One of the final pieces of the puzzle regarding Dreamcast mipmapping was finally solved! Dreamcast had a feature called “Mipmap D-Adjust” which in practice is nearly identical to mipmap LOD bias, with the only difference being that it works with a factor (* d-adjust) instead of a bias (+ lod bias).
Flyinghead came up with the implementation, it has been merged and should be in the nightlies later today.
We made two comparisons here – one with Daytona USA 2001, the other with V-Rally 2 –
Daytona USA 2001
Please check the link down below so you can see the difference –
http://www.framecompare.com/image-compare/screenshotcomparison/JCBBCNNU
The tree on the left is more detailed now in the far distance, same for the public next to it.
V-Rally 2
Here the difference is even more pronounced – please check the link down below so you can see the difference –
http://www.framecompare.com/image-compare/screenshotcomparison/DZLDLNNX
The road looks a bit blocky and low-detailed with mipmap D-Adjust off, while it looks normally with it turned on.
