bouncing ball??

[hpdudette]

i'm trying to make this ball bounce in diagonally across the screen but i can't seem to figure out how to make it bounce back or bounce from top to bottom

code:

for x:10..360     drawfilloval (x, x, 30, 30, 4)     delay (5)     drawfilloval (x, x, 30, 30, 0) end for

[PaddyLong]

easiest way to do a bouncing ball around the screen is something like this...

code:

const speed := 5 %the ammount the ball is moved const radius := 25 %the radius of the ball var xmove, ymove : int := speed %the amount it moves on the x and y axis var x, y : int %the ball's x and y coordinates on the screen var colr : int := 7 %the colour of the ball %start the ball in the middle of the screen x := maxx div 2 y := maxy div 2 loop     %draw the ball, wait a short time, then draw a white one on top of it     drawfilloval (x, y, radius, radius, colr)     delay (25)     drawfilloval (x, y, radius, radius, 0)     %move the ball's coordinates the respective x and y amounts     x += xmove     y += ymove     if x >= maxx - radius or x <= radius then         %if the middle of the ball (x) is at the edge of the screen         xmove *= -1 %switch the x direction     end if     if y >= maxy - radius or y <= radius then         %if the middle of the ball (y) is at the top of bottom of the screen         ymove *= -1  %switch the y direction     end if end loop

[naoki]

i use something like

if ballx is near 0 or maxx then
xchange := - xchange
end if
if bally is near 0 or maxy then
ychange := ychange
end if
ballx += xchange
bally += ychange

this way only the increment by which you're moving the ball left/right, up/down will change from negative to positive, thus doing all the work for you

[PaddyLong]

that's what mine is doing by multiplying it by -1 ..