Many Balls bouncing

Cervantes · **Posted:** Mon Feb 16, 2004 7:56 pm

It's kinda like thinking in another dimension.. I guess Confused

Everyone how has spoken in this thread so far could do that with one ball. Two balls? Yes, just have 2 x vars and 2 y vars etc. 100 balls? It's harder, but it really isn't that hard.

When you've got the for loops going 100 balls is basically simplified into 1 ball. Wherever you would say something like

code:

ballx += balldx
bally += balldy

you actually have

code:

for i : 1 .. howmanyballs
ballx (i) += balldx (i)
bally (i) += balldy (i)
end for

xmen · **Posted:** Fri Mar 26, 2004 7:16 pm

Cervantes wrote:

....

code:

View.Set ("position:centre;centre,graphics:300;300,title:Bouncing Balls,nobuttonbar")
var totalballs : int := 15 %NOTE : to increase how many balls will spawn this number must be at least equal to the max number of balls
var x, y, dx, dy : array 1 .. totalballs of int
var dx_temp, dy_temp : array 1 .. totalballs of real
var movedist1, movedist2, collangle, mass, a1, a2, nX, nY, optimisedP : real

var px, py : int
px := maxx div 2
py := maxy div 2
var keys : array char of boolean
var hit : boolean := false
var respawn : boolean := true
var respawnx, respawny : int
var lives : int := 3
const ballradius := 8
const ballcollidedistance := ballradius * 2
var timer : int
setscreen ("offscreenonly")
mass := 1

for i : 1 .. totalballs
x (i) := Rand.Int (20 + ballradius, maxx - 20 - ballradius)
y (i) := Rand.Int (20 + ballradius, maxy - 20 - ballradius)
dx (i) := Rand.Int (-3, 3)
dy (i) := Rand.Int (-3, 3)
end for

proc drawscreen
for i : 1 .. maxx by 20
Draw.FillStar (i, 0, i + 20, 20, 2)
Draw.FillStar (i, maxy - 20, i + 20, maxy, 2)
end for
for k : 20 .. maxy - 20 by 20
Draw.FillStar (0, k, 20, k + 20, 2)
Draw.FillStar (maxx - 20, k, maxx, k + 20, 2)
end for
locate (3, 3)
end drawscreen

proc ball_movement
for i : 1 .. totalballs
%wall bouncing
if x (i) > maxx - 20 - ballradius then
dx (i) := -dx (i)
x (i) += dx (i)
end if
if x (i) < 20 + ballradius then
dx (i) := -dx (i)
x (i) += dx (i)
end if
if y (i) > maxy - 20 - ballradius then
dy (i) := -dy (i)
y (i) += dy (i)
end if
if y (i) < 20 + ballradius then
dy (i) := -dy (i)
y (i) += dy (i)
end if

x (i) += dx (i)
y (i) += dy (i)
drawfilloval (x (i), y (i), ballradius, ballradius, blue)
end for
end ball_movement

proc balls_collide
for i : 1 .. totalballs
for k : i .. totalballs

if k not= i then
if Math.Distance (x (i), y (i), x (k), y (k)) < ballcollidedistance then
%CREDIT : THOUGHTFUL
if y (k) - y (i) not= 0 and x (k) - x (i) not= 0 then
collangle := arctand ((y (k) - y (i)) / ((x (k) - x (i))))

nX := cosd (collangle)
nY := sind (collangle)

a1 := x (i) * nX + y (i) * nY
a2 := x (k) * nX + y (k) * nY

optimisedP := (2.0 * (a1 - a2)) / (mass + mass)

x (i) := x (i) - (round (optimisedP) * round (mass) * round (nX))
y (i) := y (i) - (round (optimisedP) * round (mass) * round (nY))
x (k) := x (k) + (round (optimisedP) * round (mass) * round (nX))
y (k) := y (k) + (round (optimisedP) * round (mass) * round (nY))
% moves the balls forward a step so they dont get stuck with each other( but the balls will still stick)
x (i) += dx (i)
y (i) += dy (i)
x (k) += dx (k)
y (k) += dy (k)
end if
end if
end if
end for
end for
end balls_collide

proc player_control
Input.KeyDown (keys)
if keys (KEY_UP_ARROW) then
py += 2
end if
if keys (KEY_DOWN_ARROW) then
py -= 2
end if
if keys (KEY_RIGHT_ARROW) then
px += 2
end if
if keys (KEY_LEFT_ARROW) then
px -= 2
end if
drawfilloval (px, py, ballradius, ballradius, brightred)
end player_control

proc player_boundaries
if px > maxx - 50 - ballradius then
px := maxx - 50 - ballradius
end if
if px < 50 + ballradius then
px := 50 + ballradius
end if
if py > maxy - 50 - ballradius then
py := maxy - 50 - ballradius
end if
if py < 50 + ballradius then
py := 50 + ballradius
end if
end player_boundaries

proc relocate
lives -= 1
delay (1000)
px := 20 + ballradius
py := 20 + ballradius
end relocate

loop
timer := Time.Elapsed
totalballs := round (timer / 5000)
exit when totalballs > 20 or hit = true
cls
drawscreen

player_control
player_boundaries

ball_movement
balls_collide
for k : 1 .. totalballs
if Math.Distance (px, py, x (k), y (k)) < ballcollidedistance then
hit := true
end if
end for
View.Update
delay (10)
end loop

delay (500)
cls
locate (7, 5)

put "Thanks for playing,\n -Cervantes"

its not nearly done but w/e just for fun Smile

at first when i was running this program it went fine. but after awhile, an error suddenly pops up saying "array subscript is out of range" for:

Cervantes wrote:

....
if x (i) > maxx - ballradius then

do any of u kno why??
i also notice when i change the # of balls n the radius of balls this error appears earlier.....plzz show me how to fix this

xmen · **Posted:** Fri Mar 26, 2004 7:57 pm

how come sometimes the balls move very slowly while sometimes very fast??

how can i fix the problem where the ball get stuck on one of the sides (kinda start shaking)

Hackster · **Posted:** Sat Mar 27, 2004 12:44 am

Here's a bouncy ball program that is in a totally random pattern

code:

% The "Jumble" program.
setscreen ("offscreenonly")
colorback (42)
cls

% Place some circles around the screen
const radius : int := 30
const ball : int := 20
var x, y, dx, dy, clr : array 1 .. ball of int
for i : 1 .. ball
x (i) := Rand.Int (radius, maxx - radius)
y (i) := Rand.Int (radius, maxy - radius)
dx (i) := Rand.Int (-3, 3)
dy (i) := Rand.Int (-3, 3)
clr (i) := Rand.Int (16, 32)
end for

loop
cls % Clear the offscreen window
for i : 1 .. ball
if x (i) + dx (i) < radius or
x (i) + dx (i) > maxx - radius then
dx (i) := -dx (i)
end if
if y (i) + dy (i) < radius or
y (i) + dy (i) > maxy - radius then
dy (i) := -dy (i)
end if
x (i) := x (i) + dx (i)
y (i) := y (i) + dy (i)
Draw.FillOval (x (i), y (i), radius, radius, clr (i))
end for
View.Update
delay (1)
end loop

hope you like!

Cervantes · **Posted:** Sat Mar 27, 2004 10:13 am

[quote=xmen][quote=Cervantes]....
if x (i) > maxx - ballradius then[/quote]
do any of u kno why??[/quote]

That would be because that line of code is not actually part of my program Laughing

no idea how you got that, but its:

code:

if x (i) > maxx - 20 - ballradius then

that code simply tells if the x position of ball (i) has hit the wall or not.

xmen, how did you last long enough to notice that things speed up or slow down!! you must have made some alterations on my code, because I can't get past 7 of those guys Razz

I guess it does depend on the speed of your computer though. I'm on 1.6ghz 512 mb of ram. What do you have? If your on a relatively slow computer it probably explains why the speed of the balls change: because as more balls are added the program has to go through the for loops more times, taking up more time.

xmen · **Posted:** Sat Mar 27, 2004 7:03 pm

my computer is 1.8 P4 / 256 ram.....well all i did was decrease the # of max balls (in the beginning of program) to like 4, n take out the red ball, everytime i run the program its different

sometimes the first blue ball goes very slow, then the second ball goes very fast, n if any of the balls hit the slow one, the slow one turns fast while the fast one turn slow.....etc

also if i make the size of the ball bigger, once they collide there are some bugs there too, n sometimes these balls just slide along the sides for some reason

i kno these are pretty simple n stupid questions but i reli need answers for them......cuz later on im gonna change the balls into happy faces n make this as screensaver (as one of my assignment).........thnx

Cervantes · **Posted:** Sat Mar 27, 2004 7:42 pm

You can use my code as a reference, but don't cut and paste and change a few things to make it look like your own code. Just a warning, I don't know if you were planning on doing that or not.
Anyways, take a look at this part of the program:

code:

for i : 1 .. totalballs
x (i) := Rand.Int (20 + ballradius, maxx - 20 - ballradius)
y (i) := Rand.Int (20 + ballradius, maxy - 20 - ballradius)
dx (i) := Rand.Int (-3, 3)
dy (i) := Rand.Int (-3, 3)
end for

This explains why certain balls begin at a faster pace then others. dx represents the balls speed along the x axis, and dy represents the balls speed along the y axis.
later, this code appears:

code:

x (i) += dx (i)
y (i) += dy (i)

that code is inside the main loop, so every time that code executes, the value of dx is added to x, and dy to y.
Because dx and dy are created using Rand.Int, the balls begin with different speeds.
As for when they collide, the balls transfer energy between each other, speeding one up and slowing the other down.
you should note though that the collision data in this is rather messed up though.

xmen · **Posted:** Sat Mar 27, 2004 11:10 pm

Cervantes hav u tried letting ur program run for awhile (with like 6 balls, delete the red one) n get this error saying "array subscript is out of range" ??

how do i fix that??

Cervantes · **Posted:** Sun Mar 28, 2004 10:30 am

you fix that by increasing the totalballs variable at the top of the program.

xmen · **Posted:** Sun Mar 28, 2004 11:58 am

but wut if i only want 6 balls appearin in total??
well wut ive tried was set the totalballs to a large nuber (like 50, so that the program can continue longer) n then i put exit when i=7 to the part of actually drawin the balls

this worked completely fine (only 6 balls appeared) BUT if i was to leave the program on longer, it'll laaaaaaaaaaaaaaaggggggg like crazy, not cuz of my system, it was bcuz of the colliding part of this program was still calculating stuffs using the totalballs ive set (50)

so is there any way i can hav this program run forever with only like 6 balls but no lag afterwards??

Cervantes · **Posted:** Sun Mar 28, 2004 12:32 pm

uh-huh. all you do is set totalballs to 6 and comment out the bit about the timer.

xmen · **Posted:** Sun Mar 28, 2004 2:01 pm

ok thnx

sry but one last question.......u see rite now im making screensaverS for an assignment. it starts with a "menu" (just simply with GUI buttons) for viewing the 5 screensavers, so the first button is screen 1 n etc

but the problem is, if i was to copynpaste all 5 screensavers' codes and complie them into one program for this assignment, im thinking that i'll lag quite alot (especially with school computers). so i justwanna ask u if theres a command (for GUI button procedure) to read n run another turing file/program once i click GUI button 1,2,3...... so i'll hav 6 programs
with 5 screensavers and one "menu" page

Cervantes · **Posted:** Sun Mar 28, 2004 6:57 pm

F10 on include

Homer_simpson · **Posted:** Mon Mar 29, 2004 2:57 am

we64 wrote:

I changed it based on Cervantes' code... Now it really bouncing around screen...

code:

var howmany : int
put "How many balls? : " ..
get howmany
var x, y, dx, dy : array 1 .. howmany of int
for i : 1 .. howmany
dx (i) := Rand.Int (-4, 4)
dy (i) := Rand.Int (-4, 4)
x (i) := maxx div 2
y (i) := maxy div 2
end for
setscreen ("offscreenonly")
cls
loop
cls
for k : 1 .. howmany
x (k) += dx (k)
y (k) += dy (k)
Draw.FillOval (x (k), y (k), 5, 5, brightred)
if x (k) >= maxx or x (k) <= 0 then
dx (k) := -dx (k)
elsif y (k) >= maxy or y (k) <= 0 then
dy (k) := -dy (k)
end if
end for
View.Update
delay (5)
end loop

here's a little something to make that look better:

code:

var howmany : int
put "How many balls? : " ..
get howmany
var x, y, dx, dy,a : array 1 .. howmany of real
for i : 1 .. howmany
dx (i) := Rand.Int (-4, 4)
dy (i) := Rand.Int (-4, 4)
a (i) := Rand.Int (0, 100)/100
x (i) := maxx div 2
y (i) := maxy div 2
end for
setscreen ("offscreenonly")
cls
loop
cls
for k : 1 .. howmany
x (k) += dx (k)*a(k)
y (k) += dy (k)*a(k)
Draw.FillOval (round(x (k)), round(y (k)), 5, 5, brightred)
if x (k) >= maxx or x (k) <= 0 then
dx (k) := -dx (k)
elsif y (k) >= maxy or y (k) <= 0 then
dy (k) := -dy (k)
end if
end for
View.Update
delay (5)
end loop

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