Isometric tile selection

Question

I'm not all that good with Maths. I'm trying to make a function to convert mouse coordinates into a particular tile in an isometric view.

All of the algorithms I have seen so far work with the X & Y axes going diagonal, my game is currently set up like this, and I would like to keep it so.

Is there an algorithm so that if the mouse was at the red dot, it would return the coordinates of the tile that it is sitting on? (6,2)

Answer 1

Well, I'm assuming that for a given tile, you know the real-axes coordinates for each of its corners. i.e for the given tile (1,0) in your picture, you know its left-most corner is at, let's say, (5,10) on the actual xy axes. If so, you can use Java's Polygon class: create a Polygon instance containing a given tile's xy coordinates for each of its corners, then use the contains(x,y) method giving it as arguments the position of the mouse cursor, and it will tell you if mouse of tile or not:

int[] tileXcoords = new int[tileLeftMostCornerX, tileLowerCornerX, tileRightMostCornerX,tileUpperCornerX];
int[] tileYcoords = //... similar for the y coors (keep the order of the corners the same as for the x array)

Polygon tile = new Polygon(tileXcoords, tileYcoords, 4);
if(tile.contains(mouseX, mouseY)) {
    //mouse is over tile
}