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I'm creating a voxel-based game with procedurally generates rooms. I've created a 'voxel-no-collision' scene which just contains a single MeshInstance node, and elsewhere a 'room generator' script instances this scene and then uses a SurfaceTool to build the appropriate cube faces. Without any collision involved everything runs at a reasonable speed. However, when I have the room generator instance a different 'voxel' scene which is identical except it also contains a StaticBody and CollisionShape (which has a default BoxShape and a scale of 0.5, 0.5, 0.5) the level generation becomes very very slow.

As a point of reference, I instantiated a 20x20x20 grid of cubes without collision and it takes on average about 125ms to complete, but with collision it takes on average 5 seconds (i.e. with collision it is 4,000% slower!)

For comparison, I set up the same process in Unity (spawning a 20x20x20 grid of Cube Prefabs - both with and without a BoxCollider). Without collision involved the instancing speed was very similar to Godot (around 125ms), however the addition of a BoxCollider to the prefab had a far smaller impact. The total time to instance all 8,000 'cubes with collision' increased to just 200ms - so only 60% slower which is a lot better that the 4,000% slow-down that I'm seeing in Godot.

Could anyone please explain the cause of the delay that I'm seeing, and let me know if there is a different approach that I could take in Godot to achieve similar speeds?

Thanks in advance.

asked Feb 1, 2019 in Engine by cakemonitor (53 points)
retagged Feb 2, 2019 by cakemonitor

1 Answer

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This is a known issue since the migration to Bullet, see this GitHub issue. Try switching to Godot physics in the Project Settings and see if performance improves.

answered Feb 2, 2019 by Calinou (5,674 points)
selected Feb 3, 2019 by cakemonitor

Thanks! It's about 5 times faster with Godot Physics, but I get other errors and my character no longer moves. But I made a few optimisations in terms of how many colliders I need and I can probably design around other performance issues for now, so I'll stick with Bullet.

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