Hello, When I try to implement a WM_SIZE handler to keep my geometry from getting deformed, my edges get really jagged when I enlarge my window. Currently, I reset the device. Then I set my new window dimensions, calculate the new aspect ratio and then create and set the projection matrix. Am I missing something? Thanks.

I think you have to recreate all the resources on the video card (vertex buffers, textures, etc.) as well, though that should not affect it that way... Are you sure you are setting the new Presentation parameters structure to the correct winbdow size? If you set it too small, DX will strech the image to fit the window. Make sure to use the client size for the window.

Ah, I wasn't rebuilding my presentation parameters. Thanks