Well, results are not too good for TFTD.
Since there are 4 different palettes (terrain, shallow, medium and deep), the "semi-shade" sprites are quite different with different palettes. Sprite with full light is the same, but "shading curves" are too different.
Current algorithm for xcom1 which resembles vanilla by 99%:
- Full light sprite.
- Medium shaded sprite (the 6th grade of shade).
- For shade values 0-6 it takes interpolated result between full light and medium shaded sprites.
- For shade values >6 it takes medium shaded sprite and applying linear shading curve with black clamp (decreasing each of RGB values by some number with each step, red is decreased slowly, so shades are slightly reddish, which is xcom1 visual style).
For TFTD sprites medium shaded sprites are different for each depth. Shading curves also slightly differ (terrain is neutral, and different depths has different slopes with different blue component decreasing speed).
For vanilla 8bit sprites we can generate "medium shaded" versions on battlescape load, and use different shading curves, and result might be not that bad.
But for custom sprites, drawn in 32bits, the artist would need to draw 5 different sprites. Full light, and 4 semi-shaded version for each depth. It's not really nice thing, but currently I can't think of other way, besides giving no fucks on vanilla tftd look and feel and implementing something entierly different.
