World:rayCast

function callback(fixture, x, y, xn, yn, fraction)
    return 1
end

World:rayCast( x1, y1, x2, y2, callback )

function worldRayCastCallback(fixture, x, y, xn, yn, fraction)
    local hit = {}
    hit.fixture = fixture
    hit.x, hit.y = x, y
    hit.xn, hit.yn = xn, yn
    hit.fraction = fraction

    table.insert(Ray.hitList, hit)

    return 1 -- Continues with ray cast through all shapes.
end

function createStuff()
    -- Cleaning up the previous stuff.
    for i = 1, #Terrain.Stuff do
        Terrain.Stuff[i].Fixture:destroy()
        Terrain.Stuff[i] = nil
    end

    -- Generates some random shapes.
    for i = 1, 30 do
        local p = {}

        p.x, p.y = math.random(100, 700), math.random(100, 500)
        local shapetype = math.random(3)
        if shapetype == 1 then
            local w, h, r = math.random() * 10 + 40, math.random() * 10 + 40, math.random() * math.pi * 2
            p.Shape = love.physics.newRectangleShape(p.x, p.y, w, h, r)
        elseif shapetype == 2 then
            local a = math.random() * math.pi * 2
            local x2, y2 = p.x + math.cos(a) * (math.random() * 30 + 20), p.y + math.sin(a) * (math.random() * 30 + 20)
            p.Shape = love.physics.newEdgeShape(p.x, p.y, x2, y2)
        else
            local r = math.random() * 40 + 10
            p.Shape = love.physics.newCircleShape(p.x, p.y, r)
        end

        p.Fixture = love.physics.newFixture(Terrain.Body, p.Shape)

        Terrain.Stuff[i] = p
    end
end

function love.keypressed()
    createStuff()
end

function love.load()
    -- Setting this to 1 to avoid all current scaling bugs.
    love.physics.setMeter(1)

    -- Start out with the same random stuff each start.
    math.randomseed(0xfacef00d)

    World = love.physics.newWorld()

    Terrain = {}
    Terrain.Body = love.physics.newBody(World, 0, 0, "static")
    Terrain.Stuff = {}
    createStuff()

    Ray = {
        x1 = 0,
        y1 = 0,
        x2 = 0,
        y2 = 0,
        hitList = {}
    }
end

function love.update(dt)
    local now = love.timer.getMicroTime()

    World:update(dt)

    -- Clear fixture hit list.
    Ray.hitList = {}
   
    -- Calculate ray position.
    local pos = (math.sin(now/4) + 1.2) * 0.4
    Ray.x2, Ray.y2 = math.cos(pos * (math.pi/2)) * 1000, math.sin(pos * (math.pi/2)) * 1000
   
    -- Cast the ray and populate the hitList table.
    World:rayCast(Ray.x1, Ray.y1, Ray.x2, Ray.y2, worldRayCastCallback)
end

function love.draw()
    -- Drawing the terrain.
    love.graphics.setColor(255, 255, 255)
    for i = 1, #Terrain.Stuff do
        if Terrain.Stuff[i].Shape:getType() == "polygon" then
            love.graphics.polygon("line", Terrain.Body:getWorldPoints( Terrain.Stuff[i].Shape:getPoints() ))
        elseif Terrain.Stuff[i].Shape:getType() == "edge" then
            love.graphics.line(Terrain.Body:getWorldPoints( Terrain.Stuff[i].Shape:getPoints() ))
        else
            local x, y = Terrain.Body:getWorldPoints(Terrain.Stuff[i].x, Terrain.Stuff[i].y)
            love.graphics.circle("line", x, y, Terrain.Stuff[i].Shape:getRadius())
        end
    end

    -- Drawing the ray.
    love.graphics.setLineWidth(3)
    love.graphics.setColor(255, 255, 255, 100)
    love.graphics.line(Ray.x1, Ray.y1, Ray.x2, Ray.y2)
    love.graphics.setLineWidth(1)

    -- Drawing the intersection points and normal vectors if there were any.
    for i = 1, #Ray.hitList do
        local hit = Ray.hitList[i]
        love.graphics.setColor(255, 0, 0)
        love.graphics.print(i, hit.x, hit.y) -- Prints the hit order besides the point.
        love.graphics.circle("line", hit.x, hit.y, 3)
        love.graphics.setColor(0, 255, 0)
        love.graphics.line(hit.x, hit.y, hit.x + hit.xn * 25, hit.y + hit.yn * 25)
    end
end