Improved Physics Queries

[cmann1]

I know there are a few different discussions/issues which touch on this, but feel like they're all sort of part of the same problem, and hasn't really been addressed fully yet.

So for really basic functionality, or using the built in nodes, querying the world is simple enough, but if you need to manually do anything more advanced than that, it becomes a lot harder/cumbersome to use.

I'm also comparing this to Unity which has a lot more functionality, and what it does have is much simpler to use.

As I see it there are four major problems it at the moment:

1. Missing really basic common functionality.

• ray_cast, and closest_point - methods for individual colliders.
• ray_cast_all, motion_cast_all, overlap_all - for space states.
• compute_penetration - calculates the distance and direction two colliders are overlapping.

2. Existing functions are way more complex and unintuitive than they should be.

Primarily this is referring to cast_motion and get_rest_info.
There's no reason for it being this complex - there should really be a single sweep_shape which returns the distance and collision results in a single call.
This also overlaps with point 1. - XXX_all variants of the raycast and overlap methods would be a lot less clunky (and possibly more performant) than looping and updating the exclude property.

3. Return values.

I know there are some issues about adding struct support to gdscript, though I don't know if or when this would be implemented.
But basically dictionaries are just awkward to use, and some sort of HitResult object with appropriate properties would be much more convenient.

4. Inaccurate motion_cast.

As far as I can tell the current method is just an approximation that steps the shape through the scene at some fixed resolution until an overlap is found.
I don't know how complex/possible it would be for arbitrary collision shapes, but for basic geometric shapes such as circles/spheres etc. surely this could be done mathematically, which would be 100% accurate, and possibly more performant.

[DinkeyKing]

Another method I miss from physics queries is one that returns shape rest info from multiple contacts. PhysicsDirectSpaceState.get_rest_info is arbitrarily limited to return only one contact's info, and is also missing the contact depth. I have a proposal (#11609) and a PR (godotengine/godot#101676) ready for adding this missing shape query method.

As far as I can tell the current method is just an approximation that steps the shape through the scene at some fixed resolution until an overlap is found.

Adding a sweep test to PhysicsDirectSpaceState3D would result in a shape cast that is more accurate and performant than the current binary search. There is currently no proposal for this yet. I might try tackling this.

But basically dictionaries are just awkward to use, and some sort of HitResult object with appropriate properties would be much more convenient.

Changing the return types of the current queries would be a breaking change, my guess is that (sadly) this may only happen in the far future (Godot 5).

[cmann1]

I have a proposal (#11609) and a PR (godotengine/godot#101676) ready for adding this missing shape query method.

Nice. I'm not sure what it takes for a PR to be accepted, but hopefully this one goes through soon.