Monkey-X - Path Following - code example

' Path following - from the book - ai for game developers
Import mojo

Class entity
    Field tilex:Int
    Field tiley:Int
    Field entwidth:Int
    Field entheight:Int
    Field tilewidth:Float
    Field tileheight:Float
    Field mapwidth:Int
    Field mapheight:Int    
    Field direction:Int=1 ' 1 is up, 2 is upright ect clockwise
    Method New()
        mapwidth = mypathfollowing.mapwidth
        mapheight = mypathfollowing.mapheight
        entwidth = mypathfollowing.tilewidth
        entheight = mypathfollowing.tileheight
        tilewidth = mypathfollowing.tilewidth
        tileheight = mypathfollowing.tileheight
        findstartpos        
    End Method
    Method update()
        ' terrain analysis
        ' here we check clockwise around the entity its position
        ' and fill the ta(terrainanalysis) array with 0 if there is no read there
        ' and 10 if there is a road
        Local ta:Int[] = New Int[9]
        ta[1] = mypathfollowing.map[tiley-1][tilex]
        ta[2] = mypathfollowing.map[tiley-1][tilex+1]
        ta[3] = mypathfollowing.map[tiley][tilex+1]
        ta[4] = mypathfollowing.map[tiley+1][tilex+1]
        ta[5] = mypathfollowing.map[tiley+1][tilex]
        ta[6] = mypathfollowing.map[tiley+1][tilex-1]
        ta[7] = mypathfollowing.map[tiley][tilex-1]
        ta[8] = mypathfollowing.map[tiley-1][tilex-1]
        For Local i = 1 To 8
            If ta[i] = 0 
                ta[i] = 0
            Else
                ta[i] = 10
            End If
        Next
        ' weighted direction analysis
        ' here we use the current direction and add
        ' up the current direction with 2 and left and
        ' right from there with +1 and the opposite
        ' direction of the entity direction -1        
        If direction = 1
            ta[1] += 2
            ta[2] += 1
            ta[8] += 1
            ta[5] -= 1
        End If
        If direction = 2
            ta[2] += 2
            ta[3] += 1
            ta[1] += 1
            ta[6] -= 1
        End If
        If direction = 3
            ta[3] += 2
            ta[4] += 1
            ta[2] += 1
            ta[7] -= 1
        End If
        If direction = 4
            ta[4] += 2
            ta[5] += 1
            ta[3] += 1
            ta[8] -= 1
        End If
        If direction = 5
            ta[5] += 2
            ta[6] += 1
            ta[4] += 1
            ta[1] -= 1
        End If
        If direction = 6
            ta[6] += 2
            ta[7] += 1
            ta[5] += 1
            ta[2] -= 1
        End If
        If direction = 7
            ta[7] += 2
            ta[8] += 1
            ta[6] += 1
            ta[3] -= 1
        End If
        If direction = 8
            ta[8] += 2
            ta[1] += 1
            ta[7] += 1
            ta[4] -= 1
        End If
        ' choosing direction
        ' here we get the highest weight to get the next direction
        Local maxterrain:Int
        Local maxindex:Int
        For Local i=1 To 8
            If ta[i] > maxterrain
                maxterrain = ta[i]
                maxindex = i
            End If
        Next
        ' update position
        ' here we use the new direction and move the entity and set
        ' the new or last direction
        If maxindex = 1
            direction = 1
            tiley -= 1
        End If
        If maxindex = 2
            direction = 2
            tilex += 1
            tiley -= 1
        End If
        If maxindex = 3
            direction = 3
            tilex += 1
        End If
        If maxindex = 4
            direction = 4
            tilex += 1
            tiley += 1
        End If
        If maxindex = 5
            direction = 5
            tiley += 1
        End If
        If maxindex = 6
            direction = 6
            tilex -= 1
            tiley += 1
        End If
        If maxindex = 7
            direction = 7
            tilex -= 1
        End If
        If maxindex = 8
            direction = 8
            tilex -= 1
            tiley -= 1
        End If
    End Method
    Method findstartpos()
        For Local y=0 Until mapheight
        For Local x=0 Until mapwidth
            If mypathfollowing.map[y][x] = 1
                tilex = x
                tiley = y
                Return
            End If
        Next
        Next
    End Method
    Method draw()
        SetColor 255,255,0
        DrawRect tilex*tilewidth,tiley*tileheight,entwidth,entheight
    End Method
End Class

Class pathfollowing
Global map:Int[][] = [
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0],
[0,0,0,0,0,0,0,1,1,1,1,1,1,0,0,0,0,0,0,0],
[0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0,0],
[0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0],
[0,0,1,1,1,1,1,0,0,0,0,1,1,1,1,1,1,1,0,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,1,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0],
[0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,1,1,1,0,0],
[0,0,1,1,1,1,1,0,0,0,0,0,0,0,0,1,1,1,0,0],
[0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0],
[0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0],
[0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0],
[0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]]    
Field screenwidth:Int
    Field screenheight:Int
    Field mapwidth:Int
    Field mapheight:Int
    Field tilewidth:Float
    Field tileheight:Float
    Method New(width:Int,height:Int)
        mapwidth = map.Length
        mapheight = map[0].Length
        screenwidth = width
        screenheight = height
        tilewidth = Float(screenwidth)/Float(mapwidth)
        tileheight = Float(screenheight)/Float(mapheight)
    End Method
    Method draw()
        SetColor 200,100,0
        For Local y = 0 Until mapheight
        For Local x = 0 Until mapwidth
            If map[y][x] = 1
                DrawRect     x*tilewidth,y*tileheight,
                            tilewidth+1,tileheight+1
            End If
        Next
        Next
    End Method
End Class

Global mypathfollowing:pathfollowing
Global myentity:entity

Class MyGame Extends App
    Method OnCreate()
        SetUpdateRate(5)
        mypathfollowing = New pathfollowing(DeviceWidth,DeviceHeight)
        myentity = New entity()
    End Method
    Method OnUpdate()        
        myentity.update
    End Method
    Method OnRender()
        Cls 0,0,0 
        mypathfollowing.draw
        myentity.draw
        SetColor 255,255,255
        DrawText "Monkey-X - Path Following Example",10,10
    End Method
End Class


Function Main()
    New MyGame()
End Function