Add Boundaries

[SunsFan13]

Hey again.
How would I go about adding boundaries to the following program?
As it is right now, the 'balls' just go right off the screen until you bring them back..
I know, or think, its something to do with maxx and maxy.
Help me out here?

Thanks,
-Chris

code:

Text.Color (brightblue) put "Use the arrow keys to move the red ball." put "Use W,A,S,D to move the green ball." colorback (black) delay (2200) cls  % Clear Screen process ball1     setscreen ("graphics")     var key : array char of boolean     var x, y, r : int     x := maxx div 2 % Start at center     y := maxy div 2 % Start at center     r := 10 % Ball radius     loop         % Draw circle         drawfilloval (x, y, r, r, brightred)         Input.KeyDown (key)         % Move Left         if key (KEY_LEFT_ARROW) then             delay (85)             drawfilloval (x, y, r, r, black)             x := x - r             % Move Right         elsif key (KEY_RIGHT_ARROW) then             delay (85)             drawfilloval (x, y, r, r, black)             x := x + r             % Move Up         elsif key (KEY_UP_ARROW) then             delay (85)             drawfilloval (x, y, r, r, black)             y := y + r             % Move Down         elsif key (KEY_DOWN_ARROW) then             delay (85)             drawfilloval (x, y, r, r, black)             y := y - r         end if     end loop end ball1 %End process ball1 colorback (black) process ball2 %Begin process ball2     var key : array char of boolean     var x, y, r : int     x := maxx div 3     y := maxy div 3     r := 10 % Ball radius     loop         % Draw circle         drawfilloval (x, y, r, r, brightgreen)         Input.KeyDown (key)         % Move Left         if key ('a') then             delay (85)             drawfilloval (x, y, r, r, black)             x := x - r             % Move Right         elsif key ('d') then             delay (85)             drawfilloval (x, y, r, r, black)             x := x + r             % Move Up         elsif key ('w') then             delay (85)             drawfilloval (x, y, r, r, black)             y := y + r             % Move Down         elsif key ('s') then             delay (85)             drawfilloval (x, y, r, r, black)             y := y - r         end if     end loop end ball2 fork ball1 fork ball2

[BigBear]

First I would suggest not using process except for music and only for that in older versions because multiple process randomly run one or the other so the outcome of the program can be different every time. Instead you should have one loop that gets the input for both players and moves both the balls with 2 if statements.
Here is a full explanation http://compsci.ca/v3/viewtopic.php?t=7842

Now the boundaries part, when you move the circles around you know where there are. For example ball1 starts in the middle and if you go left then it is one pixel left of the center. To make sure they do not leave the screen you need to only move

Left - if they are not right next to the left side of the screen
Right - if they are not right next to the right edge of the screen
Up - if they are not at the top of the screen
Down - if they are not at the bottom of your screen

So now you have to put the above into if statements when you check to see what key they entered.
Note: left side of screen is 0, right side of screen is maxx (or maxx minus something), top of screen is maxxy and bottom is 0.

You still need to figure out when which part is at 0 or a maxx/maxy of the screen.

Hope this helps.

[SunsFan13]

Yeah, got it.
Thanks Bear.

.. Last part I gotta figure out is how to get it to display something (ie. "You Win") when one ball hits the second ball.

[BigBear]

Well that seem like a weird win condition especially if it is a two player game. You meant when one user controlled circle get a randomly placed non-movable circle right? A race to the circle sounds interesting.

Same type of thing collision detection check to see if the coordinates of the user controlled circle is inside the coordinates of the non-movable circle. I am sure you can figure it out because you solved the first problem with very little help. There a many tutorials on collision detection you should check out.

[Sean]

If you are building the game as a race to the other dot between both players, you will want to check the x and y position of both dots, and see which one matches the destination dot.

You will need to do a comparison between the x and y co-ordinates of the player to the dot in one if statement. In your if statement, you will need a put statement with the desired message.

You may run into trouble where both equal it, and will have both messages appearing.

[Tallguy]

use a for statement for ur maxx maxy etc, and if the ball enters the set distances the balls bounce back, this is one of the simplest ways

[andrew.]

Do it like this:

Turing:

Text.Color (brightblue) put "Use the arrow keys to move the red ball." put "Use W,A,S,D to move the green ball." colorback (black) Input.Pause cls  % Clear Screen setscreen ("graphics:offscreenonly") var key : array char of boolean var x, y, r, a, b, c : int x := maxx div 2     % Start at center y := maxy div 2     % Start at center r := 10     % Ball radius a := maxx div 3 b := maxy div 3 c := 10     % Ball radius loop     % Draw circle     drawfilloval (x, y, r, r, brightred)     Input.KeyDown (key)     % Move Left     if key (KEY_LEFT_ARROW) then         drawfilloval (x, y, r, r, black)         x := x - r         % Move Right     elsif key (KEY_RIGHT_ARROW) then         drawfilloval (x, y, r, r, black)         x := x + r         % Move Up     elsif key (KEY_UP_ARROW) then         drawfilloval (x, y, r, r, black)         y := y + r         % Move Down     elsif key (KEY_DOWN_ARROW) then         drawfilloval (x, y, r, r, black)         y := y - r     end if     colorback (black)     % Draw circle     drawfilloval (a, b, c, c, brightgreen)     Input.KeyDown (key)     % Move Left     if key ('a') then         drawfilloval (a, b, c, c, black)         a := a - c         % Move Right     elsif key ('d') then         drawfilloval (a, b, c, c, black)         a := a + c         % Move Up     elsif key ('w') then         drawfilloval (a, b, c, c, black)         b := b + c         % Move Down     elsif key ('s') then         drawfilloval (a, b, c, c, black)         b := b - c     end if     % This is where the magic happens (lol)     if x > maxx - 10 then         x := maxx - 10     elsif x < 10 then         x := 10     end if     if a > maxx - 10 then         a := maxx - 10     elsif a < 10 then         a := 10     end if     if y > maxy - 10 then         y := maxy - 10     elsif y < 10 then         y := 10     end if     if b > maxy - 10 then         b := maxy - 10     elsif b < 10 then         b := 10     end if     View.Update     delay (15) end loop

I also got rid of your forks. You shouldn't use those unless you want background music.