Fix collision shape bumps

max_godot

My conveyor is build out of multiple segments placed after each other

The gap between each segment is 0. When now my parcels (RigidBody3D) get moved along there is always a little bump when they move from one segment to the other.

Is there a way to smoothen this out so they just flow along without bumps?

Jesusemora

max_godot This might be another limitation of the godot engine, you can always just try Jolt.
But if you want to solve the problem, you have to make the conveyor a single collider.
There's a few ways I can think of:
1 - If you are not going to modify the conveyors, just replace their colliders with a single collider.
2 - if you need to modify the conveyors like in a minecraft or plate up, use a single collider that combines the sizes of the parts and changes size to fit in place. your individual conveyors could still have their own colliders for selection, but on a different layer. This collider would then change size when the conveyor is modified. But it needs to exist in some "manager" conveyor or some outside script that calculates and spawns the colliders needed for the scene.
3 - or simpler, when you put two conveyors they transform into a "size-2" conveyor, and 3 into a "size-3", etc. each being an object with a single collider. then treat them as a single object. some games do this, you can make the visual part different and it can even become part of the gameplay.
4 - It adds some fun movement to the rigidbodies, so unless it's causing some bug, I would leave it as it is.

I've said this many times before, but here it goes again: your physics and visuals are independent from each other. you can have a bunch of meshInstance3Ds, and then a single StaticBody3D containing all the colliders. Try to only use a different StaticBody when you need different physics interactions, like different layers or physics materials.

max_godot

Jesusemora thanks for the ideas!

Regarding option 2, how would I actually do that in GDScript? Is there a way that I can put all meshes in an array and say "magically merge it all to 1 and create a collision shape out of it"?

Jesusemora

max_godot sorry, I wrote 2 twice. it's fixed now.
for the first 2:
I think you can change the dimensions of a collider's BoxShape3D, at least in godot physics:
https://docs.godotengine.org/en/stable/classes/class_boxshape3d.html#class-boxshape3d
some tutorials make you change the collider dimensions, so it should work.

as for how, I would put the conveyors in a voxel/matrix so you can run an algorithm to find lines of conveyors, then spawn the colliders in a staticbody3D with the dimensions and in the positions where they have to collide. the colliders would be updated whenever a change is made, the easiest way would be to remove all colliders and spawn them again. If this is done one single time on a click, there shouldn't be much lag or at all. I did something like this but for road building, but I used bitmasks. This would be far more difficult.
put your voxel/matrix in an autoload for easy access and update it whenever a conveyor is created/destroyed.
This would involve changing the way your game is structured to something like in a city-builder, puzzle or RTS.
I have "pages" of code for doing this, it gets messy and complexity increases exponentially with every feature, you need a good grasp of math and algorithms. I don't recommend doing this just to get rid of a bump.

edit: for option 3:
when the conveyor is created, cast rays left and right of the conveyor. if it detects a conveyor of the same type, remove both and replace them with a double conveyor.
when a conveyor is spawned, like the double conveyor, it casts rays left and right, then it can detect other types of conveyors. if it detects one single conveyor, it removes it, self destructs and spawns a triple conveyor. if it detects two it turns into a 4-conveyor.
and so on with every combination. for a small game this would be enough or reduce the collisions enough.
It's better to calculate every combination beforehand and use a variable with a number to check for type. bitmasking is also useful here.