Bitwise technique

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SoCoder -> Snippet Home -> Maps and Levels

Pakz	Created : 23 January 2019 Edited : 23 January 2019 Language : Monkey2 Bitwise technique Id System for neighbouring tiles
#Import "<std>" #Import "<mojo>" ' Bitwise ' ' 1 ' +++++ ' 8 +++++ 2 ' +++++ ' 4 ' ' blocks of + is our tile. The numbers around it you add up to get the tile ' to draw on that + position. ' ' If a tile is above and right we get the number 1+2 ' If a tile is left and below and right we get the number 8+4+2 ' Using std.. Using mojo.. Global mapwidth:Int=20 Global mapheight:Int=15 Class MyWindow Extends Window Field map:Int[,] Field tilemap:Int[,] Field tilewidth:Int,tileheight:Int Method New() map = New Int[mapwidth,mapheight] tilemap = New Int[mapwidth,mapheight] tilewidth = Width/mapwidth tileheight = Height/mapheight map[5,5] = 1 'all surrounded map[4,5] = 1 map[5,6] = 1 map[6,5] = 1 map[5,4] = 1 map[15,6] = 1 'right and below map[16,6] = 1 map[15,7] = 1 map[5,10] = 1 'left bottom and top map[4,10] = 1 map[5,11] = 1 map[5,9] = 1 createtilemap() End method Method OnRender( canvas:Canvas ) Override App.RequestRender() ' Activate this method canvas.Clear(Color.Grey) drawmap(canvas) ' if key escape then quit If Keyboard.KeyReleased(Key.Escape) Then App.Terminate() End Method Method createtilemap() For Local y:Int=0 Until mapheight For Local x:Int=0 Until mapwidth If map[x,y] = 1 ' ' Here we calculate which tile should be drawn at the current position. ' This is done by reading above/right/bottom and left of the current position. ' If above is a tile then we increate the value with 1 and right+2 bottom+4 ' and left +8. Local bitwise:Int=0 If map[x,y-1] = 1 Then bitwise+=1 If map[x+1,y] = 1 Then bitwise+=2 If map[x,y+1] = 1 Then bitwise+=4 If map[x-1,y] = 1 Then bitwise+=8 tilemap[x,y] = bitwise+1 End If Next Next End Method Method drawmap(canvas:Canvas) For Local y:Int=0 Until mapheight For Local x:Int=0 Until mapwidth If tilemap[x,y]>0 Then drawtile(canvas,tilemap[x,y],xtilewidth,ytileheight) Next Next End Method Method drawtile(canvas:Canvas,num:Int,x:Int,y:Int) num-=1 canvas.Color = Color.Blue canvas.DrawRect(x,y,tilewidth,tileheight) canvas.Color = Color.White canvas.DrawRect(x+1,y+1,tilewidth-2,tileheight-2) canvas.Color = Color.White Select num Case 0 'naked block Case 1 'block above present canvas.DrawLine(x,y,x+tilewidth,y) Case 2 'block right present canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1) Case 3 'above and right present canvas.DrawLine(x,y,x+tilewidth,y) canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1) Case 4 'block below present canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1)'below Case 5 'above and below present canvas.DrawLine(x,y,x+tilewidth,y) canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1) Case 6 'right and below present canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1) canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1) Case 7 'top and right and below present canvas.DrawLine(x,y,x+tilewidth,y)'top canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1)'right canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1)'below Case 8 'block left present canvas.DrawLine(x,y,x,y+tileheight)'left Case 9 'left and above present canvas.DrawLine(x,y,x,y+tileheight)''left canvas.DrawLine(x,y,x+tilewidth,y)'above Case 10 'left and right present canvas.DrawLine(x,y,x,y+tileheight)'left canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1)'right Case 11 'left and right and above canvas.DrawLine(x,y,x,y+tileheight)'left canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1)'right canvas.DrawLine(x,y,x+tilewidth,y)'above Case 12 'left and below present canvas.DrawLine(x,y,x,y+tileheight)'left canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1)'below Case 13 'left and below and top canvas.DrawLine(x,y,x,y+tileheight)'left canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1)'below canvas.DrawLine(x,y,x+tilewidth,y)'top Case 14'left and below and right canvas.DrawLine(x,y,x,y+tileheight)'left canvas.DrawLine(x,y+tileheight-1,x+tilewidth,y+tileheight-1)'below canvas.DrawLine(x+tilewidth-1,y,x+tilewidth-1,y+tileheight-1)'right Case 15'all surrounded canvas.DrawRect(x,y,tilewidth,tileheight) End Select End Method End Class Function Main() New AppInstance New MyWindow App.Run() End Function --v
Latest Update When you have a tile map you might have tiles that fit next to each other. For instance a single wall block would have edges on all sides while if there is another wall next to it then the side where it connects would look different. When you go through every possible connection that a tile can make above/left/right there is 16 different tiles. The Bitwise technique lets you automatically find that tile. The example code show how to do this : ( I learned this from a book called "Procedural Content Generation for C++ Game Development" which was given away for free at packt a while ago.)

Comments
Wednesday, 23 January 2019, 09:03
Jayenkai	I typically use a function labelled Mat(x,y) which fills a matrix array of 9 values. Each game tends to have a specifically coded mat function, but in general they end up specifying where walls or floors or other objects are, in relation to the given x,y. The numbers 1-9 are layed out the same as the numbers on the Numpad, for ease of "glance at the keyboard to remember which is which", with 1 being bottom left, 9 top right, 5 middle, etc.. But, yeah, the same idea. Fill the matrix for the player, or enemies, or falling objects, etc. Even though the code inside the function can be drastically different between games, the way they're used is usually the same, and it's good to use common techniques between games. .. in many ways, I'm the reverse of "reusable code" in that my game code stays the same, and all the function code is different!!!
Wednesday, 23 January 2019, 09:51
spinal	I did a similar thing in a version of sensitive to calculate the tile used for the shadows. Don't know if it was any faster, but it sure felt more 'proper'.
Wednesday, 23 January 2019, 11:32
rockford	I've done something similar for a number of my older games, including B'lox!, Drench and a Puyo Puyo clone (to name just three).

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