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Clipcube- Is this strange behaviour?


markdd

Question

In the picture below some extrudes render as solid objects and are filled red at the boundary of the ClipCube and some are open. I am confused as to what makes one extrude "Solid" and another hollow. (All the extrudes are made from closed polygons.) The only difference between them that I can find is that the "hollow" extrudes are part of a solid addition.5979dc4c28d7e_ScreenShot2017-07-27at13_25_17.png.9381cf767244b91cffd3bd17483e3069.png

When I ungroup the Solid addition I get what I would expect.

5979dd5c672a7_ScreenShot2017-07-27at13_32_18.png.08a0c7e7a48c1200491953f5e306fb4b.png

 

 

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17 answers to this question

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It is the standard problem with Extrudes.

The base 2D polygon had to be flipped (or reversed direction) while being extruded.

That is why not all face normals point outwards as they should.

 

I am just wondering why that problem persists embeded in a Solid Addition/Subtraction.

That makes kind of Solids from Extrudes. And for me that healed previous Extrudes

when Exporting to other 3D Apps so far.

 

And normally I was used to have no red clip faces at all for any Extrudes or its derivates

contained in PIOs.

Edited by zoomer
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intersecting Geometry?

 

Make two identical cubes, and have them "crash into" each other and then use the clip cube.. you should see similar behaviour.

When you do a solid addition to these cubes that behaviour will revert to normal.

 

On the extrudes source poly, make sure you don't have two identical polys over each other. that'll produce the same behaviour

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@RussUWhat I found in a clean file with two intersecting cubes was that the intersection was hollow, the rest solid. As you suggest, doing a solid addition made both solid. That is NOT what happened in the earlier drawing when undoing the solid addition made the extrudes solid when before they were hollow!

Screen Shot 2017-07-27 at 16.58.38.png

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So the clip cube has no problems with Extrudes problems itself as I mentioned at all,

but with overlapping Volumes.

That is fine.

 

So does that also happen when Objects just Touch ?

(no current VW availabe here atm)

The problem I see with clip cube section faces for multi component slabs ?

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15 minutes ago, markdd said:

simple extrudes

Can you post a file?

 

Doesn't need to be the whole thing, just copy/paste the problem stuff into a new file.

Just another thought though, OpenGL can have issues when your model is a million miles away from the file origin. Can you put a 3d locus at 0,0,0 to see how far away your stuff is?

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As far as I understood by your examples, it may not be related to Extrudes at all,

maybe just when 2 Volumes overlap that clip cube can't create the red section face ?

As your normal Extrudes look fine when not overlapping other geometry.

 

And just in your special file, where the typical self healing effect of Add/Sub Solid containers

doesn't effect as usual.

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You have discovered a bug.

I did this to reproduce.

Made a 50x50x50 cube. Duplicated it twice, to make three.

Then corner snapped the cubes to one another to make a staircase thingy... Added solids and then the clip cube presents the same weirdness.

 

I only got to it when I properly overlaid your geometry rather than snapping perfectly on edges. seems co-incident edges can confuse the cube. Can anyone else confirm?

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1 hour ago, markdd said:

Here is the file with the offending objects!

 

The 0,0,0 Point is very close by. The geometry is slightly wobbly as the file originated as a dwg probably made using some sort of point cloud device. I'm wondering if that is the source of the problem.... Take a look and see what you think.

Clip Cube.vwx

 

In this case its a geometry problem. VW doesn't do well when a single edge of two extrudes is joined. Its this point here -

 

597a3456c0a41_ScreenShot2017-07-27at11_41_02AM.png.c13b26db231674333b7122bd71989949.png

If I extend the height of the extruded stair down slightly like the others its fixes the issue.

 

597a3457e2870_ScreenShot2017-07-27at11_42_10AM.png.7ff2436ad3fa9f07f7968036993ad845.png

 

Kevin

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