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Collision object shape

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Collision object shape

Unread postby atnreg » Mon Jun 12, 2017 3:13 pm

Hi!

Collision detection works perfectly with bounding box and ellipsoid.

But does it always use bounding box or ellipsoid of whatever object is given as collision object? It seems so and that restricts the use quite a bit.
That way the manual example is not actually working completely because there is undetected area under the tree foliage so the grass can go inside the tree trunk. Am I missing something or is this really like that? :)

The best would be that you could use any object as collision but Clarisse could warn if the object is likely to cause problems but still would allow to use any.

Box is not good shape anyway because it has corners. Ellipsoid is better but still prevents holes inside the actual object.

So if it is possible, can you please give an example how to make say a torus and small spheres to scatter correctly, i.e. spheres would be placed inside the torus 'hole' and also around it without overlaps :)

Of course there is workaround for this thanks to particle painting and it may be too heavy to implement real geometry collision detection :)
Edit: and now with bakeable scatterer that is even possible to do using occlusion (bake the torus scatterer and use it as occlusion for sphere pointcloud) :)

Thanks!

Antti
Intel i7(6-core),32GB RAM,NVIDIA GTX690 (2GPU)+GTX Titan Black,Win10Pro 64bit
Clarisse 3.5RC2,Blender,(3D-Coat,ZBrush,Lightwave+Octane etc.)
Clarisse since 2016-09-29, Python since 2016-11-10 (Clarisse Py 2017-01-04)
I do all 3D stuff for fun, no business
atnreg
 
Posts: 172
Joined: Mon Sep 19, 2016 5:20 pm
Location: Helsinki, Finland

Re: Collision object shape

Unread postby adomon » Tue Jun 13, 2017 12:09 pm

Hi Antti

For the moment, collision detection may only be performed on instances oriented bounding box or ellipsoid.
If you are using collision object, depending of the mode, the collision will be performed with the oriented bounding box or the ellipsoid determined from the collision object itself.

Of course this may be a restriction, and it is on our roadmap to specify more bounding volumes for collision detection, but the real primitive-primitive intersection will be probably not implemented, because of the potentially huge amount of computation it requires.

Regards

Antoine
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adomon
 
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Re: Collision object shape

Unread postby atnreg » Tue Jun 13, 2017 12:14 pm

Ok, thank you for clearing this up, it was like I thought but now I know for sure :)
And yes, real geometry collision detection would probably be too heavy for Clarisse's typical scenes :mrgreen:

Antti
Intel i7(6-core),32GB RAM,NVIDIA GTX690 (2GPU)+GTX Titan Black,Win10Pro 64bit
Clarisse 3.5RC2,Blender,(3D-Coat,ZBrush,Lightwave+Octane etc.)
Clarisse since 2016-09-29, Python since 2016-11-10 (Clarisse Py 2017-01-04)
I do all 3D stuff for fun, no business
atnreg
 
Posts: 172
Joined: Mon Sep 19, 2016 5:20 pm
Location: Helsinki, Finland


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