Brute Force Pathfinding

[PakzParticipant]

I wanted to try and see if this would work.

What I did here is create a pathfinding routine that works by creating every possible path starting at size 0 growing until the path is found. Because it grows, the first valid path will be the shortest. It seems to work on my laptop on small maps. 8×8 size.

I find it difficult to explain how it works but maybe the code will speak for itself.

Monkey

#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] For Local i:Int=0 Until maxpathlen path[i]=-1 Next 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 Default'exit Return False 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(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.White canvas.DrawRect(x*tilewidth+1,y*tileheight+1,tilewidth-1,tileheight-1) If map[x,y] = 1 Then canvas.Color = Color.Magenta canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) End If If x=sx And y = sy Then canvas.Color = Color.Green canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("start LMB",x*tilewidth,y*tileheight) End If If x=ex And y = ey Then canvas.Color = Color.Yellow canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("end RMB",x*tilewidth,y*tileheight) 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(cx*tilewidth+tilewidth/2,cy*tileheight+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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187

#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] For Local i:Int=0 Until maxpathlen path[i]=-1 Next 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 Default'exit Return False 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(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.White canvas.DrawRect(x*tilewidth+1,y*tileheight+1,tilewidth-1,tileheight-1) If map[x,y] = 1 Then canvas.Color = Color.Magenta canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) End If If x=sx And y = sy Then canvas.Color = Color.Green canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("start LMB",x*tilewidth,y*tileheight) End If If x=ex And y = ey Then canvas.Color = Color.Yellow canvas.DrawRect(x*tilewidth,y*tileheight,tilewidth,tileheight) canvas.Color = Color.Red canvas.DrawText("end RMB",x*tilewidth,y*tileheight) 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(cx*tilewidth+tilewidth/2,cy*tileheight+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

 

Here a emscripten page showing the code.

https://cromdesi.home.xs4all.nl/emscripten/bruteforcepathfinding/Untitled1.html

[coconParticipant]

Good one, it can be combined it with my multi loops here, this will allow the CPU to rest a few times.

Multiple loops at the same time (fast and slow)

[Author]

Posts