Collisions

Questions
1

Whenever I make two physics bodies and have the collide(c) function with an output print “collision” it spams the output with the statement and crashes the app. help!? thanks in advance!

2

Remove the print statement?..

3

no the problem is that it is detecting a collision even when the bodies are way apart from each other. Sorry i was unclear.

4

@compactbear it would be usefull if you posted the code you use, so we can determine what’s wrong…

5

Yup, without the code it’s difficult to give any further help…but are you calling the collide function from draw? If so, there is no need to explicitly do this as collide will be called automatically when two bodies collide.

I’ve an example in my cook off code (though am sure that this isn’t the best way to do it, but it works!)

https://gist.github.com/Westenburg/8139969

6

@compactbear Here’s some code. Compare this to yours


function setup() 
    c1 = physics.body(CIRCLE,100)    -- create body for 1st circle
    c1.type=STATIC
    c1.x=WIDTH/2
    c1.y=300
    
    c2 = physics.body(CIRCLE,50)    -- create body for 2nd circle
    c2.x=WIDTH/2
    c2.y=800
    c2.restitution=1
end

function draw()
    background(40,40,50)
    stroke(255)
    strokeWidth(1)
    noFill()
    ellipse(c1.x,c1.y,200,200)    -- draw the 1st circle
    ellipse(c2.x,c2.y,100,100)    -- draw the 2nd circle    
end

function collide(c)
    if c.state==BEGAN then
        print("\
collision")
        print(c.id)
        print("radius of body A ",c.bodyA.radius)
        print("radius of body B ",c.bodyB.radius)
        print("position of body A ",c.bodyA.x)
        print("position of body A ",c.bodyA.y)
        -- see physics.contact and physics.body in the reference manual
        -- for other info that's available during a collision
    end   
end
7

ok. thanks! Ill check it out!

8

This just crashes. this is my code

     -- Use this function to perform your initial setup
    function setup()
        print("Hello World!")
        sx = WIDTH / 2
        sy = HEIGHT / 2
        x,y = 0,0
        tx, ty = 0,0
        c1 = physics.body(CIRCLE, 50)
        c1.type = STATIC
        c1.x = WIDTH / 2
        c1.y = 100
    end

    -- This function gets called once every frame
    function draw()
        background(127, 127, 127, 255)
        fill(0, 0, 0, 255)
        player()
        if move then
            sx=sx+(tx - x)/25
            sy=sy+(ty - y)/25
        end
        ellipse(c1.x, c1.y,50, 50)    
    
    end

    function touched(t)
        if t.x < WIDTH / 2 then
            if t.state == BEGAN then
                x = t.x
                y = t.y
                tx = x
                ty = y
                move = true
            elseif t.state == MOVING then
                tx = t.x
                ty = t.y
                move = true
            elseif t.state == ENDED then
                x,y = 0, 0
                tx, ty = 0,0
                move = false
            end
    end 
    end
    function player()
        playerc = physics.body(CIRCLE, 50)
        playerc.x = sx
        playerc.y = sy
        playerc.info = "player"
        sprite("Platformer Art:Guy Standing", playerc.x, playerc.y)
        sprite("Platformer Art:Guy Standing",playerc.x,playerc.y)
    end
    function collide(c)
        if c.state == BEGAN then
            print "collide"
        end
    end
9

@compactbear, please put 3 ~'s at the top and bottom of your code

10

thanks…

11

Move this code from player() into setup().

        playerc = physics.body(CIRCLE, 50)
        playerc.x = sx
        playerc.y = sy
        playerc.info = "player"
12

Thanks again Dave :wink:

13

How do I get rid of gravity and still be able to move from touching?

14

playerc.gravityScale=0

15

thansk

16

If I have the player() code in setup how do I switch it so I can move my player?

17

@compactbear I changed a few things that I think you’re trying to do.


displayMode(FULLSCREEN)   
    function setup()
        x,y = 0,0
        tx, ty = 0,0
        c1 = physics.body(CIRCLE, 50)
        c1.type = STATIC
        c1.x = WIDTH / 2
        c1.y = 100
        playerc = physics.body(CIRCLE, 50)
        playerc.x = WIDTH/2
        playerc.y = HEIGHT/2
        playerc.info = "player"
        playerc.sleepingAllowed=false
    end

    function draw()
        background(127, 127, 127, 255)
        fill(0, 0, 0, 255)
        player()
        if move then
            playerc.x=playerc.x+(tx - x)/25
            playerc.y=playerc.y+(ty - y)/25
            playerc.linearVelocity=vec2(0,0)
        end
        ellipse(c1.x, c1.y,100)    
    end

    function touched(t)
        if t.x<WIDTH/2 then
            if t.state == BEGAN then
                x = t.x
                y = t.y
                tx = x
                ty = y
                move = true
            elseif t.state == MOVING then
                if move==false then
                    x=t.x
                    y=t.y
                end
                tx = t.x
                ty = t.y
                move = true
            elseif t.state == ENDED then
                x,y = 0, 0
                tx, ty = 0,0
                move = false
            end
        else
            x,y = 0, 0
            tx, ty = 0,0
            move = false
        end           
    end
    
    function player()
        sprite("Platformer Art:Guy Standing", playerc.x, playerc.y)
    end
    
    function collide(c)
        if c.state == BEGAN then
            print "collide"
        end
    end
18

I got it now nvm

19

Thanks!

20

@compactbear I modified the above code so the sprite stops moving under the control of your finger once you cross the middle of the screen. This is in response to your other post. The sprite is still controlled by gravity and starts to fall.