Sub AddWallToList
' param col, row - cell
' return nWalls - number of wall list
' return iWalls - index of wall list
' return colWalls[], rowWalls[] - wall list
' return colOpp[], rowOpp[] - cell list (on the opposite side)
For d = 0 To 3
colw = col + colAdj[d]
roww = row + rowAdj[d]
If 1 < colw And colw < cols2 And 1 < roww And roww < rows2 And cell[colw][roww] = 1 Then
i = colw + (roww - 1) * cols2
' find i in wall list
FindWallInList()
If i = iFound Then ' found
' remove the wall
nWalls = nWalls - 1
iWalls[iPrev] = iWalls[iFound]
Else
' add the wall to wall list
nWalls = nWalls + 1
iNext = iWalls[0]
iWalls[0] = i
iWalls[i] = iNext
colWall[i] = colw ' wall
rowWall[i] = roww
colOpp[i] = colw + colAdj[d] ' cell on the opposite side
rowOpp[i] = roww + rowAdj[d]
EndIf
EndIf
EndFor
EndSub
Sub ClearMaze
' param x0, y0
' param cols, rows
' param width
GraphicsWindow.BrushColor = "Green"
GraphicsWindow.FillRectangle(x0, y0, width * cols, width * rows)
GraphicsWindow.BrushColor = colorPassage
col0 = cols 'Math.GetRandomNumber(cols) ' start cell of maze generate
row0 = 1 'Math.GetRandomNumber(rows)
x = x0 + (col0 - 1) * width
y = y0 + (row0 - 1) * width
GraphicsWindow.FillRectangle(x + (pen / 2), y + (pen / 2), width - pen, width - pen) ' start cell
GraphicsWindow.PenColor = colorWall
GraphicsWindow.DrawRectangle(x0, y0, width * cols, width * rows)
y1 = y0 + width * rows
For col = 1 To cols - 1
x = x0 + width * col
GraphicsWindow.DrawLine(x, y0, x, y1)
EndFor
x1 = x0 + width * cols
For row = 1 To rows - 1
y = y0 + width * row
GraphicsWindow.DrawLine(x0, y, x1, y)
EndFor
For row = 1 To rows2
For col = 1 To cols2
cell[col][row] = 1
EndFor
EndFor
cell[2 * col0][2 * row0] = 0 ' generate start
nWalls = 0
EndSub
Sub DumpMaze
buf = ""
For row = 1 To rows2
For col = 1 To cols2
If cell[col][row] = 1 Then
buf = buf + "■"
Else
buf = buf + " "
EndIf
EndFor
buf = buf + Text.GetCharacter(13) + Text.GetCharacter(10)
EndFor
TextWindow.Write(buf)
EndSub
Sub FindPassage
xt = Turtle.X
yt = Turtle.Y
back = Math.Remainder(Turtle.Angle + 180, 360)
Turtle.TurnRight()
nturn = 1
IsWall()
If bWall Then
Turtle.TurnLeft()
nturn = nturn - 1
IsWall()
EndIf
While bWall
Turtle.TurnRight()
nturn = nturn + 1
IsWall()
EndWhile
EndSub
Sub FindWallInList
' param i - index to remove of wall list
' return iPrev - previous index of i
' return iFound - i if found
iFound = 0
c = 1
While i <> iFound And c <= nWalls
c = c + 1
iPrev = iFound
iFound = iWalls[iFound]
EndWhile
EndSub
Sub GenerateMaze
' Generate maze with randomized Prim's algorithm
' param x0, y0
' param cols, rows
' param width
' 1. Start with a grid full of walls.
ClearMaze()
' 2. Pick a cell, mark it as part of the maze. Add the walls of the cell to the wall list.
col = 2 * col0
row = 2 * row0
AddWallToList()
' 3. While there are walls in the list:
While nWalls > 0
' 1. Pick a random wall from the list. If the cell on the opposite side isn't in the maze yet:
GetRandomIndex()
col = colOpp[i]
row = rowOpp[i]
If cell[col][row] = 1 Then
' 1. Make the wall a passage and mark the cell on the opposite side as part of the maze.
colw = colWall[i]
roww = rowWall[i]
RemoveWallFromList()
cell[colw][roww] = 0 ' wall
cell[col][row] = 0 ' cell on the opposite side
KnockDownWall()
If debug Then
Program.Delay(20)
EndIf
' 2. Add the neighboring walls of the cell to the wall list.
AddWallToList()
If debug Then
TextWindow.WriteLine("iWalls=" + iWalls)
TextWindow.Write("nWalls=" + nWalls)
TextWindow.Read()
EndIf
Else
' 2. If the cell on the opposite side already was in the maze, remove the wall from the list.
RemoveWallFromList()
EndIf
EndWhile
DrawGoal()
EndSub
Sub GetRandomIndex
' get random index of wall list
' return i - index
n = Math.GetRandomNumber(nWalls)
i = 0
For c = 1 To n
i = iWalls[i]
EndFor
EndSub
Sub IsWall
' param xt - x coodinate of Turtle
' param yt - y coodinate of Turtle
' return a - angle of Turtle
' return bWall - "True" if wall is in front of Turtle
a = Math.Remainder(Turtle.Angle, 360)
If a = back And nturn <= 2 Then
bWall = "True"
Else
x = xt + (width / 2) * Math.Sin(a / 180 * Math.Pi)
y = yt - (width / 2) * Math.Cos(a / 180 * Math.Pi)
color = GraphicsWindow.GetPixel(x, y)
If color = colorWall Then
bWall = "True"
Else
bWall = "False"
EndIf
EndIF
EndSub
Sub Move
' param a - angle of Turtle
' return pos - Turtle position
' return moves - number of moves
Turtle.PenDown()
GraphicsWindow.PenColor = colorRoute
GraphicsWindow.PenWidth = 2
Turtle.Move(width)
If a = 0 Then
pos = pos - (cols + 1)
ElseIf a = 90 Then
pos = pos + 1
ElseIf a = 180 Then
pos = pos + (cols + 1)
ElseIf a = 270 Then
pos = pos - 1
EndIf
moves = moves + 1
EndSub
Sub OnButtonClicked
bIdle = "False"
EndSub
Sub RemoveWallFromList
' param i - index to remove of wall list
' param wall[] - wall list
' param nWalls - number of wall list
FindWallInList()
If i = iFound Then ' found
iWalls[iPrev] = iWalls[iFound]
iWalls[iFound] = ""
nWalls = nWalls - 1
EndIf
EndSub
Program Listing: PNC833