Search found 26 matches
- Fri Oct 31, 2008 10:42 pm
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: ApplyForce() adds excess energy
- Replies: 3
- Views: 4807
Re: ApplyForce() adds excess energy
While that whole thing is probably worth reading anyways, the quick answer is that there's no requirement that the same force over the same time adds the same amount of energy; change in energy is the integral of the force over distance (dotted appropriately, of course), not time, so the answer is t...
- Tue May 20, 2008 10:36 pm
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: CA and numerical integration and root finding
- Replies: 18
- Views: 15409
Re: CA and numerical integration and root finding
However, I put a ball inside that box, eventually the ball will tunnel outside of the box (yet remain inside the static region). I believe this shortcoming to be related to linearization of rotational motion. For example, the velocity of a pendulum is tangent, yet it moves inward. There could also ...
- Mon May 19, 2008 11:56 pm
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: CA and numerical integration and root finding
- Replies: 18
- Views: 15409
Re: CA and numerical integration and root finding
Instead of calculating progressive conservative advancement steps and integrating the entire simulation, every body computes it's exact time of collision whenever it doesn't know its next time of collision. When the time of collision arrives, we solve the resulting island (that's the proper term, r...
- Wed Feb 13, 2008 9:06 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Collision normal perturbation
- Replies: 2
- Views: 4308
Re: Collision normal perturbation
This could be interesting if it works, particularly when applied in conjunction with visual bump or parallax mapping. However, there are pitfalls. First, make sure your normal vectors aren't causing collision resolutions to pump energy into the system - your normal vector field should be curl free, ...
- Sun Jan 06, 2008 11:25 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Newton's cradle
- Replies: 8
- Views: 17612
Re: Newton's cradle
Jan - I saw the videos (very nice work, btw!) and took a look through your paper, and I had a couple questions. Based on a quick reading, it seems that one distinction between your method and SI (at least as far as solving Newton's cradle goes) is that in SI one iterates over the contacts several ti...
- Thu Dec 13, 2007 5:35 am
- Forum: General Bullet Physics Support and Feedback
- Topic: Java Bullet
- Replies: 3
- Views: 3387
Re: Java Bullet
Please keep us informed if you're going to do this, I'm very interested in seeing this happen. If I have some time, I'd be willing to help, as I'm very much in a porting mood from working on a Box2d Java port (http://www.box2d.org). One suggestion, it might be a good idea to start from the XNA port ...
- Sat Oct 20, 2007 5:04 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Rope Physics in 2D
- Replies: 3
- Views: 11083
Re: Rope Physics in 2D
Well, good luck with it - if you need any help, let me know, I have used this method in games before: http://www.ewjordan.com/rgbDemo/ has a Java demo (applet) of a game I did this in, which is still unfinished. If you're on a 64 bit machine it might not run, it uses JOGL and I don't think I have th...
- Thu Oct 18, 2007 5:45 pm
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Newton's cradle
- Replies: 8
- Views: 17612
Re: Newton's cradle
[Sorry, this is really long: long story short, don't hit your head against this stuff too much, there's no perfect solution] If you have something that works perfectly for Newton's cradle, it will give a nonsense result for an impulse applied to a "frame" of mass 1 exactly enclosing a row ...
- Thu Oct 18, 2007 5:08 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Rope Physics in 2D
- Replies: 3
- Views: 11083
Re: Rope Physics in 2D
If all you need is rope stuff (and you don't need a full rigid body simulator), Verlet integration plus distance constraints by position projection is the simplest approach, and it's pretty fast. For each particle you store the current position and the last position, and time stepping is done as fol...
- Wed Oct 03, 2007 6:28 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Collision detection for mobile physics engine
- Replies: 6
- Views: 6928
Re: Collision detection for mobile physics engine
Figured I'd chime in here: I'm one of the people working on a port of Box2D to Java. Unfortunately at the moment we're not shooting for mobile Java yet, because a) we're still not sure how well things will run on regular old Java, and b) to use on mobile requires that all the math be converted to fi...
- Wed Oct 03, 2007 1:18 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: Rigid Body Techniques
- Replies: 7
- Views: 9859
Re: Rigid Body Techniques
Practically speaking, Verlet-based simulation is easy to understand, which makes it initially attractive, and there is something nice about having velocity-free representations (if you've ever done PDE simulations, wave equations or something like that, you'll know how much easier these can be to wo...
- Sat Sep 29, 2007 10:56 pm
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: 2d physics shape optimization
- Replies: 2
- Views: 3663
Re: 2d physics shape optimization
Probably not, is my opinion (others here definitely know more than I do, though). As far as I know, SAT is pretty much it for polygons, including triangles - you can't get much simpler than testing which side of a line something is on and by how much. The only caveat would be that you might be able ...
- Wed Sep 19, 2007 11:48 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Java physics engines?
- Replies: 7
- Views: 14564
Re: Java physics engines?
Alright, if I have the time I might see what I can accomplish here, probably with floating point at first - a Java port might be tricky to get running very fast, I'll have to take a look through and see whether there are things that could easily be changed to fix this (in particular object creation ...
- Tue Sep 11, 2007 11:07 pm
- Forum: General Bullet Physics Support and Feedback
- Topic: Java physics engines?
- Replies: 7
- Views: 14564
Re:
It seems to me that if you need to use physics within a Java program, you should be looking for a C/C++-based physics engine - and adding Java bindings to it so you can use it within Java code. That's not at all unreasonable since it keeps the heavy math in the C++ code and leaves you to do the hig...
- Wed Aug 29, 2007 1:07 am
- Forum: Research and development discussion about Collision Detection and Physics Simulation
- Topic: [solved] avoiding jitter with verlet rigid bodies
- Replies: 5
- Views: 7624