Voxel Collision

This page details how collision works for voxel objects in Voxel Playground, including setup, penetration mechanics, and advanced configuration.

1. Voxel Object Collision Setup

For most voxel objects, you should use the VoxelObjectProxy component.

• It automatically handles mesh generation and collision setup.
• You do not need to manually add collision components; VoxelObjectProxy takes care of it.

2. Penetration Mechanics

Voxel Playground uses a custom physics to simulate object penetration based on material hardness and velocity. This allows harder objects to penetrate softer ones (e.g., a metal ball going through wood, or a car crashing through a brick wall).

The system compares the Hardness of the two colliding objects (see Material ID and Visual for hardness values).

1. Hardness Check: The system calculates the difference in hardness between the two objects.
   • If the difference is small, standard physics apply (objects bounce or stop).
   • If the difference is significant, the system calculates a "decay" factor. In this scenario, the relative velocity of the two objects is not resolved to zero, so they continue to move and penetrate each other.
2. Velocity Check:
   • Generally, higher relative velocity enables deeper/easier penetration.
3. Resolution:
   • The "Harder" object penetrates the "Softer" object.
   • The "Softer" object offers resistance based on the hardness difference.
   • Indestructible objects are protected from penetration unless specific conditions are met.

3. Voxel Object Types & Auto-Configuration

When using VoxelObjectProxy, the VoxelObjectProxyType determines how the underlying components (VoxelVolume, PxVoxelColliderGenerator, VoxelDestructor) are configured. You usually don't need to touch these manually.

Here is a summary of how different types configure the object:

• Connectivity Check: Whether the object checks if parts of it are floating/disconnected (and should fall off).
• Chemistry Effect: Whether the voxel chemetry simulation updates (fire, water, poison).
• Layer: The Unity/Physics layer assigned (Item vs Building).
• Destructible: Controlled by VoxelDestructor. SceneStatic is generally set to Indestructible.