After browsing the web and reading dozens of examples and tutorials I still can't figure out how to translate mouse X;Y screen position in pixels to X;Y isometric tile index. All the examples I tried returned strange values.

The attached picture shows exactly the tiles' redering order. The Zig-Zag rendering mode was so simple to implement with the help of a colored coded tile. But this diamond shapped design is really giving me a hard time.

I guess the formula involves the following variables:

- MousePos.X

- MousePos.Y

- TileWidth

- TileHeight

- ScreenWidth

- ScreenHeight

Now I just need to know how to put the pieaces the together as I really can't see any logic behind it.

Thank you very much for any possible help.

Thanks for the reply.

I already knew those links. The first one doesn't explain how having the mouse at the middle-top of the screen translates itself to 0,0 isometric coordinates. wtihout knowing this the colored tile is useless. As for the second link, I'm affraid that math is too advanced o me...

its simple really, I'll start from tile--> screen and then see how it goes from screen to tile. Of course you should replace the numbers 64 and 32 by constants for easy change.


tile --> screen
for every tile you go in the X direction you go 64 pixels right and 32 pixels down,
for every tile you go in the Y direction you go 64 pixels left and 32 pixels down,

on screen right=positive x, left=negative x, up=negative y, down = positive y

so we get:
pixel_x = X_LOCATION_OF_TOP_MIDDLE_TILE + 64*tile_x - 64*tile_y
pixel_y = Y_LOCATION_OF_TOP_MIDDLE_TILE + 32*tile_x + 32*tile_y


now to do the screen --> tile
for ease of writing, pixel_x = px, tile_x = tx, X_LOCA... = X0

equation1: px = X0 + 64*(tx-ty)
equation2: py = Y0 + 32*(tx+ty)
we want to find equations for tx and ty when given px and py, so we do some algebra:

eq1+2*eq2 = px+2py = X0+2Y0 + 128*tx
---> tx = (px+2*py -X0-2Y0)/128

eq1-2eq2 = px-2py = X0-2*Y0 -128ty
---> ty = (px-2py - X0+2*Y0) /(-128)

I hope that was clear, and maybe you learned some math from it


the matrices are just compressed way to do the algebra.

[Edited by - Iftah on December 5, 2008 6:08:28 AM]

Thank you guys for the precious info!