Mystic Ruins Past is a relatively small location, but even a small level like this has had some issues, ranging from minor problems to complete removal of things that define the level’s theme.
From a quick look, other than a strange looking skybox in the PC version, there are no major changes seen in the Echidna City. SADX fixes lighting on the trees that ignore it in the Dreamcast version and adds vertex colors around some areas, which can be counted as an improvement:
Not a downgrade, but the well is now shut to prevent you from seeing the Dreamcast water texture. The texture on the columns was flipped for some reason – a rather nonsensical change because the texture itself wasn’t changed:
The Emerald Altar area has more noticeable differences. SADX adds prominent fog and the lighting is brighter and more washed out:
The most noticeable difference in this area is the sea textures. Like other Adventure Fields, the Past also uses additive blending for the water, which consists of two texture layers (and another layer for the distortion effect on the Gamecube). From a technical standpoint it can be considered superior to the original opaque water texture, but color selection is a bit strange as it doesn’t fit the stage’s theme very well. Another problem is that the SADX water is too dark and too transparent, which makes the bottom of the skybox visible through it. The sea also ignores lighting and is affected by fog in the PC version, which makes makes it look worse when the Emerald Altar is on fire:
In the Dreamcast version the water around the altar reflects some objects like palm trees and columns. This effect is created by making the floor transparent and placing “reflected” models underneath it. These reflections are still present in the SADX level, but they fail to render properly due to the game’s transparency problems. In addition, the water texture was made so transparent you can barely tell there is water. The reflections were especially effective at creating the atmosphere in cutscenes featuring the Emerald Altar on fire, which are less impressive in SADX.
Perhaps the most noticeable SADX downgrade in this level is the fire effect. In the Dreamcast version the lighting transitioned between darker and brighter shades of red by alternating between two palettes – more on that in the Lighting section. The effect is removed in SADX. The transitions also affected some objects, such as trees, which now have simpler lighting. The PC version adds thicker fog that doesn’t help the scene.
Loss of lighting detail is also visible in the Master Emerald area, where distant scenery is no longer tinted red, the Master Emerald is fullbright and the glow of the emeralds blends with the background:
Character lighting in this level was also downgraded quite badly. The Gamecube version in particular lacks detail besides basic coloration most of the time. You can still see some slight coloration depending on the camera angle, which suggests that a different light direction might’ve helped.
In conclusion, the Past has suffered from less downgrades than other areas in SADX, but loss of reflections and the unique two-palette fire effect make it a lot less impressive than the original level. While it doesn’t look too terrible overall, the Emerald Altar area cannot be called an improvement over the Dreamcast version. To revert to the original version of the level on PC, use the Dreamcast Conversion mod (which restores reflections), and the Lantern Engine mod that restores the fire blending effect. Read more about mods for the PC version here.