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# Codea Wiki tutorial #3 fix

edited April 2013 Posts: 10

I'm trying to make a simple game in codea and looking at the tutorial (under getting started) I've recreated the ball example that has the circle bounce around the screen. However, when the user flicks the ball near the edge of the screen the ball gets stuck to the side of the screen. Is there a way to fix this?

Here is the code from the tutorial that I need in my program:

``````function setup()
x = WIDTH/2
y = HEIGHT/2
bc = color(248, 250, 13, 255)
tc = color(195, 17, 17, 255)
c = bc
inTouch = false
dx = 0
dy = 0
r = 30
end

function draw()
background(0, 0, 0, 255)
fill(c)
ellipse(x,y,r)
if inTouch then
x = tx
y = ty
c = tc
else
x = x +  dx
y = y +  dy
c = bc
end
if y > HEIGHT - r then
dy = - dy
end
if y < r then
dy = - dy
end
if x > WIDTH - r then
dx = - dx
end
if x < r then
dx = - dx
end
end

function touched(touch)
tx = touch.x
ty = touch.y
if touch.state == BEGAN then
inTouch = true
velocity = {}
end
if touch.state == MOVING then
table.insert(velocity,1,vec2(touch.deltaX,touch.deltaY))
end
if touch.state == ENDED then
dx = 0
dy = 0
n = 0
for i = 1,10 do
if velocity[i] then
n = n + 1
dx = dx + velocity[i].x
dy = dy + velocity[i].y
end
end
if n >0 then
dx = dx / n
dy = dy / n
end
inTouch = false
end
end
``````
Tagged:

• Posts: 1,542

• Posts: 2,161

(@Briarfox: I've edited that in now, @evanlws12 see how I've edited your post for how to include code so that it is readable.)

• Posts: 489

 ```... if y > HEIGHT - r then dy = - dy y = HEIGHT - r end if y < r then dy = - dy y = r end if x > WIDTH - r then dx = - dx x = WIDTH - r end if x < r then dx = - dx x = r end ...```
• edited April 2013 Posts: 5,396

I have a tutorial on that here

https://coolcodea.wordpress.com/2013/03/11/3-moving-an-object-around-the-screen/

Followed by more tutorials on how to use physics to do the same thing

• Posts: 10

Thanks everybody for the help, those tutorials will really help me in the future but whenever I implement these techniques to use the touch function, the ball gets stuck again! I still don't know how to make sure it doesn't get stuck on the sides

• Posts: 5,396

mpilgrem's code fixes the problem, I believe

• Posts: 10

It does! Sorry I think I had put it in the touch function by accident instead of the draw but I tried it again and it works, thank you.