File:raycast example screenshot.png

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

	World = love.physics.newWorld()

	Box = {}
	Box.Body = love.physics.newBody(World, 400, 300, "dynamic")
	Box.Shape = love.physics.newRectangleShape(150, 150)
	Box.Fixture = love.physics.newFixture(Box.Body, Box.Shape)

	-- Giving the box a gentle spin.
	Box.Body:setAngularVelocity(0.5)

	Ray1 = {
		point1 = {},
		point2 = {},
	}
	Ray1.point1.x, Ray1.point1.y = 50, 50
	Ray1.point2.x, Ray1.point2.y = 400, 300
	Ray1.scale = 1

	Ray2 = {
		point1 = {},
		point2 = {},
	}
	Ray2.point1.x, Ray2.point1.y = 500, 400
	Ray2.point2.x, Ray2.point2.y = Ray2.point1.x + math.cos(math.pi*1.45), Ray2.point1.y + math.sin(math.pi*1.45)
	Ray2.scale = 150
end

function love.update(dt)
	World:update(dt)
end

function love.draw()
	-- Drawing the box.
	love.graphics.setColor(255, 255, 255)
	love.graphics.polygon("line", Box.Body:getWorldPoints( Box.Shape:getPoints() ))

	-- Drawing the input lines of the rays and the reach of ray 2 in gray.
	love.graphics.setLineWidth(3)
	love.graphics.setColor(50, 50, 50)
	love.graphics.line(Ray2.point1.x, Ray2.point1.y, Ray2.point1.x + (Ray2.point2.x - Ray2.point1.x) * Ray2.scale, Ray2.point1.y + (Ray2.point2.y - Ray2.point1.y) * Ray2.scale)
	love.graphics.setColor(255, 255, 255)
	love.graphics.line(Ray1.point1.x, Ray1.point1.y, Ray1.point2.x, Ray1.point2.y)
	love.graphics.line(Ray2.point1.x, Ray2.point1.y, Ray2.point2.x, Ray2.point2.y)
	love.graphics.setLineWidth(1)

	-- Remember that the ray cast can return nil if it hits nothing.
	local r1nx, r1ny, r1f = Box.Fixture:rayCast(Ray1.point1.x, Ray1.point1.y, Ray1.point2.x, Ray1.point2.y, Ray1.scale)
	local r2nx, r2ny, r2f = Box.Fixture:rayCast(Ray2.point1.x, Ray2.point1.y, Ray2.point2.x, Ray2.point2.y, Ray2.scale)

	if r1nx then
		-- Calculating the world position where the ray hit.
		local r1HitX = Ray1.point1.x + (Ray1.point2.x - Ray1.point1.x) * r1f
		local r1HitY = Ray1.point1.y + (Ray1.point2.y - Ray1.point1.y) * r1f

		-- Drawing the ray from the starting point to the position on the shape.
		love.graphics.setColor(255, 0, 0)
		love.graphics.line(Ray1.point1.x, Ray1.point1.y, r1HitX, r1HitY)

		-- We also get the surface normal of the edge the ray hit. Here drawn in green
		love.graphics.setColor(0, 255, 0)
		love.graphics.line(r1HitX, r1HitY, r1HitX + r1nx * 25, r1HitY + r1ny * 25)
	end

	if r2nx then
		-- Calculating the world position where the ray hit.
		local r2HitX = Ray2.point1.x + (Ray2.point2.x - Ray2.point1.x) * r2f
		local r2HitY = Ray2.point1.y + (Ray2.point2.y - Ray2.point1.y) * r2f

		-- Drawing the ray from the starting point to the position on the shape.
		love.graphics.setColor(255, 0, 0)
		love.graphics.line(Ray2.point1.x, Ray2.point1.y, r2HitX, r2HitY)

		-- We also get the surface normal of the edge the ray hit. Here drawn in green
		love.graphics.setColor(0, 255, 0)
		love.graphics.line(r2HitX, r2HitY, r2HitX + r2nx * 25, r2HitY + r2ny * 25)
	end
end