Real-Time Physics Simulation Forum

The behaviour of rigid bodies _should_ be independent of the overall mass scaling (so if you multiply the masses of all objects by some constant, it shouldn't change the behaviour). Physics engines will probably not be that perfect, but I would have thought would be OK for what you describe (can't b...

I have a box on an plane. The plane is inclined by an angle phi. The friction parameter "mu" is set to 0.35 on both of them. Normally the friction coefficient in physics engines is calculated either by a lookup table, or by multiplying a friction parameter on each surface. So, assuming th...

Looks like a great integration to me! Hope lots of people find it useful.

I'm not sure that this is a very fair performance test for the engines! Engines will be optimised for more than one body, and also probably for bodies in contact rather than unconstrained. For example, when I run the PhysX test case I get timings of around 0.07ms, for one sphere falling. However, th...

I set gravity 20 instead of 10. Slightly better but still not realistic. If you want to do a direct comparison with your cell phone then you would need to set gravity to around 500. This should result in relative motions being the same (i.e. the same amount of world time to rotate one revolution, o...

Most physics engines optionally add some simple damping to aid stability. I've not checked, but it may be that Bullet has this non-zero by default.

It's behaving like this because when a capsule is rolling on its end like in your video, it spins much faster than a cylinder would for the same linear velocity, so it behaves strongly as a gyroscope. Rather than the non-contacting end falling down, the capsule rolls in a circle (to the left in your...

This is a stab in the dark, since I don't use Bullet... but if the solver is aiming to eliminate the penetration error (or some fraction of it) over a fixed number of updates using Baumgarte stabilisation, then a very small timestep will result in large error-correcting velocities because they'll be...

If you don't detect overlap between the sphere and the mesh, you want to check if that's because the sphere centre is completely inside the mesh. If your mesh is closed, then you can tell if a point (i.e. the sphere centre) is inside it by doing a ray test in some arbitrary direction. If the number ...

Can't help with the Bullet-specific stuff, but

Units of impulse = mass * distance / time

Units of energy = mass * distance^2 / time^2

so your calculation (energy = impulse * impulse) must be wrong anyway...

STLport sounds like a good option, though I somehow doubt that it has the same debugging support in Visual Studio as MS STL has, esp. being able to see the size and any entry in a std::vector. You can customise the way types are displayed in Visual Studio by editing: Common7\Packages\Debugger\autoe...

Same error as before...

i disagree passionately, i mean, if its not VERY, VERY obvious what "visual errors" im talking about then i must assume something is wrong with my computer... 1. It is possible that your computer returns weird timing results (I saw this very occasionally a while back with one or two peopl...

Other physics SDKs, like Havok and Ageia also clear out the force after the simulation step I think, but I need to verify. Whatever other SDKs do... the idea of clearing the force after each simulation step has never made sense to me for two reasons: 1. The force is quite clearly "owned" ...

One of the soft body demos in Bullet already simulates this, and it's pretty cool.