How to get or set body's final transform properly?

[donggas90]

Now I seeing dNewtonBody for wrapping.
but confusing to get or set body's final transform.
In 101 demo, using InterpolateMatrix to get position. and it's same with GetVisualMatrix.
BTW, what about GetMatrix? though it's faster then InterpolateMatrix, why demo does not use this?
and how about direct access dNewtonTransformLerp's members?
Thanks.

[JoeJ]

GetMatrix returns the real state of the body, the other functions do interpolation in case graphics update at another rate than physics.
Note that you should always run physics with a fixed timestep like 1/60 second.
But if graphics run somewhere between 40 and 80 fps, sometimes you need to do 2 or none physics steps per frame to sync to real time.
To compensate this and render smooth looking motion for physics bodies, you can interpolate / extrapolate or integrate the bodies to match framerate, and this is what those other functions do.

[donggas90]

Note that you should always run physics with a fixed timestep like 1/60 second.

Oh, I didn't know about that.

Thanks for reply.