Bullet Physics weird problem in Xcode + OSX

[gasim]

I have an undefined behavior in Bullet. Every time I leave the window or not touch anything for one minute; the step function gets called but no integration happens in that time. The physics system freezes while everything else gets updates (animation, input etc).

I am currently checking the timestep to see if thats the problem.

Please let me know if anyone had a problem like that before and how is it possible to solve it.

Thanks,
Gasim

[gasim]

The problem is on my timestep function. Now, need to find out how to fix it.

[Erwin Coumans]

Does it also happen in the unmodified Bullet 2.82 demos?

You might want to clamp the maximum delta time, if your computer was idle/sleeping, don't pass a huge value to delta time.

Code: Select all

int maxSimulationSubSteps = 10;
float fixedInternalTimeStep = 1./60.f;

world->stepSimulation(deltaTimeInSeconds, maxSimulationSubSteps, fixedInternalTimeStep);

This way, even if you pass a huge deltaTimeInSeconds, only 10 steps will be taken at maximum.

[gasim]

I don't quiet completely understand the time ticking thing. I will figure out some way to implement it correctly in my engine since I am updating my engine through abstract subsystems... But for now, passing a fixed value works ok. Thank you for the help!

[gasim]

My simulation stops when the object slowly stops moving. I don't understand why. Here is my main loop:

Code: Select all

float gameTime = 0.f;
        float timeAccumulator = 0.f;
        const float frameTime = 1.f/60.f;
        
        sf::Clock clock;
        while(mRunning) {
            float fTime = (clock.getElapsedTime().asMilliseconds())/1000.f;
            clock.restart();
            
            timeAccumulator += fTime;
            gameTime += fTime;
            
            mCurrentState->processInput();
            
            while(timeAccumulator >= frameTime) {
                mCurrentState->update(frameTime); // this is where the physics gets updated
                timeAccumulator -= frameTime;
            }
            
            mRenderWindow.clear();
            mRenderWindow.pushGLStates();
            mCurrentState->render();
            mRenderWindow.popGLStates();
            
            mRenderWindow.display();
        }

and in physics

Code: Select all

mWorld->stepSimulation(dt,10);

Is there anything else I should take into account here?

EDIT: Also, there is another problem I am facing. My object never stops moving. Whenever I key press it sets the linear velocity to Vector3(0,0,-1.5); and whenever key is released, the velocity becomes Vector3(0,0,0). but the object keeps moving. I am checking maybe the collision object is the problem.