## Sunday, October 16, 2011

### DDTe3 Hour 18 - Hex Sliding Puzzle

I have decided to switch back to posting my entries here on Sunday evenings. I was actually thinking of dropping this blog and just posting to Google+, but figured that this has a bit more permanence then G+ posts do. This article continues my series on Dozen Days of Tiles episode 3, where I created 8 games in 24 hours. This entry covers the creation of my hex sliding puzzle.

Originally, I was not thinking about doing a hex-based sliding puzzle as realistically you can not slide hexes as they form a really nicely locked pattern. Puzzle games do not necessarily have to reflect reality, so after thinking about it for a while, I figured that this would be an interesting game to develop. After playing the finished version of the game, I am quite glad that I did as it is actually a really fun variation of the sliding puzzle.

The hard part to creating this game is in dealing with the sliding. A hex grid can be thought of as a three-axis system, but that is only partially true. While the Z axis does exist, it is dependent on the X axis and  the Y axis. This means that manipulating the Z axis means that you are actually changing the X and Y axis. This got me thinking that if I just move along both the X and Y axis at the same time, things should work. Here is the new version of the sliding code.

PuzzleGallery.HexSlidingPuzzleGame.prototype.moveSlider = function(p)
{
var tempX,tempY;
var hp = new PuzzleGallery.HexPoint();
hp.setPointFromGrid(p.x, p.y);

while ((this.slider.x != hp.x) || (this.slider.y != hp.y)) {
tempX = this.slider.getGridX();
tempY = this.slider.getGridY();
if (this.slider.x > hp.x) {
this.slider.translateX(-1);
} else if (this.slider.x < hp.x) {
this.slider.translateX(1);
}
if (this.slider.y > hp.y) {
this.slider.translateY(-1);
} else if (this.slider.y < hp.y) {
this.slider.translateY(1);
}

this.puzzle.swapPuzzlePieces(tempX, tempY, this.slider.getGridX(), this.slider.getGridY());
};

this.view.update();
}

When trying to see if this method works, sliding along the proper axis works fine but if a shift is not axis-aligned, the results were a bit strange. The quick solution to this problem is to simply limit sliding to axis-aligned slides, which is what the game is going to do anyways. I do not like stop-gap solutions but prefer when possible to know why things are not working.  This problem actually was simple enough to figure out, as the strange results come from moves that are positive or negative along both the X and Y axis. Movement along the proper Z axis always results in opposite mathematical operations being applied to X and Y.

While I could probably special case the sliding of positive or negative X/Y combos, I really wanted to get this game finished in under an hour so I would have more time for the next game as it is a fairly complex game. As I would not be able to rely on sliding to random points as I did with the original sliding puzzle, my quick and dirty solution was to simply increase the amount of random slides five-fold calling the sliding through the axis-checking onTileClicked method.

The next (and as it turned out final) game in this series is still not the rotation puzzle but something never released on the Blazing Games site. The development on that game will start being covered next week.