Monkey-X - Flow Fields - Lines - code example

Import mojo

Class flowfield
    Field mapwidth:Int,mapheight:Int
    Field tilewidth:Float,tileheight:Float
    Field screenwidth:Int,screenheight:Int
    Field map:Int[][]
    Field flowlinestartx:Int
    Field flowlinestarty:Int

    Method New(screenwidth:Int,screenheight:Int,mapwidth:Int,mapheight:Int)
        Self.screenwidth = screenwidth
        Self.screenheight = screenheight
        Self.tilewidth = Float(screenwidth)/Float(mapwidth)
        Self.tileheight = Float(screenheight)/Float(mapheight)
        Self.mapwidth = mapwidth
        Self.mapheight = mapheight
        ' make a array
        map = New Int[mapwidth][]
        For Local i = 0 Until mapwidth
            map[i] = New Int[mapheight]
        Next    
        ' -1 if no direction
        For Local y:=0 Until mapheight
        For Local x:=0 Until mapheight
            map[x][y] = -1
        Next
        Next
        '
        ' Here we create a number of points
        ' with which we draw the lines in between.
        '
        Seed = GetDate[5]
        Local lastx:Int=Rnd(2,mapwidth-2)
        Local lasty:Int=Rnd(2,mapheight-2)
        flowlinestartx = lastx
        flowlinestarty = lasty
        For Local i:=0 Until 5
            Local newx:Int=Rnd(2,mapwidth-2)
            Local newy:Int=Rnd(2,mapheight-2)
            flowline(lastx,lasty,newx,newy)
            lastx=newx
            lasty=newy
        Next
    End Method
    ' Make a flowfield(line) between two points
    Method flowline(x1:Int,y1:Int,x2:Int,y2:Int)
        Local dx:Int, dy:Int, sx:Int, sy:Int, e:Int
          dx = Abs(x2 - x1)
          sx = -1
          If x1 < x2 Then sx = 1      
          dy = Abs(y2 - y1)
          sy = -1
          If y1 < y2 Then sy = 1
          If dx < dy Then 
             e = dx / 2 
          Else 
             e = dy / 2          
          End If
          Local exitloop:Bool=False
          While exitloop = False
            'SetColor 255,255,255
            'DrawPoint x1,y1
            If x1 = x2 
                If y1 = y2
                    exitloop = True
                End If
            End If
            For Local y:=-1 To 1
            For Local x:=-1 To 1
                map[x1+x][y1+y] = pointto(x1+x,y1+y,x1,y1)
            Next
            Next
            map[x1][y1] = pointto(x1,y1,x2,y2)
            If dx > dy Then
                x1 += sx ; e -= dy 
                  If e < 0 Then e += dx ; y1 += sy
            Else
                y1 += sy ; e -= dx 
                If e < 0 Then e += dy ; x1 += sx
            Endif
          Wend
     End Method
    ' point the flow field direction to the x2,y2 from x1,y1
     Function pointto:Int(x1:Int,y1:Int,x2:Int,y2:Int)
        Local nd:Int=-1
        If x1<x2 Then nd=0
        If x1>x2 Then nd=4
        If y1<y2 Then nd=2
        If y1>y2 Then nd=6                    
        If x1<x2 And y1<y2 Then nd=1
        If x1>x2 And y1<y2 Then nd=3
        If x1<x2 And y1>y2 Then nd=7
        If x1>x2 And y1>y2 Then nd=5
        Return nd
     End Function

    Method draw()
        SetColor 255,255,255
        For Local y:=0 Until mapheight
        For Local x:=0 Until mapwidth
            Local direction:Int = map[x][y]
            If direction=-1 Then Continue
            Local x1:Float=Float(x)*tilewidth+tilewidth/2
            Local y1:Float=Float(y)*tileheight+tileheight/2
            Local ang:Int= (360/8*direction)
            Local x2:Float=x1+(Cos(ang)*tilewidth/2)
            Local y2:Float=y1+(Sin(ang)*tileheight/2)        
            Local x3:Float=x1+(Cos(ang+150)*tilewidth/4)
            Local y3:Float=y1+(Sin(ang+150)*tileheight/4)        
            Local x4:Float=x1+(Cos(ang-150)*tilewidth/4)
            Local y4:Float=y1+(Sin(ang-150)*tileheight/4)        
            
            DrawPoly([x2,y2,x3,y3,x4,y4])
        Next
        Next
    End Method
End Class

Class MyGame Extends App
    Field myflowfield:flowfield
    Field alienx:Int=200,alieny:Int=200
    Field lastx:Int,lasty:Int
    Method OnCreate()
        SetUpdateRate(60)
        myflowfield = New flowfield(DeviceWidth(),DeviceHeight(),50,50)
        alienx = myflowfield.flowlinestartx * myflowfield.tilewidth
        alieny = myflowfield.flowlinestarty * myflowfield.tileheight
    End Method
    Method OnUpdate()    
        Local d:Int=myflowfield.map[alienx/myflowfield.tilewidth][alieny/myflowfield.tileheight]
        ' Move the alien based on the flowfield array's direction 0=right 1=rightdown 7=rightup
        Select d
            Case 0
            alienx+=1
            Case 1
            alienx+=1;alieny+=1
            Case 2
            alieny+=1
            Case 3
            alienx-=1
            alieny+=1
            Case 4
            alienx-=1
            Case 5
            alienx-=1
            alieny-=1
            Case 6
            alieny-=1
            Case 7
            alieny-=1
            alienx+=1
        End Select
    
        ' stay inside array(screen)
        If alienx+10>DeviceWidth() Then alienx = DeviceWidth()-10
        If alienx-10<0 Then alienx = 10
        If alieny+10>DeviceHeight() Then alieny = DeviceHeight()-10
        If alieny-10<0 Then alieny = 10

        ' if we press the left mouse then move the alien to mouse position
        If MouseHit(MOUSE_LEFT) Then
            alienx = MouseX
            alieny = MouseY
        End If
        
        ' if pressed space or no move by alien then new flowfield
        If KeyHit(KEY_SPACE) Or lastx = alienx And lasty = alieny
            myflowfield = New flowfield(DeviceWidth(),DeviceHeight(),50,50)
            alienx = myflowfield.flowlinestartx * myflowfield.tilewidth
            alieny = myflowfield.flowlinestarty * myflowfield.tileheight
        End If    
        
        lastx = alienx
        lasty = alieny
    End Method
    Method OnRender()
        Cls 0,0,0 
        SetColor 255,255,255
        myflowfield.draw()
        SetColor 255,0,0
        DrawCircle(alienx,alieny,20)
        SetColor 255,255,255
        DrawText("Flow Fields (lines)- Press lmb to place alien - space new map.",0,0)
    End Method
End Class

Function rectsoverlap:Bool(x1:Int, y1:Int, w1:Int, h1:Int, x2:Int, y2:Int, w2:Int, h2:Int)
    If x1 >= (x2 + w2) Or (x1 + w1) <= x2 Then Return False
    If y1 >= (y2 + h2) Or (y1 + h1) <= y2 Then Return False
    Return True
End

Function Main()
    New MyGame()
End Function