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wood crack effect?


curveU

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Hello everyone, i'm working on some shots about wood crack effects, similar to the "Pirates of the Caribbean" wood explosions. I don't have much ideas on this. I already tried some methods, but can't achieve so many details. Could anyone here give me some advice on the general approach ? Thanks.

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  • 1 month later...

Edit: Moderator: this should perhaps be moved to the dops forum or something?

I'm also going to try to do this. In Lightwave I've tried working with clip-mapped sprite rendering of the particles (so-called sprite hypervoxels). I am sure this can be done in houdini as well but I don't know the software well enough yet. Also I would like to do fracturing with wood-like fractures, and not the concrete-ish fracturing you get with a standard setup. Combining some rather large chips from the fracturing with smaller ones that are just clip-mapped sprites seems like a good idea. Tips appreciated!

Edited by Truls
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A good workflow would be, as a starter, as Mawi said.

Achieve long shards with voronoi is a good start.

The first problem after this one is that you'll only get single shards and that is not good.

So after that you would want to glue some of the neighbouring pieces together to have the bigger pieces (that's some hand work, doing it procedurally CAN work but it's not that directable - example, take a piece every X pieces, see the neighbouring 3 pieces, and glue them together, for example).

Then you want wood debris. So probably something you will want to do is, after simming, take the pieces and see the separation. When it happens, then a vopsop could calculate the birthed points from the inner faces (with decay, so for example, after a face is separated, emit for 3 frames then stop) and feed them into a popnetwork to do the actual debris sim (then ideally you will want to take the pop into dop so you can have proper collisions).

And finally create some procedurals single little pieces of wood and instance them as the debris.

The bigger bottleneck I can see in all this process is that you will need LOTS of rbds, and that won't work with the ODE because we don't have a convexhull or trimesh collisions models, so you'll have to sim with the default houdini rbd solver, which can get slow (unless you have access to Bullet).

Hope that helped.

Cheers

Edited by Akabane
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Thanks all for the solution. I'm still looking for some better "procedural" approach to get the pieces with different sizes. I agree that Hand work is more directable, but any chance to get it done full procedurally?

The size will depend on how you scatter your pointcloud. More points = smaller pieces.

Try the clustering settings to glue pieces together.

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The size will depend on how you scatter your pointcloud. More points = smaller pieces.

Try the clustering settings to glue pieces together.

Yes, clustering should help re-glue the pieces together. Clustering works by looking at an attribute ("cluster" by default) on the incoming Voronoi cell points and re-attaching all the pieces that come from points with the same attribute value, including deleting any internal faces, so you get proper refraction when raytracing. You can add random, Cell Noise-based cluster values on the VoronoiFracture asset itself, or you can set those values ahead of time in any way you like. Setting a point's cluster value to a unique number ($PT for example) will guarantee that a particular piece stays unglued.

The VoronoiFracturePoints asset does a lot of setting these values to control fracture patterns if you want to look inside.

Edited by johner
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