I'm working on mechanical spider simulation, with many cables. To speedup simulation most of the time you would bake collision field made from animated spider to disk and then just use it for simulating cables.
What's the problem ? If you have animated object you need to turn on "Use Deforming Geometry". It will generate collision field for every frame of your animation. And that's the problem. In my example, some parts of the spider where moving only thru couple frames, others sometimes only on beginning and end of animation. Main body moved 100 frames, than stops and only front legs moves. And even if legs are moving that doesn't mean that all parts of them are moving all the time. That means that I was creating tons of unnecessary data in all those frames that objects where not moving.
I needed something that will manage turning On/Off "Use Deforming Geometry" for me.
Above video shows example of my solution. I use CHOPS to import object with a help of ObjectCHOP. Than I sum all channels (T[X,Y,Z], R[X,Y,Z]) with MathCHOP. After that I created my ACTIVE channel that will be used to manage "Use Deforming Geometry" on DOP object. With a help of ExpressionCHOP I check if there was any change in motion of my object between actual and previous frame. If there was I set ACTIVE channel to 1, if there was no change I set it to 0.
Attached video shows example of this technique applied to simple box with 30 uniform divisions. When "Use Deforming Geometry" was turned on thru all the frames, there was 113 files created and they took 8.5 MB on disk. With "Use Deforming Geometry" managed by CHOP trick, there was only 90 files generated and amount of disk space fell to 7.21 MB. There is no frame 2-12, 50-51, 53, 57-58, 63-65, 89-92 generated because there is no change in movement.
Now, armed with this technique, I made a test with my Spider animation. Before baked collision field files took almost 6 GB for 200 frames of animation. With CHOP trick amount of data fell to 4.3 GB. In some cases, for some parts, amount of generated data fell even below half of what it took before. And the baking time also fell quite considerably.
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