I did another iteration on this, while not everything is as it should, I think there was some improvement. This time I have captured a video. The transitions are better appreciated like this. Again let me know what you think.
The main issues with the previous iteration were the brightness of the sky (or lack of it), and how the distant features failed to blend with the sky. This time I made sure there was enough atmosphere so more light was trapped between the horizon and the eye. The distance to the sky is also consistent with the terrain dimensions, now the colors in terrain and sky match better.
A few comments in the previous post suggested a different method called "Precomputed Atmospheric Scattering". It certainly produces better results than the method I am using here, which is the one from O'Neil in GPU Gems 2.
I had a quick look at the method and saw that in its vanilla form it could run slower than what I have now. While the method uses precomputed tables as textures to accelerate rendering, all the work is done in the fragment shader. That means every pixel on screen now had to perform two or three additional texture fetches.
The method from O'Neil does all the heavy lifting in the vertex shader. Consider this scene:
The main issues with the previous iteration were the brightness of the sky (or lack of it), and how the distant features failed to blend with the sky. This time I made sure there was enough atmosphere so more light was trapped between the horizon and the eye. The distance to the sky is also consistent with the terrain dimensions, now the colors in terrain and sky match better.
A few comments in the previous post suggested a different method called "Precomputed Atmospheric Scattering". It certainly produces better results than the method I am using here, which is the one from O'Neil in GPU Gems 2.
I had a quick look at the method and saw that in its vanilla form it could run slower than what I have now. While the method uses precomputed tables as textures to accelerate rendering, all the work is done in the fragment shader. That means every pixel on screen now had to perform two or three additional texture fetches.
The method from O'Neil does all the heavy lifting in the vertex shader. Consider this scene:
The sky, even if it appears softly shaded, has only a few vertices:
I think in this case it makes a big difference.
The precomputed method could also run in the vertex shader, but then it would take some time to port the tables, which now are in pixel formats that cannot be read by the vertex shader.
Of course there is a chance I am reading this wrong. If you have worked in this area before and see what I am missing please let me know.
