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 ball bouncing help
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Stormtrooper




PostPosted: Tue Apr 15, 2003 12:58 pm   Post subject: ball bouncing help

ok i made this code and i want the balls to bounce when they hit eachother what should i add to the programm and where to put it? also my 2 balls are in each other how do i make them to be by them selves and move into different directions?


code:
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



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Tony




PostPosted: Tue Apr 15, 2003 1:44 pm   Post subject: (No 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.
Latest from compsci.ca/blog: Tony's programming blog. DWITE - a programming contest.
Homer_simpson




PostPosted: Fri Apr 25, 2003 10:41 pm   Post subject: (No subject)

i believe this is what you have been trying to make ?...
code:
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
SilverSprite




PostPosted: Sat Apr 26, 2003 11:07 am   Post subject: (No subject)

What does this line do?

dirx := not dirx
Martin




PostPosted: Sat Apr 26, 2003 11:08 am   Post subject: (No subject)

Toggle's dirX

not true = false
not false = true
therefor, not dirX = true if dirX = false, and vise versa
void




PostPosted: 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
Tony




PostPosted: Thu May 01, 2003 5:51 pm   Post subject: (No 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
Latest from compsci.ca/blog: Tony's programming blog. DWITE - a programming contest.
Homer_simpson




PostPosted: Thu May 01, 2003 6:27 pm   Post subject: (No 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
Homer_simpson




PostPosted: Thu May 01, 2003 6:35 pm   Post subject: (No subject)

code:
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

here's another one that balls change direction when they hit eachother
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