Is FixedJoint CANUSE?

[LLRukia]

I created a fixedjoint in my test program, and I give a speed (no matter linear or angular) to one of the rigid body of joint.
I can see it rotate totally irregular.

Then I review the code of SolveFixedJointSystem, I found a clerical error at line 457:
Vector3 w1 = mFixedJointComponents.mI2[i] * angularImpulseBody1;

I fixed it and try again, it behaves the same as before.

I am confused that does FixedJoint work well?

[DanielChappuis]

Hello. Thanks for your feedback.

I am not sure I understand your scenario. Can you please describe precisely what is your scenario, what behavior do you expect and what is happening ?

Then I review the code of SolveFixedJointSystem, I found a clerical error at line 457:
Vector3 w1 = mFixedJointComponents.mI2[i] * angularImpulseBody1;

Why do you think there is an error ? Can you please give some explanation ?

[LLRukia]

when we apply the impulse to rigid body 1, why using inertia tensor of body 2(mI2)?
Is it because of the impulse applied to each body is equal, then I think when changing angular speed should use inertia tensor of the body which is applying impulse.

I notice that the same position correction code in BallandSocketJoint, which use mI1 at line 366:
const Vector3 w1 = mBallAndSocketJointComponents.mI1[i] * angularImpulseBody1;

If there are any mistake, plz advise me.

[LLRukia]

I expect this behavior. This is a custom ball and socket joint rotation constraint. I think when the limit is violated, it behaves like a fixed joint.

[DanielChappuis]

Ok I see. Yes it's seems to be an error.

I have fixed this issue in the "issue_179" branch here. Could you try to pull this branch and see if it fixes the issue on your side ?

[LLRukia]

I found another error at FixedJointComponents.cpp, in function moveComponentToIndex:
new (mImpulseTranslation + destIndex) Vector3(mImpulseRotation[srcIndex]);
It should be new (mImpulseTranslation + destIndex) Vector3(mImpulseTranslation [srcIndex]);

[LLRukia]

And it seems to work well after we fix these 2 errors!

[DanielChappuis]

Perfect. I have pushed both fixes on the master branch.

Thanks a lot for your contribution.