I'm trying to implement a sweep selection for an RTS using OpenGL. I have one question about gluPickMatrix. On the OGL site, it says: PARAMETERS x, y Specify the center of a picking region in window coordinates. delX, delY Specify the width and height, respectively, of the picking region in window coordinates. If x and y is the center, does it select a region delX to the right, and delX to the left? Or is it delX wide, and x is located at delX/2. Jeff

After much time debugging and trial and error, I figured it out. The x and y coordinates are the middle of the matrix, and the matrix ix delX wide, and delY tall.

My problem was in selecting the y from the viewport. But its all good now.

Jeff