[owenisas]

Adds support for STEINS;GATE 0 (Steam) as a new sg0 profile, plus a few engine fixes it needed. Opened as a draft: it is large, and I am happy to split it (for example the Bink 2 port on its own) if that is easier to review.

Commits

1. Build the Bink 2 decoder into the FFmpeg overlay port. SG0 Steam ships its movies as Bink 2. The overlay port builds FFmpeg 7.1.2 with the binkvideo2 decoder from SharpEmu's FFmpeg fork (sharpemu/ffmpeg-core@3b502d4, LGPL-2.1-or-later). It also normalises the alpha flag to a boolean: the raw value (0x100000) made the decoder walk past the fourth plane and crash on alpha movies.
2. Serialize DDS texture loads. The DDS decoder keeps file-global state while spritesheets load concurrently, so loads could interleave.
3. Allow backlog entries without glyphs. AddMessage used Glyphs.back() on the previous entry. SG0 adds empty lines through SetRevMes, which crashed intermittently.
4. Play full-range and alpha Bink 2 frames. Bink 2 decodes to full-range YUV, and to YUVA420P for alpha movies. The video shader expects limited range, and alpha in the bottom half of the frame. As a result, movies showed crushed blacks and clipped whites, and alpha overlays did not show at all. Frames are now repacked on upload; there are no shader changes.
5. Add STEINS;GATE 0 (Steam) support.
   • Instruction set: an SG0 instruction set, CC's table corrected against SG0's scripts. All 178 scripts decode without desyncs; operand layouts agree with sc3ntist.
   • Profile:
     • mounts, movie order, the font atlas with per-glyph metrics, and the charset;
     • the save layout, with the script message table and CG album;
     • TIPS and key bindings, the bindings taken from the game's own help page.
   • Phone (PhoneSG0): the triggers that select the routes, and RINE threads with replies.
   • Screens:
     • save, load and quick load;
     • system message boxes;
     • the system menu, backlog, TIPS, config, help and title menu;
     • the EXTRA library (CG viewer, sound player, movies) and the clear list.
   • Engine changes, all scoped to SG0:
     • SG0 rendering paths and cut-ins (SetCutin);
     • movies on priorities above the scene layers;
     • the looping title movie;
     • the title menu ignoring input while another screen is focused.

Testing

On macOS arm64 with the Steam version:

• Routes: all six endings were reached by force-skip playthroughs with the phone decisions that select them: Promised Rinascimento, Twin Automata, Recursive Mother Goose, Gehenna's Stigma, Vega and Altair, and Milky-way Crossing on a second playthrough.
• No hangs or crashes after the backlog fix.
• Movies: frames match the source decode in colour range, and the alpha overlays (IMV005-007) show.
• CGs: they match the source images.
• Not covered: other platforms or renderers; audio was not compared by ear.

Known gaps

• No name box, and no AUTO/SKIP icons.
• The PC build ships no system sound effects, so menus are silent; the original most likely is too.
• IMV006's first frame uses a frame flag the decoder does not handle, so each loop starts one frame late.

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[Gunoshozo]

Nobody gonna read that vibe slop buddy

[owenisas]

Fair enough, that was way too much to review in one go. I've split it up: #565 to #568 are small standalone fixes, and #569 is the first STEINS;GATE 0 step (startup through the title into the story text). I'll open the rest one at a time after that's in. Thanks for the heads-up.

[Emberind]

You misunderstand. We don't accept vibe-coded PRs

[owenisas]

You misunderstand. We don't accept vibe-coded PRs

Ok, got it. Although it's tested and played, but the agent probably didn't consider human maintainablilty and edge cases. Thanks for letting me know though.