Coder Corner

Let’s debunk some more.

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Trying out some more of the APE’s scenes. PhysX version is here. Original is here.

I didn’t put the crane itself yet but the cables are the hard part. Also I made the capsules thinner, to make it more difficult to simulate.

In the Unity thread you can read that:

“This new crane model was pushed to the extreme with the following modifications:

1) Reduce from 5 ropes weight attachments to 4 ropes
2) Increased the main rope’s length for an additional 5 segments
3) Increased the mass ratio between a single rope segment and the cargo box to 1:1000. No commercial physics engines I’ve used before handle such HUGE mass ratio between joined rigid bodies. The common guideline from PhysX and Havok is less than 1:10. Literally you’re lifting a ton with a kilogram ! This is probably overkill for most games. However if you do want to simulate extremely heavy weight sensation, here you go!”

So the mass ratio is 1000:1 in my test, and as you can see it works just fine. You simply must use the right PhysX feature (articulations) for the job.

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Bonus:

I was at the playground with my kid and we were doing this with the swing set. I wondered if it would work in PhysX. It did

Capsules have a mass of 1. The box has a mass of 1000. Timestep is 1/60. This is again using PhysX’s articulations feature.

It somehow reminds me of these “rubber effects” we did in demos on the Atari ST