Help- Pong game- Collision - GameCreators Forum

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They Killed Kenny

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Joined: 18th Jul 2004

Location: FL, USA

Posted: 3rd Feb 2005 08:32 Edited at: 6th Feb 2005 01:55

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I'm trying to make a pong game. This is my first game. I have made little madlib programs and stuff before this so I think I'm ready. The only problem is that I have no idea which type of collision detection to use for the ball and paddles.
Here's the code:

[You can Paste this code into your editor since it has no dependencies]

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 0
Player2Y = 0

ballx= 309
bally= 219

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

`ball collisions
   gosub ballhit_detection
   gosub collisions
   SYNC
LOOP

ballhit_detection:
   IF Start=1
      BallX=BallX+4
   ELSE
      IF BALLHIT2=1 THEN BALLX=BALLX-4 : BallY=RND(20)
      IF BallHIT1=1 THEN BALLX=BALLX+4 : Bally=RND(50)
   ENDIF
SPRITE 3,ballx,bally,2
return

Collisions:
IF SPRITE COLLISION(2,3)
   BALLHIT2=1
   BALLHIT1=0
ELSE
   BALLHIT2=0
   BALLHIT1=1
ENDIF

IF SPRITE COLLISION(1,3)
   BALLHIT1=1
   BALLHIT2=0
ELSE
   BALLHIT1=0
   BALLHIT2=1
ENDIF
return

+ Code Snippet

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 0
Player2Y = 0

ballx= 309
bally= 219

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

   IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

   IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

   `ball collisions
   gosub ballhit_detection
   gosub collisions
   SYNC
LOOP

ballhit_detection:
   IF Start=1
      BallX=BallX+4
   ELSE
      IF BALLHIT2=1 THEN BALLX=BALLX-4 : BallY=RND(20)
      IF BallHIT1=1 THEN BALLX=BALLX+4 : Bally=RND(50)
   ENDIF
SPRITE 3,ballx,bally,2
return


Collisions:
IF SPRITE COLLISION(2,3)
   BALLHIT2=1
   BALLHIT1=0
ELSE
   BALLHIT2=0
   BALLHIT1=1
ENDIF

IF SPRITE COLLISION(1,3)
   BALLHIT1=1
   BALLHIT2=0
ELSE
   BALLHIT1=0
   BALLHIT2=1
ENDIF
return

Maybe I should make the collision simple, like this:

+ Code Snippet

collision:
IF SPRITE COLLISION (3,2)
BALLX=BALLX*1
BALLY=(BALLY+ RND (20))*-1

Stan: OH MY GOD! THEY KILLED KENNY
Stan's Grandpa: You Bastards!
Kyle: HEY! ><

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Ric

20

Years of Service

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Joined: 11th Jul 2004

Location: object position x

Posted: 4th Feb 2005 09:05 Edited at: 4th Feb 2005 09:06

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For 2-d, I'd do collision by detecting if the ball has gone past certain coordinates - something like this:

+ Code Snippet

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 0
Player2Y = 0

ballx= 309
bally= 219

xspeed=4

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

   IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

   IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

   `ball collisions
   gosub ball_movement
   gosub collisions
   SYNC
LOOP

ball_movement:

      ballx=ballx+xspeed
      bally=bally+yspeed

SPRITE 3,ballx,bally,2
return


Collisions:

if ballx<30 and bally<Player1Y+110 and bally>Player1Y then xspeed=xspeed*-1

if ballx>580 and bally<Player2Y+110 and bally>Player2Y then xspeed=xspeed*-1



return

You'd need to fiddle a bit to get the numbers exactly right, though.

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They Killed Kenny

20

Years of Service

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Joined: 18th Jul 2004

Location: FL, USA

Posted: 6th Feb 2005 01:50 Edited at: 6th Feb 2005 01:58

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Hm... but then what in the world is the Sprite Collision Command for? And how do you use it? When I use it, it doesnt detect anything and the ball just goes through it.

I'll try it to see if it works

Stan: OH MY GOD! THEY KILLED KENNY
Stan's Grandpa: You Bastards!
Kyle: HEY! ><

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Ric

20

Years of Service

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Joined: 11th Jul 2004

Location: object position x

Posted: 6th Feb 2005 07:40 Edited at: 6th Feb 2005 07:45

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Using sprite collision, it would be like this .....

+ Code Snippet

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 0
Player2Y = 0

ballx= 309
bally= 219

xspeed=4

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

   IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

   IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

   `ball collisions
   gosub ball_movement
   gosub collisions
   SYNC
LOOP

ball_movement:

      ballx=ballx+xspeed
      bally=bally+yspeed

SPRITE 3,ballx,bally,2
return


Collisions:

if sprite collision(3,1)=1 then xspeed=xspeed*-1

if sprite collision(3,2)=1 then xspeed=xspeed*-1



return

..... although sprites have a tendency to pass through each other if they're moving too fast if you use the sprite collision command.

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They Killed Kenny

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Years of Service

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Joined: 18th Jul 2004

Location: FL, USA

Posted: 6th Feb 2005 08:54

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Buggy commands ><.
Ok I'l try it
-studies the code-

Stan: OH MY GOD! THEY KILLED KENNY
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Kyle: HEY! ><

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They Killed Kenny

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Years of Service

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Joined: 18th Jul 2004

Location: FL, USA

Posted: 6th Feb 2005 23:36 Edited at: 6th Feb 2005 23:44

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Yay it worked! The ball isn't moving too fast for the paddles to hit it!

But now I want it to Bounce off the bottom and Top. Normally, it bounces off the bottom (usually) but not at the top (usually).... the logic is perfectly fine... I dont get whats wrong... Here is the Subroutine:

+ Code Snippet

bottom_top_collisions:
IF BALLY=459 THEN YSPEED=YSPEED*-1
IF BALLY=0 THEN YSPEED=YSPEED*-1

return

And here is the whole code.... I have a feeling it is conflicting with something... but I dont know why. Maybe i should put a Sync Command in the Subroutine?

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 210
Player2Y = 210

ballx= 309
bally= 219

xspeed=4
yspeed=0

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

`ball collisions
   gosub ball_movement
   gosub collisions
   gosub bottom_top_collisions
   SYNC
LOOP

ball_movement:

ballx=ballx+xspeed
      bally=bally+yspeed

SPRITE 3,ballx,bally,2
return

Collisions:

if sprite collision(3,1)=1
   xspeed=xspeed*-1
   yspeed=yspeed+RND(5)
ENDIF

if sprite collision(3,2)=1
   xspeed=xspeed*-1
   yspeed=yspeed+RND(5)
ENDIF
return

bottom_top_collisions:
IF BALLY=459 THEN YSPEED=YSPEED*-1
IF BALLY=0 THEN YSPEED=YSPEED*-1

return

+ Code Snippet

`Start up
Sync On
Sync Rate 60

`declare variables
Player1Y = 210
Player2Y = 210

ballx= 309
bally= 219

xspeed=4
yspeed=0

Start=1
ballhit=0

`get image from box and circle
BOX 0,0,30,110
GET IMAGE 1,0,0,30,110
CLS

CIRCLE 10,10,10
GET IMAGE 2,0,0,21,21
CLS
`Core Program
DO
   `determine whether or not the ball has hit a paddle

   IF UPKEY()=1 THEN Player1Y= Player1Y - 4
   IF DOWNKEY()=1 THEN PLAYER1Y = PLAYER1Y + 4
   SPRITE 1,0,PLAYER1Y,1

   IF KEYSTATE(72)=1 THEN Player2Y= Player2Y - 4
   IF KEYSTATE(80)=1 THEN PLAYER2Y = PLAYER2Y + 4
   SPRITE 2,610,PLAYER2Y,1

   `ball collisions
   gosub ball_movement
   gosub collisions
   gosub bottom_top_collisions
   SYNC
LOOP

ball_movement:

      ballx=ballx+xspeed
      bally=bally+yspeed

SPRITE 3,ballx,bally,2
return


Collisions:

if sprite collision(3,1)=1
   xspeed=xspeed*-1
   yspeed=yspeed+RND(5)
ENDIF

if sprite collision(3,2)=1
   xspeed=xspeed*-1
   yspeed=yspeed+RND(5)
ENDIF
return

bottom_top_collisions:
IF BALLY=459 THEN YSPEED=YSPEED*-1
IF BALLY=0 THEN YSPEED=YSPEED*-1

return

Stan: OH MY GOD! THEY KILLED KENNY
Stan's Grandpa: You Bastards!
Kyle: HEY! ><

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Ric

20

Years of Service

User Offline

Joined: 11th Jul 2004

Location: object position x

Posted: 7th Feb 2005 00:45

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Change to:

+ Code Snippet

IF BALLY>459 THEN YSPEED=YSPEED*-1
IF BALLY<0 THEN YSPEED=YSPEED*-1

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