# Isometric tiles drawing and picking - JAVA

I'm trying to draw isometric tiles in Java and implement a tile picking system using the mouse cursor. I draw the tiles using math formulas I found and adapted to my tile textures which you can find below. Tiles are 64x64px but flat tiles are only 32px height even if I draw them using the 64x64 sprite.

public int[] toIso(int x, int y){

int i = (x - y) * tileWidthHalf;
int j = (x + y) * tileHeightQuarter;

i+=xOffset;
j+=yOffset;

return new int[]{i,j};
}

public int[] toGrid(int x, int y){

x-=xOffset;
y-=yOffset;

int i = (x/tileWidthHalf + y/tileHeightQuarter)/2;
int j = (y/tileHeightQuarter - x/tileWidthHalf)/2;

return new int[]{i,j};
}


The map is a simple 2d array where my tiles are represented by their id.

Here is a video showing what is actually happening: youtu.be/baCVIfJz2Wo

• Does this help? gamedev.stackexchange.com/questions/14274/… Sep 14 '17 at 15:45
• It seems not to work in my case. Thanks though. Sep 14 '17 at 16:03
• I don't fully understand what the problem is. Could you improve the question to highlight what you get and what you expect instead? Sep 15 '17 at 10:33
• Well, I'm trying to detect which tile is under my mouse when hovering the grid and render it with a different texture for the moment. The problem is, the tile selection isn't accurate at all, as you can see in the video I provided. Sep 15 '17 at 11:07
• The toGrid and toIso functions are clearly not reversible. If they are both accurate, you should be able to call toIso on a set of coordinates; and then call toGrid on that result and end up with essentially the same coordinates you started with (working with integers may mean you are off by a pixel or so however). Write yourself a quick unit test which dumps the coordinates into the console and see what results you get. If they vary wildly, then your calculations are likely wrong. Sep 15 '17 at 17:07

just wanted to say that I finally solved it. It was just a conversion to int issue. These are the final methods that I use. Hope it will help people who were trying to work with isometric tiles. Thank you !

public static int[] toIso(int x, int y){

int i = (x - y) * TILE_WIDTH_HALF;
int j = (x + y) * TILE_HEIGHT_QUARTER;

i += xOffset-TILE_WIDTH_HALF;
j+=yOffset;

return new int[]{i,j};
}

public static int[] toGrid(double i, double j){

i-=xOffset;
j-=yOffset;

double tx = Math.ceil(((i / TILE_WIDTH_HALF) + (j / TILE_HEIGHT_QUARTER))/2);
double ty = Math.ceil(((j / TILE_HEIGHT_QUARTER) - (i / TILE_WIDTH_HALF))/2);

int x = (int) Math.ceil(tx)-1;
int y = (int) Math.ceil(ty)-1;

return new int[]{x, y};
}