How to make map editor with XNA?

Question

I have a problem with making map editor in XNA. I'm making a 2D tile based map editor.

The problem is, I need every tile I put in map editor to be X: 0, or X: 32, or X:64 and so on, not 1.10, 2.99, 5.62, etc. You see, it has to be exactly i*32 tiles, where i is whatever number, not decimal. Thank you if you help.

Answer 1

The easiest way to "snap" coordinates to a grid is this:

    int objX = (int) Math.Floor(mouseX/tileWidth)*tileWidth;
    int objY = (int) Math.Floor(mouseY/tileHeight)*tileHeight;

Answer 2

Great OpenSource XNA map editor. http://gleed2d.codeplex.com/

You can fully customize the ground grid and enable grid snapping to make maps. Also since it's opensource you can edit it to suit your exact needs.

I've used it myself.

Answer 3

I like the solution here, but I'm currently using

                            // for example 100 - (100 % 32 (which is 4)) = 94 
Vector2 placementPosition = mousePosition 
               - new Vector2(mousePosition.X % 32, mousePosition.Y % 32);

which works perfectly, too