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Geometry Intersection

Message 1 of 12
456 Views, 11 Replies

Geometry Intersection


I'm completely new to Bifrost, and I've got two questions: 


i) I've been following Ronald Reyer's fantastic 'Geometry intersection' tutorial, but I'm not quite getting the same results as him on the tutorial. On his tutorial, the viewport shows in red disks which points intersect between each other, but when I follow along, I get the opposite/inverse of what he's getting - all the points that aren't intersecting are showing up as red disks, while the intersecting points are not displaying anything - the disks disappear. Anyone know why this might be?


ii) On the 'Bifrost Browser', under Geometry Queries, there is a 'test_inside_mesh_example' which sounds very similar to Ronald's tutorial - can someone guide me on how I can use my own custom meshes with this test? Say if I wanted to have a 'characterA' and a 'ground' object, where would these plug into the 'test_inside_mesh_example'?


Thank you!

Message 2 of 12

Can you provide a scene file?

Message 3 of 12

Hey @morten.bojsen-hansen - I cannot sorry, this is on a work machine, and won't be able to export anything out.


Do you know if there's anything on any of the nodes that might inverse the visual red spheres like this?

Message 4 of 12

It's probably just a condition somewhere that got negated, but it's impossible to pin-point where without a scene file.

Message 5 of 12

Gah, ok - thanks @morten.bojsen-hansen 


How about point no.2 from my original post? The test brings in some 'create_mesh' nodes rather than the objects - is there some way I can connect the test up to my own geo?

Message 6 of 12

Yes, of course. Just replace either `create_mesh_sphere` or `create_mesh_cube` with your own geometry? You can drag geometry in from Maya by middle-click dragging the geometry from the outliner, or you can read geometry using any of the IO nodes in Bifrost (read_Alembic, ...).

Message 7 of 12

Hey, I can seem to get it working when I input my own sphere instead of the 'create_mesh_sphere' node, I can then move my sphere down and it shows me the red intersections. 

But, if I replace the 'create_mesh_cube' with say a pCube, I no longer see the red intersections on my two custom geo. My screenshot attached shows what I'm seeing on Bifrost, do you normally just connect the mesh1 of the pCube into the input of the 'pass_second_mesh'? 

Message 8 of 12

Hmm. It seems like that example doesn't like per-point normals. It works for me if I disable `Normals per point` on the geometry coming from Maya.

Message 9 of 12

Sorry @morten.bojsen-hansen - this is completely new territory for me; would you mind telling where do you see that 'normals per point' option to disable it?

Message 10 of 12

On the (cube?) node you dragged into Bifrost from Maya.

Message 11 of 12

You wouldn't happen to have time to send a screenshot would you? 😆 

Message 12 of 12

Ah! I've found it - sorry the node was defaulting to 'info' and not 'Parameters' - once I switched off the normals per point, it worked! Thanks!!

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