Solid Subtractoin Having Odd Effect on Extrusion

[Josh NZ]

In the attached video I have an extrusion, I create a box and then subtract that box from the extrusion.

This operation causes the bottom of the extrusion to change shape.

Video will hopefully show more clearly the issue I am having.

 

 

[Benson Shaw]

Not sure why that is happening.  I have seen similar when manipulating objects with lots of vertices.  That floral extrude looks to have loads of points, or maybe some overlapping geometry that might mess up in the subtraction.

 

Perhaps a different approach would work - edit the extrude rather than solid subtraction.

I recommend paste in place a copy of the extrude into a new blank vwx file and test it in the new file:

Dbl Click the extrude to edit its source object (the 2d polygon).

Draw or paste the 2d rectangle onto the 2d poly at location where the box was.

Select both the rectangle and the polygon.

Clip surface & Delete the unwanted rectangular portion.

Exit the extrude. 

 

If that does not work as expected, post the test file to this forum thread so others can test.  Good luck!!

 

-B

[Josh NZ]

Thanks for the reply. I have also tried to clip the surface of the polyline before extruding but that operation doesn't clip the polyline.

Have attached the solid subtraction and a polyline with rectangle into a blank document. See Below.

 

 

Solid_Subtration_and_Clip_Surface_Issue.vwx

[Kevin McAllister]

Do you know about editing the clipping part of a clipped polyline like your lattice? If you select the lattice and use Ctrl [ it will allow you to just edit the clipping part. You might try clipping the rectangle there. You'll get a good sense of what's going on with the lattice (eg. how its composed) by doing this as well.

 

Kevin

 

[Kevin McAllister]

Another thought - you might try extracting the surface of the lattice using the Extract Tool and clipping that. Often the Extract Tool will correct errors when it creates the extracted surface.

 

KM

[AlanW]

@Josh NZJosh, If you are using the Mationette object it ends up a group so you need to ungroup and add solid then subtract the block from it.

HTH

Marionette_Wall_AW_170220.vwx

Edited March 5, 2017 by Alan Woodwell

[Josh NZ]

Thanks for all the help / tips guys.

[Benson Shaw]

@Josh - The lattice conspires to make that clip 2d or subtract solids 3d go bad.  Bottom row:

 

1.  "voids" are part of the perimeter, rather than holes in a continuous perimeter shape.

2.  There are several stacked points.

 

One fix is to remove and rebuild the bottom row.

In Top/Plan, my repaired lattice looks OK.  In flyover image, the color fill goes wonky, so there could be other problems.  But extruded version keeps color fill OK.

 

Modified file has B appended to file name so you can tell them apart.

 

HTH

 

-B

Solid_Subtration_and_Clip_Surface_Issue-B.vwx

Edited March 6, 2017 by Benson Shaw
still thinking about it

[AlanW]

Not sure why the screen goes bad but the process is as attached.. If you want to do it as polygons and not extrudes unhitch the extrude from the network then add surface then clip surface and you get the bottom result as a flat surface.

Edited March 6, 2017 by Alan Woodwell

[Phil hunt]

i think alan deserves a gold star for his contributions to our forum for all the time and effort he puts in to help other   thanks

[zoomer]

^ Indeed !

[Kevin McAllister]

Benson's observations are correct. It looks like the bottom piece of the lattice was created without the little circles where the points meet. I think those little circles would have prevented the geometry issues. When you use Modify>Edit Polyline (Ctrl or Command [ ) you can see where the geometry is different. VW is getting confused by the overlapping points at the ends of the petals.

 

Kevin

 

The highlighted areas in the image are the clipping objects of the polyline.....