MGilleronFJ
commented
1 month ago This is a known "issue" with this module due to how it is designed.
Assuming you turned on collisions, this can happen because unlike regular Godot nodes, terrains in that module use dynamic streaming systems and threads. When the Godot scene starts (after freezing the game until every node is added to the tree), terrain won't be ready immediately. Instead, it progressively loads chunks around the player, and keeps doing so as they move, without blocking the game. So your rigidbody will fall through it if you let it run immediately before chunks around it have reached a high-enough LOD level to have collision.
There are several ways to deal with that:
- Use a raycast down to find when ground starts becoming available
- Check if a small area around your player is loaded using VoxelTool.is_area_editable() (works best when using voxel box physics, less so when using Godot physics)
- Check if a small area around your player is meshed using VoxelLodTerrain.is_area_meshed
- Check if loading tasks are still ongoing by checking VoxelEngine.get_stats()
- Increase
collision_lod_countso lower LODs will also get a collider, so if terrain hasn't reached LOD0 when you hit it, there is a chance LOD1 will have generated. Though this can slow down loading a bit since there are more colliders to generate, and there can be some snags when LOD1 colliders switch to LOD0 colliders.
You can have an animated loading screen in the meantime, pause the game (except the terrain which needs to keep processing) or prevent the player from simulating until either of those conditions are fulfilled.
Note: if you managed to go through in that demo due to colliders not having generated in time, either you were moving way too fast, or your computer is too slow for the setup you have, because it's usually unlikely for colliders to still not be ready when you get close to them.
Given how high your body is, another possible issue is that you simply experienced collision tunnelling, which is also a known issue in generally every physics engine when using mesh colliders. Voxel terrain must use mesh colliders because it can have any concave shape. The downside is if your body is too small and moves too fast, it can go through a mesh collider surface if it never gets to intersect that surface: frame 1 is in front of the surface not intersecting, frame 2 is beyond the surface still not intersecting, therefore the physics engine doesn't detect the collision. This is not unique to voxels, it happens with mesh colliders in general.
Some fixes for tunneling would be:
- Cap your speed so it never becomes too high
- Make your collider bigger in the direction of movement
- Enable continuous collision detection, however it can be expensive and might not even be supported depending on which physics engine you're using
- If somehow you get inside terrain, you can query voxels around your character and if they are solid, teleport your player back to the last known position where it was not inside terrain
Note: in case you scaled your rigidbody, keep in mind this might not be well supported either, especially if you scaled it non-uniformly (it's not a box and your screen shows scaling gizmos so I suspect you did).
Finally, another simple cause is that you didn't have a VoxelViewer following your rigidbody.
In that demo, there is a VoxelViewer under the camera, which tells the voxel engine to load chunks around it. But if the rigidbody doesn't have one, then it's going to get far from the camera, where there won't be chunks with collision anymore, and yeah, it will go through them.
The streaming system is mostly player-centric, so you can't expect to have collision everywhere beyond some distance from the player, it would be way too expensive. Or the player would have to closely follow that falling box.
If you want a sharp collider everywhere you can see, then you pretty much have to forget about LOD and use VoxelTerrain.
If you really want to use VoxelLodTerrain and yet you really want bodies everywhere far from the player having collision with terrain, you could increase collision_lod_count so that more/every LOD has a collider, but they will snag when switching to higher/lower LODs as you move.
A heavier approach would be to put a VoxelViewer on these bodies, so the terrain loads around them too (which in itself also makes things more expensive). The default streaming system of VoxelLodTerrain doesn't support multiple VoxelViewers, but there is an experimental system you can enable by changing the streaming_system property to CLIPBOX. Then you may also need to turn off visuals for these extra viewers because I assume you won't need that.
That said, this feature is not well tested and might have issues. I'm not actively working on that area either at the moment so can't really help further there.
Sorry for the wall of text but as you can see with smooth voxel terrains with LOD and multi-threaded streaming, something that looks simple really isn't^^"
se8820726
Zylann
When applicable, please describe your setup:
i used Voxel game demos: https://github.com/Zylann/voxelgame/project/smooth_terrain/main.tcsn
then i made a rigidbody3d and a child collisionshape3d with default settings and when i played the scene the rigidbody went through the generated terrain and didnt stop on top of it. why ?