Strange glitch problem in my game

Author

Message

Sli3her

15

Years of Service

User Offline

Joined: 20th Feb 2011

Location: Deep in code...

Posted: 29th Feb 2012 16:17

Link

I'm currently working on a Pong clone game that I have many great ideas for. At the moment though I'm having problems with the AI paddle not stopping at the top of the screen. I've used this same code to stop sprites from moving off the screen before so I'm kinda baffled at what's going on. Below is the function that is supposed to be stopping the paddle. The paddle will stop at the bottom of the screen, but, for some odd reason when it hits the top of the screen it reappears at the bottom. I've also included the link to my game so you can see better what's happening.

+ Code Snippet

FUNCTION MoveAIPaddle()
    
    CenterOfPaddle = PaddleTwoY + (SPRITE HEIGHT(PaddleTwoSprite) / 2)    ` CENTER OF THE PADDLE Y-AXIS
    BottomOfScreen = SCREEN HEIGHT() - SPRITE HEIGHT(PaddleTwoSprite)   ` AS FAR AS THE PADDLE CAN GO DOWN

    IF CenterOfPaddle < BallY THEN INC PaddleTwoY, PaddleTwoSpeed           ` PADDLE IS HIGHER THAN BALL - MOVE DOWN
    IF PaddleTwoY > BottomOfScreen THEN PaddleTwoY = BottomOfScreen     ` BOTTOM OF SCREEN
    
    IF CenterOfPaddle > BallY THEN DEC PaddleTwoY, PaddleTwoSpeed           ` PADDLE IS LOWER THAN BALL - MOVE UP
    IF PaddleTwoY < 0 THEN PaddleTwoY = 0                                             ` PADDLE IS AT TOP OF SCREEN
    
    SPRITE PaddleTwoSprite, PaddleTwoX, PaddleTwoY, PaddleTwoImage        ` DRAW PADDLE TO SCREEN

ENDFUNCTION

Link to game: http://mrhtml16.angelfire.com

Back to top

Profile PM

Penfold

22

Years of Service

User Offline

Joined: 3rd Dec 2003

Location: RED postbox houses of parliment

Posted: 29th Feb 2012 19:44 Edited at: 29th Feb 2012 19:45

Link

/try moddifying your code so it only checks if its too far up or down if it actually travels that way. at the moment it seems to triggering the line of code that makes the height the bbotom of the screen as if when the y goes into a negative it becomes greater than the bottom of the screen

try the following code

IF CenterOfPaddle < BallY
INC PaddleTwoY, PaddleTwoSpeed `PADDLE IS HIGHER THAN BALL- MOVE DOWN
IF PaddleTwoY > BottomOfScreen THEN PaddleTwoY = BottomOfScreen `BOTTOM OF SCREEN
Endif

..and alter the up code to similar style

'Ooh 'eck chief'...'crumbs'

Back to top

Profile PM

Sli3her

15

Years of Service

User Offline

Joined: 20th Feb 2011

Location: Deep in code...

Posted: 1st Mar 2012 04:13

Link

Thanks for your help. The problem wasn't with the code itself but rather the variable type I was using. I was using a WORD variable instead of an INTEGER. The paddle Y value must have been going past the top of the screen and since WORD variables don't support negative numbers it seems as though it was wrapping to the bottom of the screen, and then the code that is responsible for checking to see if the paddle is at the bottom was executing causing the paddle to "glitch" all the way down.

Back to top

Profile PM

Penfold

22

Years of Service

User Offline

Joined: 3rd Dec 2003

Location: RED postbox houses of parliment

Posted: 1st Mar 2012 12:31

Link

glad its fixed

'Ooh 'eck chief'...'crumbs'

Back to top

Profile PM

Sorry your browser is not supported!

DarkBASIC Professional Discussion / Strange glitch problem in my game