then last icon also.
  • 2- Create two points at the extremities of the U-curve or the V-curve, with parameters 0 and 1 (no matter if the vertex go outside the surface). Close the dialogue box.
  • 3- New Entity -> Basic -> Line.
  • 4- Create a line linking the two points created on your iso-curve.
  • 5- Operations -> Partition.
  • 6- Partition your face with your line.

That's it :)

Of course, this could be easily scriptable :)

Best regards,

William

Re: Cut a face in the middle

Posted by William Tougeron at January 28. 2013

After reflexion, I admit that this method is not suitable for non-planar iso-curves (that can happen when the face was created from a filling, for example). In this case, you should rebuild the iso-curve with a spline. You can do it by creating not only three points but more than that on your surface, and from a parameter of 0 to 1. For example: 0 , 0.1 , 0.2 , ... , 0.9 , 1.

Then, to rebuilt the iso-curve: New Entity -> Basic -> Curve, then last icon.

You can then partition your face with it. If the partition fails, use Repair -> Limit Tolerance on your iso-curve or/and on your face to increase the tolerance during the partition. If it is not sufficient, you can extrude your iso-curve in an approximative face normal direction (New Entity -> Generation -> Extrusion, then third icon and checking the "Both Directions" box), and use the extrusion as a tool for your partition.

Best regards,

William

Re: Cut a face in the middle

Posted by maxpenner at January 28. 2013

Hi William,

thank you for your answer. Now I use the following solution:

1. Create three points via 'New Entity -> Basic -> Point' and select the last item 'construct with U and V parameters'.

I take the following parameters (By trying, I find which parameter U or V I must change):

  • U1/V1 = 0.5/0.5
  • U2/V2 = 0.5/0
  • U2/V2 = 0.5/1

2. If the three points are not colinear, I can create a new plane with them.

3. I create a partition with the face and the plane

4. I extrude the partition into faces and get two faces.

If I have a lot of such faces, I write a python script which does calculate the split faces.

Thanks again

Max

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