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Sample of the Week, II

This week's featured sample comes from Jeff Sidlosky. It is a star field simulation - you know the one where it appears like you're moving fast through space, with stars whizzing past you.

 ' Star-field simulation
Initialize()   
Main()   
  
Sub Initialize   
    GraphicsWindow.Title = "Super Star Field!"  
    GraphicsWindow.Width = 640   
    GraphicsWindow.Height = 480   
    GraphicsWindow.BackgroundColor = "black"  
    GraphicsWindow.PenWidth = 0   
    GraphicsWindow.Show()   
       
    num_stars = 200   
       
    For index = 0 To num_stars   
        NewStar()   
    EndFor   
EndSub   
  
Sub NewStar   
    Array.SetValue("star_x", index, Math.GetRandomNumber(100) - 50)   
    Array.SetValue("star_y", index, Math.GetRandomNumber(100) - 50)   
       
    ' Pick a random z depth   
    z = (Math.GetRandomNumber(50) / 100) + 0.50   
       
    Array.SetValue("star_z", index, z)   
       
    ' Start with a dark color and save our shape   
    GraphicsWindow.BrushColor = "DimGray"  
    Array.SetValue("star_shape", index, GraphicsWindow.AddRectangle(2, 2))   
    Array.SetValue("star_color", index, 0)   
EndSub   
  
Sub Update   
    For index = 0 To num_stars   
        z = Array.GetValue("star_z", index)         
        x = (Array.GetValue("star_x", index) / z) + 320   
        y = (Array.GetValue("star_y", index) / z) + 240   
        shape = Array.GetValue("star_shape", index)   
           
        ' Next z position   
        z = z - 0.02   
           
        If(x < 0 Or x > 639 Or y < 0 Or y > 479 Or z <= 0) Then  
            GraphicsWindow.RemoveShape(shape)   
            NewStar()   
        Else  
            ' Check if we should make the star brighter   
            If(z < 0.4) Then  
                If(Array.GetValue("star_color", index) = 0) Then  
                    GraphicsWindow.BrushColor = "White"  
                    GraphicsWindow.RemoveShape(shape)   
                    shape = GraphicsWindow.AddRectangle(2, 2)   
                    Array.SetValue("star_shape", index, shape)    
                    Array.SetValue("star_color", index, 1)   
                EndIf   
            EndIf   
               
            GraphicsWindow.MoveShape(shape, x, y)   
                
            Array.SetValue("star_z", index, z)           
        EndIf       
    EndFor   
EndSub   
  
Sub Main   
    ' Run forever   
    While(1 = 1)   
        Update()   
    EndWhile   
EndSub

And here's the screenshot! The picture really doesn't do justice. Try this program on your copy of Small Basic to experience the real deal.

Do you want your samples to be featured here? Post them in our forums and we'll pick one each week.

Comments

  • Anonymous
    November 17, 2008
    PingBack from http://blog.a-foton.ru/index.php/2008/11/17/sample-of-the-week-ii/

  • Anonymous
    November 24, 2008
    The comment has been removed

  • Anonymous
    October 22, 2009
    Please note that if you try this sample code in the latest Small Basic version, you will need to refactor it a little, since some of the methods previously contained in the GraphicsWindow class have been moved (and sometimes renamed) in the Shapes class.

  • Anonymous
    December 10, 2010
    Just tried the programe out, doesn't seem to work?

  • Anonymous
    December 20, 2013
    Try this... ' Star-field simulation Initialize()   Main()   Sub Initialize      GraphicsWindow.Title = "Super Star Field!"      GraphicsWindow.Width = 640      GraphicsWindow.Height = 480      GraphicsWindow.BackgroundColor = "black"      GraphicsWindow.PenWidth = 0      GraphicsWindow.Show()      num_stars = 200      For index = 0 To num_stars          NewStar()      EndFor   EndSub   Sub NewStar      Array.SetValue("star_x", index, Math.GetRandomNumber(100) - 50)      Array.SetValue("star_y", index, Math.GetRandomNumber(100) - 50)      ' Pick a random z depth      z = (Math.GetRandomNumber(50) / 100) + 0.50      Array.SetValue("star_z", index, z)      ' Start with a dark color and save our shape      GraphicsWindow.BrushColor = "DimGray"      Array.SetValue("star_shape", index, Shapes.AddRectangle(2, 2))      Array.SetValue("star_color", index, 0)   EndSub   Sub Update      For index = 0 To num_stars          z = Array.GetValue("star_z", index)                x = (Array.GetValue("star_x", index) / z) + 320          y = (Array.GetValue("star_y", index) / z) + 240          shape = Array.GetValue("star_shape", index)          ' Next z position          z = z - 0.02          If(x < 0 Or x > 639 Or y < 0 Or y > 479 Or z <= 0) Then              Shapes.Remove(shape)              NewStar()          Else              ' Check if we should make the star brighter              If(z < 0.4) Then                  If(Array.GetValue("star_color", index) = 0) Then                      GraphicsWindow.BrushColor = "White"                      Shapes.Remove(shape)                      shape = Shapes.AddRectangle(2, 2)                      Array.SetValue("star_shape", index, shape)                        Array.SetValue("star_color", index, 1)                  EndIf              EndIf              Shapes.Move(shape, x, y)              Array.SetValue("star_z", index, z)                  EndIf          EndFor   EndSub   Sub Main      ' Run forever      While(1 = 1)          Update()      EndWhile   EndSub  

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