Temporarily turn off or disable bodies?

[grassgames]

Is there any way to temporarily disable or remove bodies so calls to NewtonUpdate() will ignore them?

I'm doing ball projectile deterministic calculations and I want to do them with just the ball and without the floor etc. involved - is this possible?

Thanks in advance...

[grassgames]

Further investigation reveals that NewtonMaterialSetDefaultCollidable() is what I want I think.

[Julio Jerez]

you can have a working world withe the object you want for the test.
basically you set it to the initial coditions and run the working work for predition.
The working world can have a small represention of what you are predicting, so you only need to reset it before start the prediction.

in fact you can place the working world in a separate thread so that predictions can be done asycronous with the simulation.

[grassgames]

Yes that works great and I have it implemented that way now - thanks.

I've noticed that I get a different projectile if using an Update of (1/60) compared to say an update of (1/500) - is this a problem with on my side, or expected behaviour ? Its seems the air friction or something is slowing the ball down more when a smaller Update amount is used.

[Julio Jerez]

different updates rate will produce differnat integration curves because numerical inetgration error are aproximation of exact integrations.
bu that is teh price we paid for solve diffrecacil equation numerically in a computer. the shorted the step the more acurate,

Se Numerical integration methods: Runge Kutta, and euler in wikipedia so that you have a better idea of why this happens.

[grassgames]

Ok - thanks for the info.