Sky Deck downgrades

Like other Sonic games, every level in Sonic Adventure was designed around a certain theme. There was also some feature or special effect that was specific to a particular level. For Emerald Coast that was the ocean waves effect (removed in SADX), for Windy Valley it was the tornado etc. Sky Deck, a sky-themed level, also has a unique gimmick: every once in a while the Egg Carrier changes altitude, and the environment descends into darkness. The wind also gets stronger, sometimes blowing things away. Like every other level in Sonic Adventure, it was made to be visually impressive. The SADX version of the level has some of the most severe downgrades in comparison with the original Dreamcast version. A plethora of special effects is missing, and the sky, which was the highlight of the original level, is mostly static. Let’s have a look at some of the most visible problems with this level.

In Sonic’s Act 1, you may notice that UVs on some models were stretched, but the textures remained the same resolution. This degrades the visuals slightly and makes the bottom of the cannon appear misaligned. Also note the near-complete absence of lighting in SADX screenshots:

The cloud layers in Sky Deck are completely static in SADX. Although making the layers scroll can be achieved with a simple hack, the sky is not moving in the ports. The lack of cloud movement makes the level feel empty and unfinished.


The first act has several areas where platforms are broken into pieces that fly off the screen. Broken platform debris are misrotated in SADX. While not a major issue, it makes the destroyed platforms look strange. Here’s what it looks like right after the cannon hits the platform:

As you progress through the level, you’ll notice that the sky gets darker when the Egg Carrier descends into the clouds. In the Dreamcast version the entire environment, including characters and objects, reacted to this by switching to a different lighting palette. In SADX, most of the environment ignores lighting changes. The PC version also adds fog that is too thick for this area and has a color that doesn’t fit too well because it makes things brighter when they are supposed to be darker:

Areas like these look a lot worse without proper lighting:

On the Dreamcast, the transition between “normal” and “dark” versions of the sky was smoother: before the sky changed texture, it faded out to white with an additive effect, and then faded back in with the new texture. Fog also became brighter and thicker during the transition, then it went back to “normal” mode, which also had a “dark” and a “light” version. All of the above details are lost in SADX. The sky texture changes abruptly, there is no fog adjustment, and the additive blending of the sky is missing.


In the original game you can hear Eggman’s announcements “Descending into the clouds, slow the ship down!” and “Go up – full speed ahead!” whenever the ship changed altitude in the first section of Act 2. These announcements are never heard in SADX because they were removed from the level’s soundbanks, even though the game still has the code to play them*. We can only speculate why, but my guess is they were removed after the SADX sound system was retooled to use fewer soundbanks. The Dreamcast version had Japanese and English soundbanks for some levels, while SADX only has Japanese/English versions of character voice soundbanks.

*The code to play the announcements is buggy and the announcements get cut off before they finish playing. This also happens in the Dreamcast version, but the problem got worse in SADX because the code was not adjusted for 60 FPS. The Sound Overhaul mod fixes both problems, and the announcements play properly at any framerate.

All three acts of Sky Deck have some questionable texture changes. Some of the new textures look passable, others look less detailed and more washed out. The PC version suffers the most from this because the textures were mirrored and recompressed (twice):

Act 3 has also had some retexturing work done in SADX. Some of the textures are recycled: for example, in the screenshots below the level piece uses a texture that is also used for the elevator in both versions of the game. There are also some yellow vertex colors placed sparsely around various level pieces, which arguably don’t fit the level’s theme:

The crane in the screenshots below survived the Gamecube transition, but got slightly broken in the PC version due to a texture mirroring issue. While in this particular instance there is no major issue, it’s worth pointing out what the crane is supposed to look like:

Some objects have lost their effects in the ports. For example, the cannon you fight at the end of Act 1 has simpler texturing and lacks its shiny metal surface in SADX. A similar change happened to the cannon at the end of Act 2:

The sky in Act 3 also looks different because all of its effects were removed in the ports. The Dreamcast version has a sky with moving clouds, which looks quite impressive in the scene where Sonic descends to the lower segment of the level. The Gamecube version doesn’t have moving clouds and you can only see the background. Both Gamecube and PC versions have skybox scale and draw distance issues that make the sky look broken. You can also see the metal struts have lost their transparency in SADX:

Here’s a video of this effect in motion. Notice how unnatural and broken the sky looks on the Gamecube. The visible cutoff is caused by reduced skybox draw distance in the ports.


The glass walls inside cargo holds in Act 3 are supposed to be transparent, but the Dreamcast version is the only one that renders them correctly. SADX makes them opaque, which looks strange:

Minor but funny issue: the code for rendering the robot maid cleaning the floor behind the blue glass is broken and disables the glowing piece under her skirt (left – normal, right – disabled). It disappears only in one of her animations, and shows up if you pause the game. This happens because the variables in the function are in the wrong order.

An overview of Knuckles’ level shows the broken skybox again and a strange looking green fog that doesn’t fit the theme of the level too well. This is also likely the only area in the game where the PC version’s unnecessary processing of material colors fixes a problem – the bottom of the lever is no longer white:

Sky Deck doesn’t have too many downgrades from SA1 in terms of quantity, but quality-wise those downgrades are certainly some of the worst in the entire game – with lack of lighting, missing cloud movement and a broken skybox in Act 3. This level can be fixed with Dreamcast Conversion, where I restored cloud movement and implemented various effects, such as additive blending for skybox transitions. The Lantern Engine mod restores the vibrant palette lighting, and the Sound Overhaul mod adds back missing announcements in Act 2. To learn more how to install the mods, head over to the “Fixing the PC version of SADX” section.