Real-Time Physics Simulation Forum

It's perhaps similar, but I'd be very surprised if you couldn't get GJK/EPA to work with some modification. I don't think the Minkowski difference is usable, but some sort of erosion CSG type thing might work instead? It should still produce a convex region, which you should still be able to walk wi...

Is there a way to leverage GJK or EPA for hollow shapes? Imagine this case: triangleInsideSquare.png You want to keep the red triangle inside the black square. In the case in the picture you'd want there to be no collision. But vertex A is *almost* touching the edge, so the distance/separating vecto...

Yeah, that's actually the approach I'm exploring right now. I'm sort of off on my own in left field at the moment, though, so I'm looking for some perspective.

As a motivating example, imagine a mass of 1e5 kg resting on top of a mass of 1e-5 kg resting on top of the floor. What's the force that the smaller body has to deliver to the larger body to keep it from falling down? Basically gravity * 1e5. And then, by Newton's third law, what's the force that t...

Yes, I'm familiar with that approach. I was specifically interested in getting comfortable with the mathematics, though. I'm going to be exploring building the hessian matrices of a reduced coordinate system, which is a much harder problem! So I wanted to exercise my math chops and make sure I can d...

I'm working on a collision detection algorithm, and I'm looking for alternatives to GJK for calculating the "distance" between two convex polyhedra. At this point performance isn't a concern, as it's very speculative research. Instead, I want these basic properties: 1. The distance functio...

Ah, hmm, I think I figured it out. d cos θ(t) -sin θ(t) * dθ(t) ---------- = ------------------- = -sin θ(t) dθ(t) dθ(t) That is, I'm not finding the derivative with respect to time, but with respect to θ(t). So the derivatives on the top and bottom cancel, and w drops out of my Jacobian.

That wouldn't help actually. The core of the problem is that the mass matrix's condition number (basically your largest mass divided by your smallest mass) gets propagated to the larger equation. You need to find the inverse of that matrix, and inverting a matrix with a large condition number is ill...

A good way of handling collision response between bodies with vastly different mass ratios would be a reasonable project. It's not that it's an open problem so much as it's an unexplored problem. The onus is usually on the users to make the system less extreme by tweaking the masses. See, eg, this p...

I'm trying to get my mathematical ducks in a row and finally tackle building Jacobians for a constraint using partial derivatives. In the past I've sort of messed around with what I want the constraint to do in velocity space and built up the Jacobian that way. But this time I'd like to tackle doing...

Hmm, would it be fair to say that research isn't disseminated via papers/articles then? Most of the new work I'm familiar actually does come from blogs and the like.

I'm curious what journals articles on continuous collision detection have shown up in? As far as I know, there aren't any specifically for CCD, so they tend to get written up in ones for graphics, like SIGGRAPH papers and the like. The small library of articles I'm aware of tend to be 15+ years old,...

They're just tuning values. They don't necessarily correspond to any real values for things (the damping and spring constants for resting contacts have real world analogies, except that resting contacts aren't really springs, so again the values are just for tuning). Play with the values until you g...

The problem with that is that physics is a global phenomenon, so it doesn't lend itself well to massively parallel execution. By contrast, one triangle/pixel renders pretty much the same as another, regardless of what the other elements are doing. There are a few serial elements to rendering, though...

I like the red text I'm sure there'll still be some but hopefully this lowers the number at least. The rest should be manageable by moving the threads.