Search found 17 matches

by Apollo
Thu May 16, 2019 8:59 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

Yes, the values look better, and if it is working well for you then great! You have a good reference point now. You can make tuning deviations from there. Low angular damping is better. My advice: keep dialing it down until it is bad, then dial it back to where it was last good. Thank you for all o...
by Apollo
Thu May 16, 2019 8:14 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

Oops, I forgot to mention lowering the ball friction to something very low and then dialing it back up. It is good to have it lower than 0.9: a ball is smooth after all. If you adjusted the table's friction first before setting the ball to lower friction I would recommend going through the table tu...
by Apollo
Thu May 16, 2019 6:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

So I have adjusted the values to fit your recommendations, and I ended up back with the same issue of there being too large a difference when top spin was used. There was a difference between backspin and no-spin, but it was much smaller and seemed a lot more feasible. However, in changing these val...
by Apollo
Thu May 16, 2019 5:53 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

The fact that removing the table makes the divergence vanish means (I think) that the collision really is a 3-body interaction rather than a 2-body. The table acts as a momentum reservoir the the forces must balance at the time of collision. As such, I believe the effect is real and valid. Ignore t...
by Apollo
Wed May 15, 2019 8:31 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

Well... the ball is moving in the same direction in each case so if it hits at a different spot I would expect it to only be a vertical difference. For small balls I would expect a vertical variation to still produce horizontal deflection differences, but I don't have a good intuition for how much ...
by Apollo
Wed May 15, 2019 4:14 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

I had a thought about what could be causing it, and I wondered what you think about it, @drleviathan ... could the size of the balls be the cause of the angle difference? As in, because the balls are relatively small, the angle difference isn't actually that big, it just gives the perception of it b...
by Apollo
Wed May 15, 2019 3:48 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

Hrm... in the real world I would expect the spin on the cue to change the direction of the colored ball even when they collide in exactly the same spot. This is because both linear and angular momentum are conserved and the table is also involved. The balance of forces at the moment of impact will ...
by Apollo
Wed May 15, 2019 2:28 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Re: Unexplained behaviour with rigidbody applyImpulse

Could you provide some simple example? thanks. You say: ...the behaviour is completely unexpected. The direction of the object ball that was hit is completely different to the first two scenarios described All we know is that it is "different" but you don't otherwise describe it. It is difficult to...
by Apollo
Mon May 13, 2019 6:24 pm
Forum: General Bullet Physics Support and Feedback
Topic: Unexplained behaviour with rigidbody applyImpulse
Replies: 15
Views: 1335

Unexplained behaviour with rigidbody applyImpulse

Hi, I am trying to create a billiards/pool game, but am running into a problem with applying impulses to the spheres to simulate top spin. When I apply the impulse centrally (using applyCentralImpulse), there is no issue. Everything behaves as I would expect it to. When I use applyImpulse to simulat...
by Apollo
Fri Mar 15, 2019 1:49 pm
Forum: General Bullet Physics Support and Feedback
Topic: Strange Behaviour in Release Only
Replies: 6
Views: 878

Re: Strange Behaviour in Release Only

In preparing a small sample that demonstrates the issue, I managed to identify that the problem was related to the motionState. When creating the sample, I temporarily used a btDefaultMotionState instead, and when I ran the program using it the collider was identical to in release. I can't understan...
by Apollo
Fri Mar 15, 2019 7:38 am
Forum: General Bullet Physics Support and Feedback
Topic: Strange Behaviour in Release Only
Replies: 6
Views: 878

Re: Strange Behaviour in Release Only

steven wrote:
Fri Mar 15, 2019 1:23 am
Could you provide a simple test then i can work with you?
Yes that should be fine, I'll start working on a simple scene to upload as soon as possible. Thanks!
by Apollo
Thu Mar 14, 2019 9:38 pm
Forum: General Bullet Physics Support and Feedback
Topic: Strange Behaviour in Release Only
Replies: 6
Views: 878

Strange Behaviour in Release Only

Hi, When I run my game in Debug in Visual Studio, all of the physics work perfectly. When I run it in Release, however, the collision shapes are completely wrong and therefore physics doesn't work as intended. There are no errors however when running in release so I'm unsure as to how to debug what'...
by Apollo
Mon Feb 13, 2017 12:18 pm
Forum: General Bullet Physics Support and Feedback
Topic: Framerate Independence Issue
Replies: 4
Views: 1679

Re: Framerate Independence Issue

This might provide a good place to start. Its got a good amount of info on getting your applicaiton to be framerate independent (something Skyrim can't boast about!) http://www.bulletphysics.org/mediawiki-1.5.8/index.php?title=Canonical_Game_Loop This worked really well, thank you to everyone for t...
by Apollo
Fri Feb 03, 2017 3:20 pm
Forum: General Bullet Physics Support and Feedback
Topic: Framerate Independence Issue
Replies: 4
Views: 1679

Framerate Independence Issue

Hi, We are trying to make our game framerate independent, but are currently having issues with it. We tried reading previous threads on the subject but haven't managed to solve it. We've tried using a fixed timestep as well as a variable timestep, with neither working. We're currently testing on two...
by Apollo
Wed Jan 18, 2017 1:21 pm
Forum: General Bullet Physics Support and Feedback
Topic: btConvexHullShape questions
Replies: 3
Views: 1515

Re: btConvexHullShape questions

The point of a convex hull is to roughly approximate a mesh. If you are looking for more precise mesh collisions then I would consider using btGImpactMeshShape if your model is concave, or you could also use the HACD algorithm in bullet to generate a more accurate representation of your 3D model. I...