As I mentioned in my previous post, I was getting some strange vertical lines appearing in my deferred lighting result. After I turned down the ambient light to make the lighting a bit more realistic, the lines became even more pronounced.
Casting that problem aside for a bit, I decided to increase the resolution because 800x600 just wasn't cutting it anymore. I went with a widescreen resolution because both my laptop and my desktop have widescreen screens. I settled on 1280x720 because 1920x1200 would just be overkill right now, in my mind.
The problem with increasing the resolution was that the lines got even worse! Now I was getting horizontal lines as well as vertical lines, so it looked like a big checkerboard mess. I spent several days trying to figure out what was going wrong. At first I thought it was a bad driver/GPU in my laptop. So, I went to test it on my desktop, but I found out that my power supply was dead. Luckily my brother let me remote into his PC and run the app. I got the exact same results, so I knew it wasn't my GPU. I then installed FX Composer to have a better debugging IDE. I soon discovered that I was using wrong texel offsets to sample neighbors in the world position texture. This removed the lines from FX Composer, but they were still appearing in XNA. I was messing around with my sampler filters when I finally fixed the problem by switching them from Point to Linear. While it does get rid of the lines, it comes at a cost. I am now getting about 18fps average. Obviously the change in resolution also figures into that as well.
I have some interesting new screenshots to share.