Brute Force Pathfinding

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SoCoder -> Snippet Home -> AI and Movement

Pakz	Created : 06 January 2018 Edited : 06 January 2018 Language : Monkey2 Brute Force Pathfinding Create a path by doing all combinations(grow number) Emscripten demo
#Import "<std>" #Import "<mojo>" Using std.. Using mojo.. ' Large maps require super CPU!! (2020) Global mapwidth:Int=8 Global mapheight:Int=8 Global tilewidth:Int,tileheight:Int Global maxpathlen:Int=25 Global path:Int[] = New Int[maxpathlen] Global map:Int[,] Class MyWindow Extends Window Field sx:Int,sy:Int Field ex:Int,ey:Int Field ms:Int Field pathed:Bool=False Method New() tilewidth=Width/mapwidth tileheight=Height/mapheight sx = 2 sy = 2 ex = 7 ey = 7 map = New int[mapwidth,mapheight] End Method Method OnRender( canvas:Canvas ) Override App.RequestRender() ' Activate this method drawgrid(canvas) If pathed = True Then drawpath(canvas) If Keyboard.KeyReleased(Key.Space) path = New Int[maxpathlen] ms = Millisecs() Repeat Local s:Bool=pathfound() If s=True Then Print Millisecs()-ms pathed = True Exit End If incpath() ' timeout after xxxxx millisecs If ms+10000<Millisecs() Then Print "failed - timeout" pathed=False Exit End If Forever End If Local tx:Int=Mouse.X/tilewidth Local ty:Int=Mouse.Y/tileheight If Mouse.ButtonReleased(MouseButton.Middle) If tx=sx And ty=sy Or tx=ex And ty=sy Else If map[tx,ty] = 1 map[tx,ty] = 0 Else map[tx,ty] = 1 End If End if End If If Mouse.ButtonReleased(MouseButton.Left) If map[tx,ty] = 0 sx = tx sy = ty pathed=False End If End If If Mouse.ButtonReleased(MouseButton.Right) If map[tx,ty] = 0 ex = tx ey = ty pathed=False End If End If canvas.Color = Color.Black canvas.DrawText("LMB(start)/RMB(end)/SPACE(findpath)MMB(wall)",0,0) If Keyboard.KeyReleased(Key.Escape) Then App.Terminate() End Method Method pathfound:Bool() Local cx:Int=sx Local cy:Int=sy For Local i:Int=maxpathlen-1 Until 0 Step -1 Select path[i] Case 0'up cy-=1 Case 1'right cx+=1 Case 2'down cy+=1 Case 3'left cx-=1 End Select If cx<0 Or cx>=mapwidth Or cy<0 Or cy>=mapheight Then Return False If map[cx,cy] = 1 Then Return False If ex = cx And ey = cy Then Return True Endif Next Return False End Method Method incpath() path[maxpathlen-1]+=1 For Local i:Int=maxpathlen-1 Until 1 Step-1 If path[i] > 3 Then path[i] = 0 path[i-1] += 1 Endif Next End Method Method drawgrid(canvas:Canvas) For Local y:Int=0 Until mapheight For Local x:Int=0 Until mapwidth canvas.Color = Color.Black canvas.DrawRect(xtilewidth,ytileheight,tilewidth,tileheight) canvas.Color = Color.White canvas.DrawRect(xtilewidth+1,ytileheight+1,tilewidth-1,tileheight-1) If map[x,y] = 1 Then canvas.Color = Color.Magenta canvas.DrawRect(xtilewidth,ytileheight,tilewidth,tileheight) End If If x=sx And y = sy Then canvas.Color = Color.Green canvas.DrawRect(xtilewidth,ytileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("start LMB",xtilewidth,ytileheight) End If If x=ex And y = ey Then canvas.Color = Color.Yellow canvas.DrawRect(xtilewidth,ytileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("end RMB",xtilewidth,ytileheight) End If Next Next End Method Method drawpath(canvas:Canvas) canvas.Color = Color.Red Local cx:Int=sx Local cy:Int=sy For Local i:Int=maxpathlen-1 Until 0 Step -1 Select path[i] Case 0'up cy-=1 Case 1'right cx+=1 Case 2'down cy+=1 Case 3'left cx-=1 End Select canvas.DrawCircle(cxtilewidth+tilewidth/2,cytileheight+tileheight/2,10) If ex = cx And ey = cy Then Return Endif Next End Method End Class Function Main() New AppInstance New MyWindow App.Run() End Function --v
Latest Update I made this pathfinder to see if it was simple to do. What it does is add up a string of numbers(directions). In a function I add up one movement possibility to the string. So it starts with a string size of 1. The value there is 0(up) to 3(left) by adding up one movement you will find the shortest path to the destination. Counting your way there. It is super slow on larger maps, but on smaller maps a path is found in a instant.

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