Computer Science Canada

setscreen ("graphics")
var c, dx, dy, r, cx, cy, b, a, d, e, f, g : int := 0
var q : string (1)
var strc : string
var colours : array 0 .. 15 of string := init ("black", "dark blue", "dark green", "dark cyan", "dark red", "dark magneta", "brown", "white", "grey", "blue", "green", "cyan", "red", "magenta",
"yellow", "bright white")

loop

put " Enter Radius of ball 1 and 2 "
get r, a
put " Enter a Colour of ball 1 "
get strc : *
for i : 0 .. 15
if strc = colours (i) then
c := i
end if
end for
put " Enter a Colour of ball 2 "
get strc : *
for i : 0 .. 15
if strc = colours (i) then
c := i
end if
end for
cx := Rand.Int (r, maxx - r)
cy := Rand.Int (r, maxy - r)
dx := 1
dy := 1
d := Rand.Int (a, maxx - a)
e := Rand.Int (a, maxy - a)

f := -1
g := -1
loop

exit when hasch

drawfilloval (cx, cy, r, r, c)
delay (10)
drawfilloval (cx, cy, r, r, white)
drawfilloval (d, e, a, a, b)
delay (10)
drawfilloval (d, e, r, r, white)

d += f
e += g

cx += dx
cy += dy

if d >= maxx - a or d <= a then
f := -f
g := -g
end if
if cx >= maxx - r or cx <= r then
dx := -dx
dy := -dy
end if

if e > maxy - a or e <= a then
g := -g
f := -f

end if

if cy > maxy - r or cy <= r then
dy := -dy
dx := -dx

end if

end loop

end loop

var x, y := 200
var dirx, diry := true
View.Set ("offscreenonly")
loop
drawfilloval (x, y, 10, 10, 9)
View.Update
delay (1)
cls
case dirx of
label true :
x += 2
label false :
x -= 2
end case
case diry of
label true :
y -= 1
label false :
y += 1
end case
if x >= 630 or x <= 0 then
dirx := not dirx
end if
if y >= 390 or y <= 0 then
diry := not diry
end if

end loop

function distance (x1, y1, x2, y2 : int) : int
result round (((x1 - x2) ** 2 + (y1 - y2) ** 2) ** .5)
end distance

var x1, y1 := 100
var x2, y2 := 10
var dirx1, diry1 := false
var dirx2, diry2 := true
View.Set ("offscreenonly")
loop
drawfilloval (x1, y1, 50, 50, 9)
drawfilloval (x2, y2, 50, 50, 4)
View.Update
delay (1)
cls

case dirx1 of
label true :
x1 += 2
label false :
x1 -= 2
end case
case diry1 of
label true :
y1 -= 1
label false :
y1 += 1
end case
if x1 >= 630 or x1 <= 0 then
dirx1 := not dirx1
end if
if y1 >= 390 or y1 <= 0 then
diry1 := not diry1
end if

case dirx2 of
label true :
x2 += 1
label false :
x2 -= 1
end case
case diry2 of
label true :
y2 -= 2
label false :
y2 += 2
end case
if x2 >= 630 or x2 <= 0 then
dirx2 := not dirx2
end if
if y2 >= 390 or y2 <= 0 then
diry2 := not diry2
end if

%collide
if distance (x1, y1, x2, y2) < 100 then
dirx2 := not dirx2
diry2 := not diry2
dirx1 := not dirx1
diry1 := not diry1
end if
end loop

Author:	Tony [ Tue Apr 15, 2003 1:44 pm ]
Post subject:
well the basic idea is to change the direction of movement after the collision. You should read a tutorial on circular collisions. To realistically bounce balls from each other, read a tutorial on "making a pool game". It describes the physics behind ball colision and gives some code examples of how to code it. You should use it as a guide only though since it was programmed as an animation so it would bug if you just copy/paste it into your program. You can find all the reading material in the "tutorials" section of this site.

Author:	SilverSprite [ Sat Apr 26, 2003 11:07 am ]
Post subject:
What does this line do? dirx := not dirx

Author:	Martin [ Sat Apr 26, 2003 11:08 am ]
Post subject:
Toggle's dirX not true = false not false = true therefor, not dirX = true if dirX = false, and vise versa

Author:	void [ Thu May 01, 2003 5:33 pm ]
Post subject:	paddle game
okay....i have this thing for paddle ball game where i tell the porgram that if the lowest point in the ball touches any part of the top of the paddle....then bounce it back....and i have everything perfectly fine.....(i used the same program structure that i saw on here before for the bouncing balls...but i edited it so that if its below 0 on the y-axis...then exit the loop thats drawing the ball....but now im stuck....i need an idea that will allow me to repeat the process for 3 times (the user has three balls to use).....any ideas .....im up for anything

Author:	Tony [ Thu May 01, 2003 5:51 pm ]
Post subject:
well put that loop inside another loop. Every time you exit your inside loop you add one to used up lifes counter. When the counter reaches 3, that means you used up your 3rd ball and its game over. Otherwise your outside loop returns you to the beginning of your inside loop

Author:	Homer_simpson [ Thu May 01, 2003 6:27 pm ]
Post subject:
or u can make a variable and everytime ball misses add the value of the variable by 1 and exit loop when variable = 3