catchyid Posted September 19, 2019 Share Posted September 19, 2019 Hi, In Bullet simulation, pieces are packed and have attributes : (1) P , (2) orient quaternion, (3) pivot. Somehow, these three attributes compute the final transformation matrix for each piece. My goal is to animate these simulated pieces in reverse (not just playback in reverse, but instead create more "interesting" animation). My question is how are Pivot and P related? Initially, P equals Pivot, then as the simulation goes: Orientation changes (which is logical), and Pivot drifts away from P (i.e. not equal anymore). I checked bullet[T|R|S] are they are all zero or identity. Thanks, Quote Link to comment Share on other sites More sharing options...
StepbyStepVFX Posted September 19, 2019 Share Posted September 19, 2019 If I remember correctly, if you want to use the intrinsics of your prims coming out of sim, to instance higher rez objects on the points, or maybe use CHOPS to smooth / reverse / tweak the sim, the equation should be like : Ppoint = Pprim + (Ppoint - PIVOTprim) * TRASNFORMprim where PIVOT and TRANSFORM are respectectively a vector and matrix3. Ppoint should be static (position of the points at start of the sim). Hope this helps 1 Quote Link to comment Share on other sites More sharing options...
StepbyStepVFX Posted September 19, 2019 Share Posted September 19, 2019 I think you’ll find better info her : http://www.tokeru.com/cgwiki/index.php?title=HoudiniDops#Rigid_Body_Dynamics Quote Link to comment Share on other sites More sharing options...
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