Real-Time Physics Simulation Forum

Antonio, I just looked at the Havok demos you mentioned. It pretty obviously shows that all, but the stiff chain solver looks very bad or doesn't work at all in my opinon. Though it appears you might get away with a stiff solver for joints only and handle limits and (if needed) motors in a relaxati...

This makes me feel that physics-based animation blindly driven by kinematically-driven target poses (that just keep playing forward ignoring the physics) doesn't seem all that much better than simply eschewing physics and sticking to kinematic animation. in fact you should have sensors that can inf...

Basically the body is kinematically driven by setting the state at everyframe and then the solver is called. Wouldn't the solver overwrite the angular velocities in this case or can we assume that the velocities will satisfy the constraints - at least more or less? i tried that approach in a accele...

I wonder if the motor torques can have reasonable maximums for mo-cap animations. I know that hand animated movement has absurd accelerations (I've seen 20 x gravity). in games animations can indeed be much faster than in reality, one idea could be to see them as having the same torque limits but w...

From reliable but anonymous sources Natural Motion and Dance both work with joints and motors using an iterative solver like Bullet's sequential impulse or quickstep. So Featherstone or direct pivoting LCP solvers like Dantzig seem not strictly necessary, although it might help. Natural Motion powe...

All engines you mention have the constraints you need. I think Erwin is working on a Featherstone solver, but I don't know how far he is with this. If you are looking for motors I know for sure that Ageia and ODE support them. For Bullet I can't say. So from this perspective all engines are more or...

http://www.custompc.co.uk/news/601680/amd-considers-buying-ageia/page1.html http://www.theinquirer.net/gb/inquirer/news/2007/11/22/amd-will-not-buy-ageia "As far as I can see there’s really no news here. Everyone in the industry understands that Ageia’s primary aim is to just to be bought, and ...

Here's a quick test; for some reason (e) makes things unstable (adds energy), quite possibly an implementation error. The PBD formula is definitely better than the one I've been using, and using Q the Kalman method converges even better. i have just managed to run the code you posted, Q in fact see...

I tried the several algorithms for position correction of Box2D’s revolute joint. ... interesting comparisons, if i read it correctly they are also consistent with what intuition suggests, the more up to date the used information is(effective mass, positions, jacobians etc...) the better the soluti...

I think I'm a bit confused about row and column vectors; K is definitely a column vector, as is X, but is J a row vector? If so, this would mean that K*J is an outer product, which would explain my problems as I assumed it was an inner product. Initially I just assumed everything what whatever was ...

isn't A*B diagonal for any A, so long as B is diagonal? no, set B to identity A*I = A a*B is diagonal when a is a scalar and B is diagonal. i think you tried to simplify it a bit before getting it to work, i just used a generic mxn matrix library for my tests as i wanted to exclude any other source...

Here's a quick test; for some reason (e) makes things unstable (adds energy), quite possibly an implementation error. The PBD formula is definitely better than the one I've been using, and using Q the Kalman method converges even better. I still need to add some mouse-interaction and figure out wha...

Working through a-d (skipping e, and using Q=0, R=0) I get eq9 in the PBD paper; this is the same formula as Dirk's most recent post. If I understand things correctly, my ad-hoc formula is equivalent to using a non-zero value for R; I'm going to try a sanity check implementation of a simple chain o...

raigan2 wrote:

AntonioMartini wrote:K is the equivalment of the ERP

Do you mean S? I'm confused..

yes S sorry, thanks for pointing that out, i have edited the post.

cheers,
Antonio

I may be incorrect as far as construing the PBD solver to be doing a least-squares-fit/optimization process, the formulas simply seem very similar to Newton-type optimization. I would _really_ like to understand why my formula works so much better, and what the optimal formula is -- this is what in...