raycast-2d-tilemap

raycast-2d-tilemap

Test a ray for intersections against a 2D tile map.

Background

This module is built atop the excellent fast-voxel-raycast by Andy Hall, which in turn is a fork of Mikola Lysenko's wonderful voxel-raycast.

Both are 3D voxel modules -- this module just wraps Andy's work to provide a clean 2D interface.

Installation

npm install raycast-2d-tilemap

Example

var raycast = require('raycast-2d-tilemap')

var tilemap = [
    [ 0, 0, 0, 1 ],
    [ 1, 0, 0, 1 ],
    [ 1, 0, 0, 1 ],
    [ 1, 1, 1, 1 ]
]

function getTileAt(x, y) {
  return tilemap[y][x]
}

var rayStart = [1, 0]
var rayDir = [0, 1]
var maxDistance = 100

var hitPos = new Array(2)
var hitNormal = new Array(2)

var tile = raycast(getTileAt, rayStart, rayDir, maxDistance, hitPos, hitNormal)

console.log(hitPos)
console.log(hitNormal)

outputs

[ 1, 3 ]
[ 0, -1 ]

Usage

var raycast = require('raycast-2d-tilemap')

var tile = raycast(getTileAt, rayStart, rayDir, maxDistance, hitPos, hitNormal)

• getTileAt - a function(x, y) that returns a truthy value for whether a tile should block the ray's path
• rayStart - origin of the ray (vec2)
• rayDirection - direction of the ray (vec2)
• maxDistance - how far to check the ray before giving up
• hitPosition - result vec2 array; populated with the point of impact
• hitNormal - result vec2 array; populated with a normal vector pointing away from the tile that was struck

Returns: whatever value was returned by the getTileAt function for the struck tile, or 0 if no tile was struck.