A Direct3D 9 to Metal translation layer for running Fallout: New Vegas on macOS via Wine. A Wine-side d3d9.dll captures D3D9 state and bulk uploads, a shared backend bridge serializes each frame into shared memory, and a native Metal viewer replays the frame on Apple GPUs.
As of July 2, 2026:
- In-game 3D rendering is correct. The long-standing geometry corruption was root-caused to the MSL emitter mishandling non-prefix destination write masks (
add r0.yzw, ...) — 22% of all instructions in FNV's shipped shaders were miscompiled. The emitter now builds full-width results and stores through mask selection. - The translated-shader path is validated against the game's own corpus: all 15,535 real shaders in
Data/Shaders/*.sdpparse and emit, and sampled Metal compilation passes (dx9mt/tests/corpus_emit_test.m). - D3D9 fixed-function alpha test and table fog are emulated inside every translated pixel shader via a per-draw params buffer (leaf cutouts, distance haze).
- The shader parser is self-checking: SM2+ operand-length fields are validated on every instruction, so an opcode-table mistake fails one shader cleanly instead of desyncing into compilable garbage.
- Draws upload only the geometry they reference (index-scan windowed uploads), keeping every IPC frame self-contained; the viewer replays from a per-frame shared geometry buffer instead of thousands of per-draw allocations.
- Frame-time instrumentation is built in: the runtime log carries a per-120-frame ledger (
frame_ms,draw_mswith hash/upload/submit buckets,present_ms,api_ms,game_ms, draws/frame).
| Stack | Frame time | Notes |
|---|---|---|
| dx9mt @ wine-crossover 23.7.1 + msync | ~68 ms (~15 fps) | smoothest frame pacing; make run-msync |
| dx9mt @ upstream Wine 11 | ~77 ms (~13 fps) | make run |
| wined3d (GL) @ upstream Wine 11 | ~50–55 ms (~18–20 fps) | matched-settings baseline; make run-wined3d |
Menus and light scenes run at 120+ fps on all stacks. The ledger attributes ~50 ms of the dense-exterior frame to the game engine itself under Rosetta 2 (FNV shipped unoptimized, single-thread-heavy); dx9mt's own cost is ~18 ms with known reductions remaining (dirty-region texture tracking, zero-copy viewer buffers, command-stream threading).
FalloutNV.exe (i686 / Wine)
|
v
+------------------------------------+
| d3d9.dll (PE32, MinGW) |
| Implements IDirect3DDevice9 |
| Captures draws, clears, blits, |
| shaders, textures, and state; |
| windowed VB/IB uploads, per-frame |
| bytecode/constants dedup |
+----------------+-------------------+
| packets + 3 x 256MB upload arena refs
v
+------------------------------------+
| Backend Bridge (compiled twice) |
| PE32 inside the DLL, ARM64 inside |
| libdx9mt_unixlib.dylib |
| Validates packets, fails closed on |
| missing payloads, assembles the |
| shared-memory IPC on Present() |
+----------------+-------------------+
| 256MB IPC file (seqlock frames)
v
+------------------------------------+
| Metal Viewer (native ARM64 macOS) |
| Replays draws and StretchRect |
| Translates D3D9 bytecode to MSL |
| (+ alpha-test / fog emulation) |
| Renders via Metal into NSWindow |
+------------------------------------+
The frontend DLL replaces d3d9.dll inside a Wine prefix. Each indexed draw snapshots device state into a packet and uploads exactly the vertex/index window the draw references (index values are rescanned and rebased — the API's MinVertexIndex/NumVertices hints are never trusted). The backend serializes the frame into /tmp/dx9mt_metal_frame.bin; the standalone viewer snapshot-copies and replays it, caching compiled shaders by id and binding geometry from a triple-buffered shared buffer.
make run # build + install DLL + launch FNV (NVSE) + viewer, upstream Wine
make run-msync # same, hosted on wine-crossover FOSS + WINEMSYNC=1 (fastest/smoothest)
make run-wined3d # baseline: Wine's builtin wined3d with fps tracing
make test # backend contract tests
tools/plot_fps.py # chart the newest session's framerate into assets/Sessions log to dx9mt-output/session-*/. In the viewer, press d to dump the current frame for per-draw ground truth.
- Shader translation for SM 1.x–3.0 with write-mask-correct stores,
sincos/texldl/texldd/dsx/dsysupport, and per-shader-id function caches. - Indexed draws, triangle fans (re-indexed to lists),
Clear, offscreen render targets,StretchRect, depth state, blending, scissor, cull, alpha test, table fog, and up to 8 texture stages. - Formats: DXT1/3/5, A8R8G8B8, X8R8G8B8, A8, R32F, A16B16G16R16, A16B16G16R16F.
- Render-target-to-texture linkage so later passes sample earlier offscreen output.
- Diagnostics: per-session runtime/viewer logs with drop counters and the perf ledger, shader/PSO failure artifacts, frame dumps.
- The HDR/imagespace post-process chain is incomplete — the scene lacks the game's color grading (the wasteland "yellow" filter) and bloom.
- No MSAA yet; edges are aliased.
- Texture uploads ride a lossy channel with an 8-frame refresh net; occasional texture pop/flicker until dirty-region tracking + a persistent resource heap land.
- Stencil silently no-ops; mid-frame depth clears collapse to one per frame (minor viewmodel z artifacts); separate-alpha blending is not captured.
DrawPrimitiveand the UP draw calls are no-op stubs (FNV renders viaDrawIndexedPrimitive).- IPC caps at 2,048 draws per frame.
Requires macOS (ARM64), Xcode command-line tools, and an i686-w64-mingw32-gcc cross-compiler.
make -C dx9mt # DLL, backend dylib, viewer
make test # contract tests
# Shader corpus regression (needs the game's Data/Shaders):
cd dx9mt/tests && clang -O2 -I../src/tools -framework Metal -framework Foundation \
corpus_emit_test.m ../src/tools/d3d9_shader_parse.c ../src/tools/d3d9_shader_emit_msl.c \
-o corpus_emit_test && ./corpus_emit_test "<FNV>/Data/Shaders"| Artifact | Arch | Description |
|---|---|---|
build/d3d9.dll |
PE32 (i686) | D3D9 frontend injected into Wine |
build/libdx9mt_unixlib.dylib |
ARM64 | Backend bridge library |
build/dx9mt_metal_viewer |
ARM64 | Standalone Metal frame replay app |
docs/architecture.md: packet, IPC, and viewer architecture (dated March 2026; predates the windowed-upload and emulation work)docs/insights.md: implementation gotchas and debugging notes
MIT License