## Thursday, September 29, 2011

### DDTe3 Hour 15 - 16 Hex Puzzle Game

My series of posts on the creation of Dozen Days of Tiles episode 3 (Puzzle Gallery) continues with the creation of the hex puzzle game. This builds on the theory and code from the last couple of posts so please read those first.

With the HexTile class complete, the next step is to actually display the puzzle. The display of a hex grid is a bit more complicated then displaying a regular tile grid. If you draw a rectangle on a piece of hex graph paper, you will notice that you will be clipping half a hex on each end. This means that the width of a hex-tile is equivalent to the width of the display divided by the half a hex more than the number of desired tiles in the row. The height of a hex -tile is even more confusing to calculate. Because the rows of hexes overlap, the height of a row is essentially less than the height of a tile. When determining the tile height, it is best to think of each row (except the last) being ¾ of the height of a tile.

 figure 1 - Hex Clip

var halfWidth = Math.floor(clip.width / (puzzle.puzzleWidth * 2 + 1));
var quarterHeight = Math.floor(clip.height / (puzzle.puzzleHeight * 3 + 1));
this.tileWidth = halfWidth * 2;
this.tileHeight = quarterHeight * 4;

Laying out the tiles is pretty much the same as laying out a grid, except that every other row is offset by half a tile. Unlike the grid based games, the border is kind of important here as bits of the image are cut out by the irregular shape of the board. The border is drawn the same as it was in the original BasePuzzleView class except that the top and bottom extend a quarter of a tile into the board and the left and right borders extend half a tile into the board.

With the puzzle drawing properly, we now have the problem that the board is drawn in it’s solved state. Moving the hex tiles around is a bit trickier and I was about to write code to calculate the placement of a hex when I realized that I would be looping through them all anyway. By using the Puzzle value to determine which hex goes in which screen location, the update code was only marginally different from the original update code.

The final challenge, which I cheated on, is the click handling. Instead of properly determining which hex was clicked on, I assumed that most people are going to be clicking near the middle of a hex anyway so went with the much simpler bounding box. I may do proper checks later but for now the method is good enough.

With the click support added, creating the first puzzle was simply a matter of copying the original PicturePuzzle Class and changing BasePuzzleView to HexPuzzleView where necessary. With this done, the first hex based puzzle is done and it is time to start on the next one.