Okay, I've been programming for a long time, but this is my first serious attempt at real 3D graphics programming in awhile so bear with me. I'm working on a 3D realtime strategy game in DirectX 8. I've got a basic framework for game logic working, but I'm having some trouble with clicking. Usually, in an RTS, you click on the battlefield where you want a unit to move. In 2D there's no problem with this, but in 3D, you have projection to deal with. For example, if you're zoomed out really far, where you click in screen coordinates is going to be a lot less than where you want the player to move in world coordinates. So, how do I convert from screen coordinates to world coordinates? I tried using D3DXVec3Unproject but it gives me divide by zero when I put in the world matrix and odd numbers when I put in the "battlefield" matrix. Can anybody shed some light on my problem? I hope I'm explaining it well enough.
Here is a little image I made to illustrate what I'm talking about. The red square is the viewport and the blue square is the "battlefield." The black X is where the user clicked on the screen and the blue X is what that would translate to in world coordinates. I want to know what the world coordinates are under the black X (off the battlefield, in this example).
Here is a little image I made to illustrate what I'm talking about. The red square is the viewport and the blue square is the "battlefield." The black X is where the user clicked on the screen and the blue X is what that would translate to in world coordinates. I want to know what the world coordinates are under the black X (off the battlefield, in this example).