Feature request: render aspect ratio override (wider viewport / FOV)

[keepitahundred]

Hi,

Requesting support for overriding the game’s render aspect ratio so the 3D scene is drawn with a wider viewport instead of a fixed 16:9 frame.

System

• MacBook Pro 16" (M1 Max)
• macOS 26.x
• Display: 16:10 (tested at 1728×1117 and 2056×1329)
• Title IDs:
  • Astral Chain 01007300020FA000
  • Super Smash Bros. Ultimate 01006A800016E000

Current behavior

• DM_FULLSCREEN=1 is correctly applied from env.txt (log confirms it, launcher can be skipped).
• In front_mac.m the present path deliberately fits the game’s picture to the drawable with black bars to keep the game’s aspect ratio.
• DM_RENDER_SCALE only scales the existing render targets (documented as render_base); it does not change the aspect ratio.
• Simple stretch of the final present texture is undesirable (distortion).

Request

Ability to change the aspect ratio used by the game’s render targets / viewport so more of the world is drawn.

Possible approaches (easiest first)

1. Present-path option — add a switch that skips the letterboxing in the present path (even if it results in a stretch). Lowest effort, host-side only.
2. Extend the existing render-scale stub — the same mechanism used for DM_RENDER_SCALE could also adjust the aspect ratio of the main color/depth targets (or the viewport passed to the game), controlled by something like DM_RENDER_ASPECT=1.6 or DM_ASPECT_RATIO=16:10.
3. Projection / FOV hook — if a game already has a known camera setup point, adjust the aspect component there (more title-specific).
4. Optional community patch loading — allow loading of pre-made exefs/romfs aspect-ratio patches if they only touch view/projection constants.

A single environment variable that works with approach 2 would already solve the problem for most games and users.

This would let the Metal host render a true wider FOV on non-16:9 displays instead of letterboxing or stretching the final frame.

Happy to test any experimental builds or patches.

Thanks!

What you propose

Override the game’s render aspect ratio so the 3D scene is drawn with a wider viewport instead of a fixed 16:9 frame.

How it could work

1. Present-path option (lowest effort)

   • In front_mac.m, the present path currently fits the game’s picture to the drawable with black bars to preserve aspect ratio.
   • Add an environment variable (e.g. DM_PRESENT_STRETCH=1) that skips the letterboxing and simply scales the final texture to the full drawable size.
   • Touches only the Mac front end present path. No game changes required.

2. Extend the existing render-scale stub (best balance)

   • Games that already support DM_RENDER_SCALE have a stub on the function that decides the main view / render-target size (render_base in the game notes).
   • The same stub could accept an additional aspect override (e.g. DM_RENDER_ASPECT=1.6 or DM_ASPECT_RATIO=16:10) and adjust only the width of the color/depth targets before they are created.
   • Touches the existing rewriter stubs (patches.py / per-game patches) and the host’s render-target creation path in nvn_mtl.m.
   • HUD can remain 16:9-centered as a first step.

3. Projection / FOV hook (higher effort)

   • Locate the game’s camera projection setup and adjust the aspect component of the projection matrix.
   • More title-specific; would live in the same per-game patches.py style as the current frame-rate and render-scale stubs.

Any of these would be controlled by a single environment variable so users can enable it from env.txt without rebuilding.

Platforms

Mac

[Smatjoy]

Another data point for the present-path option (approach 1): Metroid Prime Remastered 1.0.0 (010012101468C000) on a MacBook (Apple Silicon), 3440x1440 ultrawide monitor.

The community exefs patches (theboy181, "2K -1080p" + "21:9 v4") converted to Atmosphère cheats load fine through the cheat engine: cheats: build 67C9CA1428222752: 3 cheats (0 master, 3 on, 0 broken, 3 runnable), and the build ID matches. The 2K patch raises the swap chain to 2560x1440 (WindowInitialize swap chain 2 textures ... first 2560x1440). The 21:9 patch changes the aspect constants/projection so the game draws a 21:9 view, but it still writes it into a 16:9 buffer, because patches can't change the swap chain's aspect.

The window drawable is 3440x1440, and present_viewport (dm/gfx/nvn/nvn_mtl.m) keeps the buffer's aspect and pillarboxes unless the two ratios differ by under 1 %. So the pre-widened 21:9 image shows as a 16:9 box with black bars, which defeats the patch. For games where the community already ships an aspect patch like this, a switch that skips the letterboxing (e.g. DM_PRESENT_STRETCH=1) would be enough to display it full width.

Update: a workaround works without touching the host. Instead of stretching the 16:9 buffer, I changed the widths in the 2K cheat so the game renders natively at 21:9 (cheat text only): docked 2560 -> 3440 (height stays 1440), handheld 1920 -> 2584, and the four 1600-wide constants -> 2152 (all multiples of 8). Combined with the 21:9 patch, the swap chain is 3440x1440, the window drawable is the same size, so present_viewport takes its "ratios differ by under 1 %" branch and fills the whole canvas: no black bars, no stretching.

Result on an M5 MacBook, LG ultrawide, 3440x1440, Metal 4: a steady 60 fps (GPU 15.2 ms, frame interval 16.67 ms), HUD and 3D view correct in the first stage. Screenshot below. As the patch notes say, videos and some menus are stretched. This doesn't generalize: it needs a per-game aspect patch whose render size can be changed by cheat, so a present-path option (approach 1) would still help games that don't have one.