Expose get_debug_mesh in Shape3D to scripting API

[pouleyKetchoupp]

Can be useful for custom drawing of physics shapes without having to add a collision object node to the tree.

Avoids hacks like this one (in this case, drawing a shape used in a query, not attached to a node):
https://github.com/godotengine/godot-demo-projects/blob/2ce76ff4e5abfa352a5bca4de9b1214567579b8d/3d/physics_tests/test.gd#L48-L70

Can be replaced with:

func add_shape(shape, transform, color):
	var debug_mesh = shape.get_debug_mesh()
	
	var mesh_instance = MeshInstance.new()
	mesh_instance.transform = transform
	mesh_instance.mesh = debug_mesh
	
	var material = SpatialMaterial.new()
	material.flags_unshaded = true
	material.albedo_color = color
	mesh_instance.material_override = material
	
	add_child(mesh_instance)
	_drawn_nodes.push_back(mesh_instance)

This change will also be needed after #48175 is merged, since the debug mesh node won't be available anymore.

[akien-mga]

Thanks!

[Zireael07]

Wait... am I reading this right that this will let me draw debug stuff (areas/collisions) in DIFFERENT colors? YAAAY!

[pouleyKetchoupp]

Wait... am I reading this right that this will let me draw debug stuff (areas/collisions) in DIFFERENT colors? YAAAY!

Yes, that's one of the possibilities, along with any kind of rendering options :)
Although custom debug color will be probably just added as a property in the future since it's very useful for debugging.

[Zireael07]

@pouleyKetchoupp: Please please do (remember, I have a proposal open about customizing colors for debug shapes)

[Calinou]

@pouleyKetchoupp: Please please do (remember, I have a proposal open about customizing colors for debug shapes)

There's already a PR and proposal for it: #40123 - godotengine/godot-proposals#906

It's only for 3D though – a separate PR would have to be made for 2D.