voxel-physics-engine

Abstracted terrain physics for voxel game engines.

This implements reasonably realistic physics for voxel games. It was made to work with noa or voxel.js, but all it requires is abstracted (x,y,z) => boolean test functions for voxel properties, so it can be used with any engine.

This library replaces voxel-physical, though it works quite differently and behaves more physically. The engine can be seen in action in noa or projects using it.

Note: this simple engine only handles collisions between bodies and solid voxels. It does not handle collisions between rigid bodies, or non-cubic voxels.

Usage:

1. Create engine and supply a (x,y,z) => boolean functions that return whether a given voxel is solid or liquid.
2. Add rigid bodies with var body = addBody(..)
3. Modify body properties, or call its methods to apply forces, impulses, etc.
4. Call tick(dt) on the engine object

and the engine will update each body and handle voxel collisions.

Example

import { Physics } from 'voxel-physics-engine'
var opts = { gravity: [0, -10, 0] }
var voxelIsSolid = (x, y, z) => (y < 0)
var voxelIsLiquid = (x, y, z) => (x > 5)

var phys = new Physics(opts, voxelIsSolid, voxelIsLiquid)
var body = phys.addBody( aabb, mass, friction, restitution, gravityMult, onCollide )
phys.tick( dt_in_miliseconds )
phys.removeBody( body )

Features

• Reasonably physical, supports standard properties (friction, restitution, etc.)
• Query the body's resting[axis] property (-1,0,1 on each axis) to tell if it's currently touching a solid voxel. E.g. body.resting[1] is 1 when the body is colliding with the ceiling.
• Collisions with terrain trigger each body's onCollide(impacts) callback. The argument is a vec3 of the collision impulse on each axis. (A body resting on the ground will produce a small impact each tick due to gravity.)
• If you set a body's autoStep property, the engine will cause it to automatically "step" onto one-block obstructions.

Changes in latest version:

• 0.13.0 - minor fixes to typing and internals
• 0.11.0 - export a named constructor function instead of a callback
• 0.10.0
  • Fixes body.onCollide arg to be a correctly scaled impulse vector
  • Body onCollide now passed before bounces are resolved (allowing client to adjust body.restitution depending on the terrain)
• 0.9.0
  • Air and fluid friction properties renamed to airDrag and fluidDrag, and now work equivalently (no drag at 0, large drag at 1)
  • Per body airDrag and fluidDrag override global settings if >= 0
• 0.8.0
  • Friction now uses regular coefficients, and works in all directions, not just downwards
  • Bodies have an .airFriction that overrides the global value (if nonzero)
  • Air and regular friction should now scale correctly with frame rate