How are ERP and CFM computed when two bodies collide?

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lamilana
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Joined: Mon Sep 30, 2019 9:47 am

How are ERP and CFM computed when two bodies collide?

Post by lamilana » Fri Oct 11, 2019 12:03 pm

Dear Bullet community,

I read about the equivalence between stiffness, damping, CFM and the ERP in the ODE user manual and in Erin Catto's excellent "Soft Constraints - Reinventing the Spring" talk at GDC2011.
I am especially delighted to see that Bullet even allows directly setting the stiffness and damping properties for each link, so that we don't have to compute the CFM and the ERP ourselves.
What I am wondering, however, is how these are computed when two bodies with different stiffness and damping values collide. This will lead to one contact point, so we have to determine one CFM value and one ERP value, right? If so, how can we compute these based on the two stiffness and two damping values?

Many thanks in advance!
lamilana

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