' Spring 0.5
' Copyright (c) 2012 Nonki Takahashi. All rights reserved.
'
' History:
' 0.5 2012/10/15 Considered horizontal parameters. (JDR565-9)
' 0.42 2012/10/15 Minor change.
' 0.41 2012/10/15 Fixed to be worked on Silverlight. (JDR564-8)
' 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 0.5"
msg = " - Hit space key to start/pause, R key to restart, or Q key to quit."
GraphicsWindow.Title = title + msg
scale = 3139 ' [dot/m]
spring[1]["l"] = 0.05 ' spring length [m]
spring[1]["w"] = 0.006 ' spring width [m]
spring[1]["le"] = 0.006 ' spring edge length [m]
spring[1]["k"] = 20 ' spring constant [N/m]
spring[1]["xs"] = 0.1 ' stationary point from left [m]
spring[1]["ys"] = 0 ' stationary point from top [m]
spring[1]["a"] = 0 ' angle of spring [degree]
spring[1]["cl"] = spring[1]["l"] + 0.05 ' initial length of spring [m]
m = 0.01 ' mass of weight [kg]
d = 0.01 ' diameter of weight [m]
g = 9.8 ' acceleration of gravity [m/(s^2)]
x0 = spring[1]["xs"] ' initial center x of weight from left [m]
y0 = spring[1]["ys"] + spring[1]["cl"] + d / 2 ' initial center y of weight from top [m]
vx0 = 0.001 ' initial x velocity of weight [m/s]
vy0 = 0 ' initial y velocity of weight [m/s]
InitParam()
fps = 12 ' frame rate [FPS (frames per second)]
time = Math.Round(1000 / fps)
dt = time / 1000
While continue
If tick Then
Animation()
tick = "False"
ElseIf key = "Space" Then
If pause Then
pause = "False"
Timer.Resume()
Else
pause = "True"
Timer.Pause()
EndIf
key = ""
ElseIf key = "R" Then
InitParam()
ShowWeight()
key = ""
ElseIf key = "Q" Then
continue = "False"
Else
Program.Delay(time / 10)
EndIf
EndWhile
Sound.PlayClickAndWait()
Program.End()
Sub Animation
kx = spring[1]["k"] * Math.Sin(Math.GetRadians(spring[1]["a"]))
ky = spring[1]["k"] * Math.Cos(Math.GetRadians(spring[1]["a"]))
dvx = -(spring[1]["cl"] - spring[1]["l"]) * kx * dt
dvy = (m * g - (spring[1]["cl"] - spring[1]["l"]) * ky) * dt
vx = vx + dvx ' next x velocity of weight
vy = vy + dvy ' next y velocity of weight
dx = (2 * vx + dvx) * dt / 2
dy = (2 * vy + dvy) * dt / 2
x = x + dx ' next center x of weight
y = y + dy ' next center y of weight
Stack.PushValue("local", x)
Stack.PushValue("local", y)
_y = x - spring[1]["xs"]
x = y - spring[1]["ys"]
y = _y
Math_CartesianToPolar()
spring[1]["a"] = a
spring[1]["cl"] = r - d / 2 ' current length of spring
y = Stack.PopValue("local")
x = Stack.PopValue("local")
ShowWeight()
EndSub
Sub OnTick
tick = "True"
EndSub
Sub OnKeyDown
key = GraphicsWindow.LastKey
EndSub
Sub InitParam
x = x0 ' initial center x of weight
y = y0 ' initial center y of weight
vx = vx0 ' initial x velocity of weight
vy = vy0 ' initial y velocity of weight
EndSub
Sub InitWeight
url = "http://www.nonkit.com/smallbasic.files/spring.png"
img = ImageList.LoadImage(url)
spring[1]["spring"] = Shapes.AddImage(img)
spring[1]["ld"] = ImageList.GetHeightOfImage(img) ' spring length (without edges) [dot]
If spring[1]["ld"] < 1 Then ' patch to make it work on Silverlight
spring[1]["ld"] = 276
EndIf
param["y"] = spring[1]["ys"] + spring[1]["cl"] - spring[1]["le"] / 2
Shapes_CalcRotatePos()
Shapes.Move(spring[1]["edge1"], x * scale, (y - spring[1]["le"] / 2) * scale)
Shapes.Rotate(spring[1]["edge1"], -spring[1]["a"])
y = Stack.PopValue("local")
x = Stack.PopValue("local")
EndSub
Sub Math_CartesianToPolar
' Math | convert cartesian coodinate to polar coordinate
' param x, y - cartesian coordinate
' return r, a - polar coordinate
r = Math.SquareRoot(x * x + y * y)
If x = 0 And y > 0 Then
a = 90 ' [degree]
ElseIf x = 0 And y < 0 Then
a = -90
Else
a = Math.ArcTan(y / x) * 180 / Math.Pi
EndIf
If x < 0 Then
a = a + 180
ElseIf x > 0 And y < 0 Then
a = a + 360
EndIf
EndSub
Sub Shapes_CalcRotatePos
' Shapes | Calculate position for rotated shape
' param["x"], param["y"] - position of a shape
' param["width"], param["height"] - size of a shape
' param ["cx"], param["cy"] - center of shapes
' param ["angle"] - rotate angle
' return x, y - rotated position of a shape
_cx = param["x"] + param["width"] / 2
_cy = param["y"] + param["height"] / 2
x = _cx - param["cx"]
y = _cy - param["cy"]
Math_CartesianToPolar()
a = a + param["angle"]
x = r * Math.Cos(a * Math.Pi / 180)
y = r * Math.Sin(a * Math.Pi / 180)
_cx = x + param["cx"]
_cy = y + param["cy"]
x = _cx - param["width"] / 2
y = _cy - param["height"] / 2
EndSub
Program Listing: JDR564-9