There is now a skydome in the background, which uses a lookup texture to get the colors based on the time of day and altitude of the sky. The objects become bright and dark based on the time of day using a sine function, which I added various coefficients in order to get the transitions looking how I want them to. The objects also are also light differently with ambient colors based on the sky and light angle.
There are a few adjustments still to be made with the sky colors. I'm considering using another lookup texture to get the brightness of the objects which would replace the sine function operations, and much easier to adjust.
I've also been working on some code cleanup and re-organization. Chunks are now handled as a group with a ChunkManager class, which makes the code in the game state much easier to read through. Some tweaked camera physics and controls, as well as voxel shader code.