Physics - bounce on collision instead of sliding

[leovingi]

I've been playing around with Love2D physics over the last day, following the tutorial on the wiki. I'm trying to achieve bounce physics without any gravity or reduction in velocity, as in - when a ball hits a barrier at an angle it bounces off and keeps it's current velocity.

It works fine when the ball is approaching the barrier at a more direct angle, but if the angle is wide enough, the ball starts sliding instead.

How would I achieve a perfect bounce, without any sliding, even if the ball approaches a barrier at an angle of 1 degrees? Is it possible to change some of the Fixture (or any other) parameters? I've tried setting Friction to 1 for all objects, tried setting Friction to 0, but the outcome is the same - slide on a wide approach angle.

Simplified version of my current code attached

Code: Select all

Gamestate = {
    objects = {
        barrier = nil,
        ball = nil
    },
    world = nil
}

function love.load()
    math.randomseed(os.time())

    love.physics.setMeter(64)
    Gamestate.world = love.physics.newWorld(0, 0, true)

    Gamestate.objects.ball = {}
    Gamestate.objects.ball.body = love.physics.newBody(Gamestate.world, 650/2, 650/2, "dynamic")
    Gamestate.objects.ball.shape = love.physics.newCircleShape(10)
    Gamestate.objects.ball.fixture = love.physics.newFixture(Gamestate.objects.ball.body, Gamestate.objects.ball.shape, 0.1)
    Gamestate.objects.ball.fixture:setRestitution(1)
    Gamestate.objects.ball.fixture:setFriction(0)
    Gamestate.objects.ball.body:applyLinearImpulse(0, -0.7);

    Gamestate.objects.barrier = {
        body = love.physics.newBody(Gamestate.world, 650/2, 100, "static"),
        shape = love.physics.newRectangleShape(500, 20)
    }
    Gamestate.objects.barrier.fixture = love.physics.newFixture(Gamestate.objects.barrier.body, Gamestate.objects.barrier.shape)

    Gamestate.objects.barrier2 = {
        body = love.physics.newBody(Gamestate.world, 650/2, 550, "static"),
        shape = love.physics.newRectangleShape(500, 20)
    }
    Gamestate.objects.barrier2.fixture = love.physics.newFixture(Gamestate.objects.barrier2.body, Gamestate.objects.barrier2.shape)
    Gamestate.objects.barrier.fixture:setFriction(0)
    Gamestate.objects.barrier2.fixture:setFriction(0)

    love.window.setMode(650, 650)
end

function love.update(dt)
    Gamestate.world:update(dt)
end

function love.draw()
    love.graphics.print( love.timer.getFPS(), 10, 10 );

    love.graphics.setColor(0.76, 0.18, 0.05)
    love.graphics.circle("fill", Gamestate.objects.ball.body:getX(), Gamestate.objects.ball.body:getY(), Gamestate.objects.ball.shape:getRadius())

    love.graphics.setLineWidth(20)
    love.graphics.setLineStyle("smooth")
    love.graphics.setColor(1, 1, 1)
    love.graphics.line(Gamestate.objects.barrier.body:getX()-250, Gamestate.objects.barrier.body:getY(), Gamestate.objects.barrier.body:getX()+250, Gamestate.objects.barrier.body:getY())
    love.graphics.line(Gamestate.objects.barrier2.body:getX()-250, Gamestate.objects.barrier2.body:getY(), Gamestate.objects.barrier2.body:getX()+250, Gamestate.objects.barrier2.body:getY())
end

[pgimeno]

Thanks for the test code, but unfortunately it doesn't demonstrate the problem. This might be a box2d limitation, not sure until I see it. If so, you might need custom physics.

[idbrii]

You might be able to solve with World:setCallbacks.

See Tutorial:PhysicsCollisionCallbacks for details.