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jit.gl.model, keep mesh coherent when applying vertex manipulations?


dtr
May 31, 2014 | 3:13 am

Hi there,

I have an issue with manipulating imported 3D models. I want to do vertex manipulations on them, using matrixoutput. The issue is that it seems that the models I create in Maya – or the way jit.gl.model interprets them – is that meshes are built up of triangle faces, and each triangle has its own 3 vertices. This means that every mesh vertex actually has 5 or 6 vertices at that position. One for each triangle that joins in that point.

Now when I do operations on the vertex matrix, for example adding noise to it, these vertices in the same position split up. The patch below demonstrates that. When I add noise I’d like ducky to deform but keep mesh connected. Though what happens is that the individual triangles disconnect in a kind-of explode effect. That’s because the triangles don’t share vertices in a triangle-trip fashion.

How can I prevent this from happening? Is it an export setting in Maya (I = modelling noob)? Or can I do something in Max?

Tanx for all help, Dtr

– Pasted Max Patch, click to expand. –

June 1, 2014 | 4:35 pm

(Not behind the computer right now)
Try the same technique on a basic jit.gl.gridshape and see if you get the same results. Eg. jit.gl.gridshape @shape plane
or
@shape cube

When I export models from blender I use the triangulate modifier and everything seems to displace fine without exploding into separate faces. With jit.gl.render @draw_primitives triangles



dtr
June 2, 2014 | 3:39 am

Thanks for chiming in. The transforms work fine with gridsphape and other geometry generated in Max.

I got some Maya tips from friends telling me to merge vertices before exporting. Didn’t help.

What file format do you export to from Blender? Could you perhaps give me a Blender generated model that I could test with?

I’d be happy to switch to Blender if that solves it. Need to learn modelling from scratch anyway.


June 2, 2014 | 7:25 am

Just download blender.
Add a cube.
Use a subdivision surface modifier
then a triangulate modifier

Export as a .DAE file with the settings in the screenshots.

Because its exported with the modifiers applied then you can do none destructive editing and always go back and alter the geometry.

Always check that you merge double vertices.
And with jit.gl.model I turn off some option which allows jitter to change the vert order. Not sure what it is anymore.

Attachments:
  1. Screen-Shot-2014-06-02-at-16.21.41
  2. Screen-Shot-2014-06-02-at-16.22.43

June 2, 2014 | 10:44 am

And with jit.gl.model I turn off some option which allows jitter to change the vert order. Not sure what it is anymore.

possibly @optimize ?


June 2, 2014 | 10:46 am

Just looked it up, thats the one Rob !
If thats off then you know that the vertex order is exactly "the way " it should be.


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