Bouncing Ball

Question

Hello! Can anyone tell me how to make a ball bounce in the GraphicsWindow?

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-Noah J. Buscher "Nothing is Impossible Until Proven Impossible."

Answer 1

Hi Noah,

This is definately possible and has been done before using SB 0.3 by Vijaye Raji (The creator of SB).

Here is his code

orbImage = ImageList.LoadImage("http://smallbasic.com/drop/orb.png")
orb = Shapes.AddImage(orbImage)
width = ImageList.GetWidthOfImage(orbImage)
height = ImageList.GetHeightOfImage(orbImage)
x = 320 - height / 2
startY = 0
w = GraphicsWindow.Width
h = GraphicsWindow.Height
GraphicsWindow.BackgroundColor = "Black"
GraphicsWindow.FillRectangle(0, h, w + 60, 60)
GraphicsWindow.CanResize = "False"
Shapes.Move(orb, x, y)
gravity = 9.8
elasticity = 0.7
direction = 1
time = 0
u = 0
v = 0
GraphicsWindow.MouseDown = OnMouseDown
running = 1
While "True"
  If running = 1 Then
    Shapes.Move(orb, x, y)
    time = time + 0.1
    v = u + gravity * time * direction
    y = startY + (u + v) * time * direction / 2
    
    If y > h - height Then
      y = h - height
      time = 0
      direction = -1
      u = v * elasticity
      startY = y
      
      If u < 4 Then
        running = 0
      EndIf
    EndIf
    
    If direction = -1 And Math.Abs(v) < 1 Then
      time = 0
      direction = 1
      startY = y
      u = 0
    EndIf
  EndIf
  
  Program.Delay(10)
EndWhile
GraphicsWindow.ShowMessage("End", u)
Sub OnMouseDown
  x = GraphicsWindow.MouseX - width / 2
  y = GraphicsWindow.MouseY - height / 2
  startY = y
  u = 0
  v = 0
  time = 0
  direction = 1
  running = 1
EndSub

http://social.msdn.microsoft.com/Forums/en-IE/smallbasic/thread/90c2ed47-7a7d-4093-b57b-0023b7dd3b6c

Please also take alook into Litdev's Box2D port for SB I think it may be easier and faster.

Answer 2

Looks good, awesome! But... not exactly what I was looking for. I am wondering how to make a ball bounce and when it hits a wall, bounce off. I have seen it in some brick breaker games, but I don't know the exact code. Sorry!

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-Noah J. Buscher "Nothing is Impossible Until Proven Impossible."

Answer 3

Oh sorry your original post wasn't very clear.

I believe it's velocity you are refering to. Now I am not very good with physics but here is a simple example for you to look at. Maybe a more experienced member can provide addtional help regarding this subject.

GraphicsWindow.Height = 400
GraphicsWindow.Width = 400
GraphicsWindow.CanResize = "FALSE"

ballx = 100
bally = 100
velx = 1.1
vely = 1.5
ball = Shapes.AddEllipse(20, 20)
Shapes.Move(ball, ballx, bally)
While "True"
  ballx = ballx + velx
  bally = bally + vely
  
  If bally > 380 Then
    vely = -1.5
  ElseIf bally < 0 then
    vely = 1.5
  EndIf
  
  If ballx > 380 Then
    velx = -1.1
  ElseIf ballx < 0 then
    velx = 1.1
  EndIf
  
  Shapes.Move(ball, ballx, bally)
  Program.Delay(10)
EndWhile

Answer 4

Here is a simple way...

Ball = Shapes.AddEllipse(10,10)
x = 30
y = 50
dx = 1
dy = 1
While 1 = 1
  Program.Delay(5)
  x = x + dx
  y = y + dy
  Shapes.Move(Ball,x,y)
  If y > GraphicsWindow.Height - 10 Or y < 0 Then
    dy = - dy
  EndIf
  If x > GraphicsWindow.Width - 10 Or x < 0 Then
    dx = - dx
  EndIf
  EndWhile

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One thing that is impossible is impossible no matter if it is proven so first.

Answer 5

I never thought 'OR' and 'AND' was native SB keywords.

Answer 6

They are. and they are very usefull

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One thing that is impossible is impossible no matter if it is proven so first.

Answer 7

Yes they are usefull.

The reason I thought they never existed in SB was due to the intellisence not showing them unless IF has been typed. Learn something new everyday :)

Answer 8

Thanks!

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-Noah J. Buscher "Nothing is Impossible Until Proven Impossible."