Sub CalcCarPos
' param i - car index
' param car[i]["x1"], car[i]["y1"] - car head position
' return car[i]["x2"], car[i]["y2"] - car tail position
' return car[i]["xc"], car[i]["yc"] - car center position
' return car[i]["xj"], car[i]["yj"] - joint center position (if not last car)
' return car[i+1]["x1"], car[i+1]["y1"] - next car hed position (if not last car)
car_i = car[i]
x1 = car_i["x1"] ' car head
y1 = car_i["y1"]
len = carLength
CalcNextPos()
car_i["x2"] = x2 ' car end
car_i["y2"] = y2
car_i["xc"] = xc ' car center
car_i["yc"] = yc
car_i["ac"] = a ' car angle
If i < cars Then
x1 = car_i["x2"]
y1 = car_i["y2"]
len = jointLength
p0 = p1
CalcNextPos()
car_i1 = car[i + 1]
car_i1["x1"] = x2 ' next car head
car_i1["y1"] = y2
car[i + 1] = car_i1
car_i["xj"] = xc ' joint center
car_i["yj"] = yc
car_i["aj"] = a ' joint angle
EndIf
car[i] = car_i
EndSub
Sub CalcNextPos
' param p0 - rail position index
' param r0 - ratio between p0 and p0-1
' param x1, y1 - start position
' param len - length
' return x2, y2 - end position
' return xc, yc - center position
' return a - angle
' return p1 - end rail position index
' return r1 - ratio between p1 and p2
p0_1 = p0 - 1
If p0_1 <= 0 Then
p0_1 = numRails
EndIf
rails_p0 = rails[p0]
rails_p0_1 = rails[p0_1]
x0 = rails_p0["x"] + r0 * (rails_p0_1["x"] - rails_p0["x"])
y0 = rails_p0["y"] + r0 * (rails_p0_1["y"] - rails_p0["y"])
p2 = p0_1
rails_p2 = rails[p2]
d = Math.SquareRoot(Math.Power(rails_p2["x"] - x0, 2) + Math.Power(rails_p2["y"] - y0, 2))
While d < len
p2 = p2 - 1
If p2 <= 0 Then
p2 = numRails
EndIf
rails_p2 = rails[p2]
d = Math.SquareRoot(Math.Power(rails_p2["x"] - x0, 2) + Math.Power(rails_p2["y"] - y0, 2))
EndWhile
p1 = p2 + 1
If numRails < p1 Then
p1 = 1
EndIf
If p1 = p0 Then
r1 = r0
Else
r1 = 0
EndIf
FindPos()
xc = (x1 + x2) / 2
yc = (y1 + y2) / 2
x = x2 - x1
y = y2 - y1
Math_CartesianToPolar()
r0 = r1
p0 = p1
EndSub
Sub DrawTrain
' param cars - number of cars
' param pos - rail position index
rails_pos = rails[pos]
car_1 = car[1]
car_1["x1"] = rails_pos["x"]
car_1["y1"] = rails_pos["y"]
car[1] = car_1
r0 = 0
p0 = pos
For i = 1 To cars
GraphicsWindow.PenWidth = 0
GraphicsWindow.BrushColor = carColor
car_i = car[i]
If car_i["obj"] = "" Then
car_i["obj"] = Shapes.AddRectangle(carLength, carWidth)
car[i] = car_i
EndIf
CalcCarPos()
Shapes.Move(car_i["obj"], car_i["xc"] - carLength / 2, car_i["yc"] - carWidth / 2)
Shapes.Rotate(car_i["obj"], car_i["ac"])
If i < cars Then
GraphicsWindow.PenWidth = jointWidth
GraphicsWindow.PenColor = jointColor
If joint[i] = "" Then
joint[i] = Shapes.AddLine(0, 0, jointLength, 0)
EndIf
Shapes.Move(joint[i], car_i["xj"] - jointLength / 2, car_i["yj"] - jointWidth / 2)
Shapes.Rotate(joint[i], car_i["aj"])
EndIf
EndFor
EndSub
Sub FindPos
' param x0, y0 - start position
' param len - length
' param p1 - position 1
' param p2 - position 2
' param r1 - ratio between pos and pos+1
' return x2, y2 - found position
' return r1 - found ratio between p1 and p2
r2 = 1
While 0.1 < (r2 - r1)
r = (r1 + r2) / 2
rails_p1 = rails[p1]
rails_p2 = rails[p2]
x2 = rails_p1["x"] + r * (rails_p2["x"] - rails_p1["x"])
y2 = rails_p1["y"] + r * (rails_p2["y"] - rails_p1["y"])
d = Math.SquareRoot(Math.Power(x2 - x0, 2) + Math.Power(y2 - y0, 2))
If d < len Then
r1 = r
Else
r2 = r
EndIf
EndWhile
EndSub
Sub Init
GraphicsWindow.Width = 600
GraphicsWindow.Height = 400
carLength = 40
carWidth = carLength / 5
carColor = "YellowGreen"
railColor = "Silver"
railLength = 10
jointLength = 4
jointWidth = 2
jointColor = "Gray"
x = 310
y = 90
For pos = 1 To 11
rails_pos["x"] = x
rails_pos["y"] = y
rails[pos] = rails_pos
x = x - railLength
EndFor
a = 0
For pos = 12 To 47
rails_pos["x"] = x
rails_pos["y"] = y
rails[pos] = rails_pos
_a = Math.GetRadians(a)
x = x - railLength * Math.Cos(_a)
y = y + railLength * Math.Sin(_a)
a = a + 5
EndFor
For pos = 48 To 68
rails_pos["x"] = x
rails_pos["y"] = y
rails[pos] = rails_pos
x = x + railLength
EndFor
For pos = 69 To 104
rails_pos["x"] = x
rails_pos["y"] = y
rails[pos] = rails_pos
_a = Math.GetRadians(a)
x = x - railLength * Math.Cos(_a)
y = y + railLength * Math.Sin(_a)
a = a + 5
EndFor
For pos = 105 To 115
rails_pos["x"] = x
rails_pos["y"] = y
rails[pos] = rails_pos
x = x - railLength
EndFor
numRails = pos - 1
EndSub
Sub Run
For pos = 1 To numRails
DrawTrain()
Program.Delay(200)
EndFor
EndSub
Sub Math_CartesianToPolar
' Math | convert Cartesian coodinate to polar coordinate
' param x, y - Cartesian coordinate
' return r, a - polar Coordinate (0<=a<360)
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
ElseIf x = 0 And y = 0 Then
a = 0
Else
a = Math.ArcTan(y / x) * 180 / Math.Pi
EndIf
' at this point -90<=a<=90
If x < 0 Then
a = a + 180
ElseIf x >= 0 And y < 0 Then
a = a + 360
EndIf
' at this point 0<=a<360
EndSub
Program Listing: CKS893