AGS: Whispers of a Machine - Invisible character not rendering correctly

[Thunderforge]

In Whispers of a Machine (ags:whispersofamachine), while listening to Tape #6 in Stina's apartment, Stina walks in while invisible. In the original interpreter, there is a slight distortion showing where she is, but otherwise she matches the background. In ScummVM, she retains the appearance of the hallway where she spawns.

Reproduction Steps

1. Load the appropriate save game from the attached zip file (Whispers of a Machine has "ironman" autosaves, and they are updated at the same time, so I'm not sure which files are actually needed)
2. Click on "Cassette Tapes" (numbers 5 and 6) on the center table to pick them up
3. Place "Tape 6 (Stina's Apartment)" in the tape player located below the portrait

After the first and second lines, the door will open slightly and creak and Stina (who is invisible) walks in, stopping near the window. After the tape is completed, Vera comments on it, then Stina drops her invisibility and tries shooting Vera.

Original behavior

Stina matches the background of where she is standing and is only visible through a slight distortion on the edges of her silhouette. Thus the player can only see her by looking closely, and it may be subtle enough that the player misses her entirely. This can be seen in ​this Let's Play.

ScummVM behavior

Stina always looks like the hallway, which contrasts with the rest of the background when she walks into the room. This makes it blatantly obvious that she is standing there. See attached animated GIF.

Possible other issue

I think I recall this happening also in ​this scene near the end of Day 3 where Stina is invisible near the bushes. My recollection is that Stina remained looking like leaves until she reveals herself, rather than matching the background as in the original interpreter. Unfortunately because of the ironman saves, I don't have a save game to double-check.

Tested on

• ​Steam version of the game, macOS
• ScummVM 2026.1.0, macOS

[Max833]

I've tested this with the orignal AGS engine 3.6.3 with software renderer and there are no issues. So this is very likely an ScummVM-only issue. Could be related to: https://bugs.scummvm.org/ticket/13187