Microsoft Small Basic

Program Listing: JDR564-6

List Program

' Spring 0.32
' Physics Challenge
' Copyright (c) 2012 Nonki Takahashi. All rights reserved.
'
' History:
' 0.32 2012/10/14 Work on the web too + restart option by GoToLoop. (JDR564-6)
' 0.31 2012/10/14 Minor change. (JDR564-2)
' 0.3 2012/10/14 Changed to use image. (JDR564-1)
' 0.2 2012/10/13 Timer event mod by GoToLoop. (JDR564-0)
' 0.1 2012/10/13 Created. (JDR564)
'
title = "Spring 0.32"
msg = " - Hit start/pause, restart, any other key quit."
GraphicsWindow.Title = title + msg

scale = 3139 ' [dot/m]

l = .06 ' spring length [m]
w = .006 ' spring width [m]
le = .006 ' spring edge length [m]
k = 20 ' spring constant [N/m]
m = .01 ' mass of weight [kg]
d = .01 ' diameter of weight [m]
g = 9.8 ' acceleration of gravity [m/(s^2)]
xs = .1 ' stationary point from left [m]
ys = 0 ' stationary point from top [m]

x0 = xs - d/2
y0 = ys + l
y = y0 + l ' initial position of weight
v0 = 0
v = v0 ' initial velocity of weight

fps = 12 ' frame rate [FPS (frames per second)]
time = Math.Round(1000 / fps)
dt = time / 1000

isLocal = "False"

InitWeight()
Animation()

Timer.Tick = Animation
Timer.Interval = time
Timer.Pause()
isPaused = "True"

GraphicsWindow.KeyDown = Keyboard
GraphicsWindow.MouseDown = Pause

Sub Animation

ShowWeight()

dv = (m*g - (y - y0) * k) * dt
v = v + dv
dy = (2*v + dv) * dt/2
y = y + dy

EndSub

Sub InitWeight

If isLocal Then
path = Program.Directory + "\"
Else
path = "http://www.nonkit.com/smallbasic.files/"
EndIf

img = ImageList.LoadImage(path + "spring.png")
ld = ImageList.GetHeightOfImage(img) ' spring length (without edges) [dot]

If ld < 1 Then ' Patch to make it work on the web!
ld = 276
spring = Shapes.AddImage(path + "spring.png")
Else
spring = Shapes.AddImage(img)
EndIf

GraphicsWindow.PenColor = "DimGray"
edge0 = Shapes.AddLine(0,0 0,le*scale)
edge1 = Shapes.AddLine(0,0 0,le*scale)

GraphicsWindow.PenWidth = 0
GraphicsWindow.BrushColor = "Black"
weight = Shapes.AddEllipse(d*scale, d*scale)

Shapes.Move(edge0 xs*scale,ys*scale)

EndSub

Sub ShowWeight

Shapes.Move(weight x0*scale,y*scale)

Shapes.Move(spring (xs - w/2) * scale, ((y - y0 + l - 2*le) / 2 + le + ys) * scale - ld/2)
Shapes.Zoom(spring 1, (y - y0 + l - 2*le) * scale/ld)

Shapes.Move(edge1 xs*scale, (y - le + ys) * scale)

EndSub

Sub Keyboard

key = GraphicsWindow.LastKey

If key = "Space" Then
Pause()
ElseIf key = "Return" Then
Reset()
Else
Sound.PlayClickAndWait()
Program.End()
EndIf

EndSub

Sub Pause

If isPaused Then
isPaused = "False"
Timer.Resume()
Else
isPaused = "True"
Timer.Pause()
EndIf

EndSub

Sub Reset

v = v0
y = y0 + l

EndSub