What's Down There?

I'm getting closer.  I formed a method that involved drawing small squares of different shades over and over, reducing my game's frame rate to 13 frames per second. Scrapped that idea.

Now I have figured out how to manipulate the pixels of a texture, so I am drawing a small texture, scaling it to cover the screen, then blending it with the image of my world. A lot faster, keeping a smooth 60 fps, but there are some alignment issues.  And my code is messy as hell.  I need to re-code my light-mapper, then tackle the issue of misalignment.  From there, I should be able to manipulate the pixels in an efficient manner and start the core shading code.