procedure Gravity_Pull (XG, YG : int, var VX, VY : real4, G,
        X, Y : real4)
    if Y > YG then
        VY := VY - G
    else
        VY := VY + G
    end if
    % uncomment this section to allow the balls to orbit on the x-axis as well

    % if X > XG then
    %     VX := VX - G
    % else
    %     VX := VX + G
    % end if
    %
end Gravity_Pull


procedure Gravity_Fall (X, Y : real4, var VX, VY : real4, Ground : int,
        BF, G : real4)
    VY := VY - G
    if Y <= Ground then
        VY := - (VY / BF)
    end if
    if X > maxx or X < 1 then
        VX := -VX
    end if


end Gravity_Fall


procedure Wall_Bounce (X, Y : real4, var VX, VY : real4)
    if X < 1 or X > maxx then
        VX := -VX
    end if
    if Y < 1 or Y > maxy then
        VY := -VY
    end if
end Wall_Bounce
const NUM_OF_OBS := 400

type ORB_RECORD :
    record
        VX, VY,
            XW, YW : real4
    end record


type ORB_ARRAY : array 1 .. NUM_OF_OBS of ORB_RECORD

const G := .64         % gravity
const FORCE := 10         % the force given to the object when launched
% change these consts to change the colors of the
%projectiles
const C1 := 8
const LENGTH := 3
const C2 := 0

setscreen ("graphics:max,max,nobuttonbar,offscreenonly")

var XM, YM, Click : int
% var XW, YW, VY, VX : array 1 .. NUM_OF_OBS of real4
var Orbs : ORB_ARRAY
var Angle : real4
var Key : array char of boolean
var Clicked : boolean
var DropNum, FireCount : nat
var Water : real4
Water := 1
Angle := 0

for W : 1 .. NUM_OF_OBS
    Orbs (W).XW := Rand.Int (1, maxx)
    Orbs (W).YW := Rand.Int (1, maxy)
    Orbs (W).VY := 0
    Orbs (W).VX := 0
end for

Clicked := false



DropNum := 1
FireCount := 1
colorback (7)
loop

    cls
    drawfilloval (maxx div 2, maxy div 2, 50, 50, 0)
    Input.KeyDown (Key)
    mousewhere (XM, YM, Click)

    if Key (KEY_RIGHT_ARROW) then
        Angle := Angle + 1
    elsif
            Key (KEY_LEFT_ARROW) then
        Angle := Angle - 1
    end if
    if Angle > 360 then
        Angle := 0
    elsif Angle < 0 then
        Angle := 360
    end if

    if Click = 1 then
        Orbs (DropNum).XW := XM
        Orbs (DropNum).YW := YM

        Orbs (DropNum).VY := round (sind (Angle) * FORCE)
        Orbs (DropNum).VX := round (cosd (Angle) * FORCE)
        FireCount := 0
        if DropNum < NUM_OF_OBS then
            DropNum := DropNum + 1
        else
            DropNum := 1
        end if
        Clicked := true
    end if


    for W : 1 .. NUM_OF_OBS
        Orbs (W).XW := Orbs (W).XW + Orbs (W).VX
        Orbs (W).YW := Orbs (W).YW + Orbs (W).VY

        Wall_Bounce (Orbs (W).XW, Orbs (W).YW, Orbs (W).VX, Orbs (W).VY)
       
        % comment or uncomment the followning subprograms for
        % different gravity options
        Gravity_Pull (maxx div 2, maxy div 2, Orbs (W).VX, Orbs (W).VY,
            G, Orbs (W).XW, Orbs (W).YW)
        %Gravity_Fall (Orbs (W).XW, Orbs (W).YW, Orbs (W).VX, Orbs (W).VY,
        %  1, 1.5, G)
        drawfilloval (round (Orbs (W).XW - (Orbs (W).VX * LENGTH)),
            round (Orbs (W).YW - (Orbs (W).VY * LENGTH)),
            5, 5, 12)

        % bellow are some different options for drawing lines based on
        % the x/y cords
        %   drawline (1, round (Orbs (W).YW), maxx, round (Orbs (W).YW), 12)
        % drawline (round (Orbs (W).XW), 1, round (Orbs (W).XW), maxy, 12)

        % drawline (round (Orbs (W).XW), round (Orbs (W).YW), maxx div 2,
        %      maxy div 2, 9)

    end for


    drawline (XM, YM, XM + round (cosd (Angle) * 15),
        YM + round (sind (Angle) * 15), 12)
    drawfilloval (XM, YM, 5, 5, 12)
    put DropNum

    View.Update
end loop