BOUNCE.P

[Table of Contents]
BOUNCE.ATR Disk Image


BOUNCE.P shows how to use the GRAPHICS.I, PLOT.I, and DRAWTO.I include files to get a "ball" bouncing around the screen.

What's one the disk?

The disk image includes the various Atari DOS 2.5 files, Kyan Pascal Include files, Kyan Pascal Run-time library, and ...

GRAPHICS.I - Include file
PLOT.I - Include file
DRAWTO.I - Include file
BOUNCE.P - Source code file
P.OUT - Kyan Pascal intermediate file
BOUNCE - Executable file

Source Code

#A
_ORIGIN EQU $4000
#

Program BOUNCE(Input,Output);
Var
   x,y : Integer;
   dx, dy : Integer;
   minX, minY : Integer;
   maxX, maxY : Integer;
   oldX, oldY : Integer;
   i, j : Integer;   

#i Graphics.i
#i Plot.i
#i Drawto.i

Procedure Use_Graphics;
Begin
#A
   LDA #<_origin
   STA $6A
#
End;

Procedure Use_Text;
Begin
#A
   LDA #$C0
   STA $6A
#
End; (* of the Use_Text procedure *)

Begin
   (* Initialize graphics *)
   Use_Graphics;

   (* GR 3 with text 40x20 *)
   Graphics(3);

   minX := 0;
   minY := 0;
   maxX := 39;
   maxY := 19;
   dx := 1;
   dy := 1;

   (* Draw a border *)
   Plot(minX,minY,1);
   Drawto(maxX,minY,1);
   Drawto(maxX,maxY,1);
   Drawto(minX,maxY,1);
   Drawto(minX,minY,1);   

   (* Start location *)
   x := round(maxX / 2);
   y := round(maxY / 2);

   for i := 1 to 500 do
   begin
   
     plot(x,y,2);
     oldX := x;
     oldY := y;
  
     if (x<=minX+1) or (x>=maxX-1) then
        dx := -dx;

     if (y<=minY+1) or (y>=maxY-1) then
        dy := -dy;
     
     x := x + dx;
     y := y + dy;

     for j := 1 to 1500 do
     begin
        (* slow down *);
     end;

     plot(oldX,oldY,0);

   end;

   (* Back to text mode *)
   Use_Text;
   Graphics(0)
End.

Sample Run