"Bad" mesh after cut operation - Forum Open Cascade Technology

jack-wangss
Wed, 07/12/2023 - 07:15

Forums:

Modeling Data and Algorithms

S1 is a pipe shape from a profile with curve, S2 is a box.

After cut operations, the mesh of S1 became "bad"

Attachments:

before_cut.png

after_cut.png

after_cut_mesh.png

Thomas Hafemann
Wed, 07/12/2023 - 10:36

Are you using BRepAlgoAPI_Cut?
Make sure that all objects are OK before cutting.

I recently had a Problem with this function. In my case there was a face with an overlapping edge. It was not visible, but testing the wire showed that it was not closed. After fixing the Wire and creating the new face the cut operation worked.

jack-wangss
Wed, 07/12/2023 - 13:25

Yes, I am using BRepAlgoAPI_Cut.

It is the S1 shape problem, but I am not sure how to fix it.

I used BRepOffsetAPI_MakePipe to create the S1 shape by a profile, at first, everything is ok, but when I used a mat4 to scale the profile, the result came to wrong.

But I need scale the profile, so I don't know how to fix it.

Attachments:

before_use_mat4_to_profile.png

Dmitrii Pasukhin
Wed, 07/12/2023 - 13:46

Please try to use ShapeFix_Shape on this shape.(TKShHealing.dll)

Best regards, Dmitrii.

jack-wangss
Wed, 07/12/2023 - 18:35

Thank you for your help.

I used code below try to fix the profile face, pipe shape and cut shape, but all failed.

ShapeFix_Shape fixer(pipe.Shape());
fixer.Perform();

Mikhail Sazonov
Wed, 07/12/2023 - 22:26

If you just use mat4 to scale to the shape directly it is wrong. You need to use the algorithm BRepBuilderAPI_Transform to apply the scale transformation.

jack-wangss
Thu, 07/13/2023 - 04:30

Here is my code for scale profile face, is that right？

NCollection_Mat4<float> mat4;
mat4.SetValue(0, 0, width);
mat4.SetValue(1, 1, height);

gp_GTrsf trsf;
trsf.SetMat4(mat4);
BRepBuilderAPI_GTransform transform(profile, trsf);

jack-wangss
Mon, 07/17/2023 - 11:42

I have solved this problem by convert arcs in profile into mutiple segments.