Real-Time Physics Simulation Forum

I think your explicit scheme is supposed to be using f_n, not f_n-1. So using an external force is the same as an explicit scheme. But this might be alright if the external force isn't very high-frequency.

It's true, people aren't interpreting 'General' as truly general, but rather general within the context of Bullet. OTOH, something like "General (Non-Bullet Specific) Discussion about Collision Detection and Physics R&D" is a bit long.

I was just at the OpenCL site the other day, and I think they have an example program for cloth simulation, but I didn't note if it involved collision.

I think the idea you are looking for is the "least squares plane fit" - you might do a Google search for that. I know David Eberly, for one, had a fairly simple code snippet for finding it. If you can't find it, I may be able to dig it up.

I assume everyone who ever faces collision detection and response encounters this same problem. Yup. First off: a fractional rotation using matrices would usually involve converting the 3x3 matrix into a quaternion or axis&angle. Apply the fraction there, and then convert back to the matrix. I ...

That's a good question. I'm not sure about all compilers and platforms, but at least the MS compilers on PCs have a 'strict' floating point mode which gives up a little performance to ensure IEEE standards. And I don't actually know if this makes it deterministic or not. At some point I came across ...

I understood where you were going with that, but the problem is the "butterfly effect". A small difference early that may be easily filtered out by the conversion can still lead to a big difference later that cannot. EDIT: and I might note that most accelerated floating-point calculations ...

there really aren't any truly deterministic (that is to say deterministic across platforms/architectures/compilers) 3D physics engines out there ... due to floating point calculations, right? The physics engine would be free to perform its calculations with hardware-accelerated floating point value...

I could be wrong, but I think you have to solve the constraints at the acceleration level rather than the velocity level if you want to use a generic integration scheme. Presumably, it's because solving constraints at the velocity level interferes with the normal generic integration of velocity, whi...

Is the international units (meter, Newton, Pa) used in Bullet Physics? Thank you. Yes. I have faced only the problem determining btRotationalLimitMotor::m_MaxMotorForce units. In my experiments the unit is not "Newton * meter". I will be very appreciated if someone explains the meaning an...

Can anyone summarize in a sentence or two what exactly the Newton solver does? From their main page, it says, "Our engine implements a deterministic solver, which is not based on traditional LCP or iterative methods, but possesses the stability and speed of both respectively."

I don't immediately spot a problem there. But my question was how the interpolation was done. What uses the interpolation parameter and how does it?

So I limited the game to 60 fps and did as you said: : : It doesnt seem like the time between each render is the problem :S Agreed. OK, so maybe something about the actual interpolation is going wrong (as you originally suggested). I assume from your render loop that "particles" are the o...

Yes, delta time. If indeed the problem is a slow graphics frame, the hard part will be figuring out why. I'm not a graphics expert nor do I know what you're rendering, but there's a long list of possible causes: cache misses for either RAM or video textures, vsync issues, another high-priority app r...

I'd probably log out your ETs and DTs into a file, play the game until you see the jutter, then stop and graph out the data real quick. Hopefully the jutter will stick out like a sore thumb. My experience is that (for whatever reason) you've got a slowly drawn frame with a much bigger than usual DT,...