Hey all, this is an effect I’ve been interested in for a while now, every now and again I have a play and see if I can find a good way to do it, but as of yet I have not found a decent way to animated a crack in maya.
For example a floor cracking with the crack starting at one end and going to the other.
Hopefully one day I will make a tool to do this. But for now I would be interested in any method of how to do this as I have yet to find a decent method.
The one I used last was an animated boolean object but really dont like this method.
We’ve used blendshapes to accomplish this type of effect. Modelers works out inbetweens and it’s a simple hook up that can be animated. Cheap I know, but it definitely gets the job done.
I create a plane, then used split poly tool to draw the crack, bevelled it with 2 segment so it leaves original in place, move the original down a couple of units, then snapped the new edges along x,z to match the original crack so there is no crack to start with, then duplicated it and created the blendshapes.
Not too sure how to go about setting this up as a tool, will take plenty of thinking thats for sure, ideally I’m hoping to create it so I can draw a curve in the shape of the crack and use the tool to do the test.
We’ve used at least four ways to varying success and fidelity;
A skinned mesh with a non hierarchical skeleton, just animate the joints to open up the cracks as you need to. This has an advantage over blendshapes as far as authoring goes as you have much more control over how the crack propagates. However, your physics coders will have their work cut out to make it collidable.
Another similar variation to the above is to use a vertex shader to displace the verts of a mesh in a vector determined by vertex colour, and driven over time. Basically the same as a blendshape, but swapping mesh duplication for shader complexity.
Another method we’ve used is a decal system, and used scripts for animating their visibility to give the illusion of a propagation from a point. This is very much a low res effect.
A variation on the above is to use animated vertex alpha driven via a shader over time. This has the advantage that only one ‘crack’ overlay mesh needs to be created, in our case the alpha assignment was created via scripts.
You can tell we’ve thought a lot about cracking up.
We evaluated Blast Code a while back and we’re quite impressed by it. However, for our purposes, it was deemed too overweight and was more suited for a render pipeline than a budgeted game asset pipeline.
We did like the image based (crack maps) approach it had, and researched similar tools in Houdini with success.
Ive tried blast code in the past and it is very good, I was looking for more of a solution that would allow me to build a simple tool, I imagine the blast code methods are above my skill set.