HC - General purpose collision detection with LÖVE

HC is a Lua module to simplify one important aspect in computer games: Collision detection.

It can detect collisions between arbitrary positioned and rotated shapes. Built-in shapes are points, circles and polygons. Any non-intersecting polygons are supported, even concave ones. You can add other types of shapes if you need them.

The main interface is simple:

  1. Set up your scene,
  2. Check for collisions,
  3. React to collisions.

First steps

This is an example on how to use HC. One shape will stick to the mouse position, while the other will stay in the same place:

HC = require 'HC'

-- array to hold collision messages
local text = {}

function love.load()
    -- add a rectangle to the scene
    rect = HC.rectangle(200,400,400,20)

    -- add a circle to the scene
    mouse = HC.circle(400,300,20)

function love.update(dt)
    -- move circle to mouse position

    -- rotate rectangle

    -- check for collisions
    for shape, delta in pairs(HC.collisions(mouse)) do
        text[#text+1] = string.format("Colliding. Separating vector = (%s,%s)",
                                      delta.x, delta.y)

    while #text > 40 do
        table.remove(text, 1)

function love.draw()
    -- print messages
    for i = 1,#text do
        love.graphics.setColor(255,255,255, 255 - (i-1) * 6)
        love.graphics.print(text[#text - (i-1)], 10, i * 15)

    -- shapes can be drawn to the screen

Get HC

You can download the latest packaged version as zip- or tar-archive directly from github.

You can also have a look at the sourcecode online here.

If you use the Git command line client, you can clone the repository by running:

git clone git://github.com/vrld/HC.git

Once done, you can check for updates by running:

git pull

from inside the directory.