Add force step method to physics

[RevenantX]

This method helps implementing best network FPS physics.

[akien-mga]

CC @AndreaCatania

[pgruenbacher]

I don't follow the justification?

My guess is that instead of server.set_active(true); server.step(); server.set_active(false); you can do server.force_step() is what you want...

except the bound method step for the physics server has been commented ever since its open-source inception, so I'm guessing there's a reason step isn't being allowed to be called as a bound method.... and that reason would also apply to the force step...

[reduz]

I dont really understand how this would be used

[RevenantX]

@pgruenbacher i tested this code and it works well.
@reduz like in unity3d - there is Physics.Simulate method. Very usable for client side prediction (you can freeze or rewind all physical objects and then resimulate some number of frames at one time)

[AndreaCatania]

This could be useful but not in that way. When you need to sync physics you have to instantiate more then one physics space and "step" only it when necessary.

In the way you implemented it, the force step will force the processing of all spaces and not a particular one, and this is always wrong.

[RevenantX]

@AndreaCatania you can deactivate spaces before step. (or deactivate some bodies).
In many FPS games there is no much physics. Only on projectiles and players. So there is no sense add more "spaces" than one. You can just disable objects before step or make them kinematic (or rewind all states).
Look at https://docs.unity3d.com/ScriptReference/Physics.Simulate.html

[AndreaCatania]

I don't know unity, but this is really depend on the kind of project and approach. But from Godot side advance all spaces all together has no sense.

So I would add an API that accept the space RID to be stepped.

[RevenantX]

@AndreaCatania well thats usefull for my purposes too.

[AndreaCatania]

@RevenantX why did you close it?

[RevenantX]

@AndreaCatania because better will be create another pull request with "space" step?

[AndreaCatania]

Usually we change the current commit, to keep a track of discussion. But it's not a problem do it in the way you are more comfortable.