Physics Ball

Questions
1

Query: I have a physics ball to be hit by two paddles (comprised of other physics balls) (think air hockey), however, when the ball is hit, it moves, but does not slide like a normal ball. Thought so is probably because I am not very experienced in the field of physics coding, and am missing some necessary code. Would it be possible to add code to the ball to make it slide while having no additional code applied to the paddles? If not, what would be the best alternative way to make the ball slide?

-- variables for various functions and positions
    -- ballpos = vector 2 starting position of the ball
    -- pos1 = vector 2 constant position of Player 1's paddle
    -- pos2 = vector 2 constant position of Player 2's paddle
    
function setup()
    -- Ball
    ball = physics.body(CIRCLE,25)
    ball.type = DYNAMIC
    ball.position = ballpos
    ball.gravityScale = 0
    ball.sleepingAllowed = false

    -- Player 1's Paddle
    Player1 = physics.body(CIRCLE,50)
    Player1.type = KINEMATIC
    Player1.position = pos1
    Player1.gravityScale = 0
    Player1.sleepingAllowed = false

    -- Player 2's Paddle
    Player2 = physics.body(CIRCLE,50)
    Player2.type = KINEMATIC
    Player2.position = pos2
    Player2.gravityScale = 0
    Player2.sleepingAllowed = false

end


function draw()

    -- Ball
    ballpos = ball.position
    strokeWidth(0)
    fill(255, 255, 255, 255)
    ellipse(ball.position.x,ball.position.y,25)
        
    -- Player 1
    pos1.x = math.max(70,pos1.x)
    pos1.x = math.min(WIDTH-70,pos1.x)
    pos1.y = math.max(70,pos1.y)
    pos1.y = math.min(HEIGHT/2-50,pos1.y)
    Player1.position = pos1
    strokeWidth(30)
    stroke(255,0,0,255)
    fill(0, 0, 0, 255)
    ellipse(Player1.position.x, Player1.position.y, 50)
        
    -- Player 2
    pos2.x = math.max(70,pos2.x)
    pos2.x = math.min(WIDTH-70,pos2.x)
    pos2.y = math.max(HEIGHT/2+50,pos2.y)
    pos2.y = math.min(HEIGHT-70,pos2.y)
    Player2.position = pos2
    strokeWidth(30)
    stroke(0,255,255,255)
    fill(0, 0, 0, 255)
    ellipse(Player2.position.x, Player2.position.y, 50)

end
2

@CayDay47 Here’s your code modified for what I think you’re after.


displayMode(FULLSCREEN)

function setup()
    et=physics.body(EDGE,vec2(0,HEIGHT),vec2(WIDTH,HEIGHT))
    eb=physics.body(EDGE,vec2(0,0),vec2(WIDTH,0))

    -- Ball
    ball = physics.body(CIRCLE,25)
    ball.position = vec2(WIDTH/2,HEIGHT/2)
    ball.gravityScale=0
    ball.sleepingAllowed = false
    ball.restitution=.8
    ball.linearVelocity=vec2(-300,300)

    -- Player 1's Paddle
    Player1 = physics.body(CIRCLE,50)
    Player1.position = vec2(50,HEIGHT/2)
    Player1.sleepingAllowed = false
    Player1.type=KINEMATIC

    -- Player 2's Paddle
    Player2 = physics.body(CIRCLE,50)
    Player2.position = vec2(WIDTH-50,HEIGHT/2)
    Player2.sleepingAllowed = false
    Player2.type=KINEMATIC
end


function draw()
    background(0)
    stroke(255)
    strokeWidth(2)
    line(0,0,WIDTH,0)
    line(0,HEIGHT,WIDTH,HEIGHT)
    line(WIDTH/2,0,WIDTH/2,HEIGHT)
    
    noStroke()
    -- Ball
    fill(255, 255, 255, 255)
    ellipse(ball.x,ball.y,50)

    -- Player 1
    fill(0, 10, 255, 255)
    ellipse(Player1.x, Player1.y,100)

    -- Player 2
    fill(61, 255, 0, 255)
    ellipse(Player2.x, Player2.y,100)
end

function touched(t)
    if t.state==BEGAN then
        if t.x<WIDTH/2 then
            Player1.position=vec2(t.x,t.y)
            id1=t.id
        else
            Player2.position=vec2(t.x,t.y)
            id2=t.id
        end        
    end
    if t.state==MOVING then
        if t.id==id1 then
            Player1.linearVelocity=vec2(t.deltaX*65,t.deltaY*65)
        end
        if t.id==id2 then
            Player2.linearVelocity=vec2(t.deltaX*65,t.deltaY*65)
        end
    end
    if t.state==ENDED then
        if t.id==id1 then
            id1=0
            Player1.linearVelocity=vec2(0,0)
        end
        if t.id==id2 then
            id2=0 
            Player2.linearVelocity=vec2(0,0)
        end        
    end
end
3

Thanks for the basics in physics, however, is there a way to simulate the linear velocity with the variables from my original version, pos1 and pos2?
The reason being that I am not moving the paddles based on the exact area of my touch. Instead, there will be another way of control which will give me the vec2 of pos1 and pos2.

4

@CayDay47 To properly move a physics object, you need to use linearVelocity. You can still move a physics object without using linearVelocity, but while it’s being moved it’s ignoring some of its physics properties. It’s interaction with other physics objects won’t work the way it should. Since I don’t know exactly how you’re planning to use pos1 and pos2, I would just be guessing at how to change the code.

5

@dave1707 The way Pos1 and Pos2 work is that they recieve a vec2 from a controller style input(think joystick) before forawrding the vec2 forward to the physics balls. The controllers rely on a position and change of touch, meaning that the code you sent me may not have to move from the touched function.
Because I saw you used the deltaX and deltaY on touch, maybe a deltaX and deltaY could be facilitated for Pos1 and Pos2, maning that the majority of the same code could be used.

6

@CayDay47 Here’s what I think you’re asking for with pos1 and pos2. I also extende the top and bottom lines to go up and down the sides.


displayMode(FULLSCREEN)
supportedOrientations(LANDSCAPE_ANY)

function setup()
    physics.continuous=true
    pos1=vec2(0,0)
    pos2=vec2(0,0)
        et=physics.body(CHAIN,false,vec2(0,HEIGHT-250),vec2(0,HEIGHT),vec2(WIDTH,HEIGHT),vec2(WIDTH,HEIGHT-250))
    eb=physics.body(CHAIN,false,vec2(0,250),vec2(0,0),vec2(WIDTH,0),vec2(WIDTH,250))

    -- Ball
    ball = physics.body(CIRCLE,25)
    ball.position = vec2(WIDTH/2,HEIGHT/2)
    ball.gravityScale=0
    ball.sleepingAllowed = false
    ball.restitution=.8
    ball.bullet=true
    ball.linearVelocity=vec2(math.random(300,500),math.random(300,500))

    -- Player 1's Paddle
    Player1 = physics.body(CIRCLE,50)
    Player1.position = vec2(50,HEIGHT/2)
    Player1.sleepingAllowed = false
    Player1.type=KINEMATIC

    -- Player 2's Paddle
    Player2 = physics.body(CIRCLE,50)
    Player2.position = vec2(WIDTH-50,HEIGHT/2)
    Player2.sleepingAllowed = false
    Player2.type=KINEMATIC
end

function draw()
    background(0)
    stroke(255)
    strokeWidth(2)
    line(WIDTH/2,0,WIDTH/2,HEIGHT)
    
    line(0,HEIGHT-250,0,HEIGHT)
    line(0,HEIGHT,WIDTH,HEIGHT)
    line(WIDTH,HEIGHT,WIDTH,HEIGHT-250)
    
    line(0,250,0,0)
    line(0,0,WIDTH,0)
    line(WIDTH,0,WIDTH,250)
    
    noStroke()
    -- Ball
    fill(255, 255, 255, 255)
    ellipse(ball.x,ball.y,50)

    -- Player 1
    fill(0, 10, 255, 255)
    Player1.linearVelocity=pos1
    ellipse(Player1.x, Player1.y,100)

    -- Player 2
    fill(61, 255, 0, 255)
    Player2.linearVelocity=pos2
    ellipse(Player2.x, Player2.y,100)
end

function touched(t)
    if t.state==BEGAN then
        if t.x<WIDTH/2 then
            pos1=vec2(0,0)
            id1=t.id
        else
            pos2=vec2(0,0)
            id2=t.id
        end        
    end
    if t.state==MOVING then
        if t.id==id1 then
            pos1=vec2(t.deltaX*60,t.deltaY*60)
        end
        if t.id==id2 then
            pos2=vec2(t.deltaX*60,t.deltaY*60)
        end
    end
    if t.state==ENDED then
        if t.id==id1 then
            id1=0
            pos1=vec2(0,0)
        end
        if t.id==id2 then
            id2=0 
            pos2=vec2(0,0)
        end        
    end
end
7

Thats alright, I already have a border, the code I sent you was taken out of the full project and simplified.