GlideVK

A native Linux 3dfx Glide → Vulkan translation layer. The Glide equivalent of DXVK / D7VK: drop-in glide3x.dll / glide2x.dll that translate Glide calls directly to Vulkan under Wine — no Direct3D or OpenGL hop.

Status: P3 in progress — real games. glide2x.dll + glide3x.dll shells over a shared core. Deus Ex (Unreal, glide2x) boots, plays its whole intro and shows its main menu with GlideVK: the Eidos and Ion Storm logos, the flying title, the lit metallic emblem and the menu text all render, and in-game resolution changes switch the (Wine-emulated) display mode like a 3dfx driver did (see docs/game-compatibility.md). Behaviour is checked against a reference Glide DLL (nGlide) with examples/run_diff.sh, which found five root causes in a row: Glide's s/t span [0,256) on the major axis, not texels; the blend-factor table was permuted; palettes apply at draw time, not bind time; W-buffer depth comes from oow, not ooz; and the gu combine helpers must expand exactly as the SDK's gu.c does. The Wine smoke tests (examples/run_wine_probe.sh [32|64]) still pass on the 32-bit ship target.

Origin: proposed in lutris/dgvoodoo2#5 as the missing FOSS piece for legacy-API coverage on Linux, alongside D7VK, nGlide, and cncdraw.

Layout

crates/
  glidevk-core/   Backend-agnostic core: Glide state machine, texture format
                  conversion, LFB emulation, state-hash -> pipeline/shader cache.
                  Host-buildable and unit-tested (no Vulkan loader required).
  glide3x/        The glide3x.dll shell — Glide 3.x entry points -> core.
docs/
  feasibility.md  Feasibility study, architecture, and roadmap.

glide2x/ The glide2x.dll shell — Glide 2.x entry points -> core (fixed GrVertex, gu* helpers, inverted texture LOD).

Building

Core (host — for development & tests)

cargo test                       # runs core + shell unit tests natively
cargo check -p glidevk-core --features vulkan   # type-check the ash backend

The core builds on any host so the state machine, texture decode, and LFB packing can be developed and tested without a Vulkan loader.

Differential tests (against a reference Glide DLL)

examples/run_diff.sh                    # wine_texcoord beside nGlide and beside ours, diffed
GLIDE_REF=/path/glide2x.dll examples/run_diff.sh wine_texcoord wine_blendmode
GLIDE_API=glide3x examples/run_diff.sh wine3_palette   # glide3x shell, wine3_* harnesses

Harnesses that read back through grLfbReadRegion run unchanged against any Glide 2 implementation, so the reference defines correct behaviour. See docs/game-compatibility.md § Differential testing.

glide3x.dll (Wine target — the shipping artifact)

Glide games are 32-bit, so the primary target is i686-pc-windows-gnu (x86_64-pc-windows-gnu also builds, for the rare 64-bit consumer):

rustup target add i686-pc-windows-gnu
cargo build -p glide3x --release --target i686-pc-windows-gnu

Exports are forced undecorated via #[export_name] and mirrored in crates/glide3x/glide3x.def for the MinGW linker. Vulkan is reached through the in-prefix vulkan-1.dll → winevulkan, exactly as DXVK does. (x86_64-w64-mingw32-gcc and wine are the runtime prerequisites.)

Install into a Wine prefix (once the backend lands)

cp target/i686-pc-windows-gnu/release/glide3x.dll "$WINEPREFIX/drive_c/windows/system32/"
# then set glide3x to native,builtin as a Wine DLL override

Roadmap

• P0 ✅ — DLL loads under Wine; Vulkan reached via winevulkan; grSstWinOpen builds a Win32 surface + swapchain; grBufferClear/grBufferSwap clear + present. Verified end-to-end (headless probe + 60-frame windowed present).
• P1 ✅ — first triangle: grDrawTriangle / grDrawVertexArray / grDrawVertexArrayContiguous → Vulkan draw (render pass, passthrough Gouraud pipeline, persistently-mapped vertex buffer, grVertexLayout parsing, window→clip transform, primitive assembly for list/strip/fan). Verified via center-pixel readback on 32- and 64-bit.
• P2 ✅ — textures + combine units. grTexDownloadMipMap/grTexSource decode (RGB565/1555/4444/P8/A8/I8) and upload to GPU images with descriptor sets; a combiner ubershader implements the Glide color/alpha combine units driven by push constants (grColorCombine/grAlphaCombine/grTexCombine, GR_PARAM_ST0). Verified via center-pixel readback on 32- and 64-bit. (Chose an ubershader over per-key GLSL→SPIR-V codegen: identical output, and it dodges a naga 30.0 frontend bug — per-state shader specialization is a deferred P4 perf optimization.)
• P3a ✅ — alpha blend (grAlphaBlendFunction), depth buffer (grDepthBufferMode/ Function/grDepthMask, GR_PARAM_Z), alpha test + chroma-key discard. The pipeline cache keys VkPipelines on baked blend/depth state; combine/chroma/ alpha-test are push-constant driven. Verified via center-pixel readback.
• P3b (LFB) ✅ — grLfbLock/grLfbUnlock write path: the game's 16/32-bit framebuffer writes are unpacked (RGB565/555/1555/8888) and composited into the presented image on swap. Verified via examples/wine_lfb.c (LFB-written yellow overwrites a blue clear). This is the path Diablo II's 2D/menus use. Remaining P3b: fog (per-pixel fog blend + table), read-locks / partial-region LFB preservation, and the offscreen-backbuffer model for finely interleaved LFB↔triangle ordering.
• glide2x shell ✅ — crates/glide2x reusing glidevk-core: fixed GrVertex, grSstQueryHardware, inverted texture LOD, and the gu* combine helpers. Exports cover Deus Ex / POD / Undying's glide2x imports, and it renders a textured/combined triangle correctly under Wine (verified via examples/wine_glide2.c). See docs/game-compatibility.md.

Real-game status

• glide2x.dll — verified drop-in for the Unreal-engine games, POD, and the 1997–98 catalogue (covers their import tables; renders through the fixed GrVertex path). Best first real-render target once 64-bit prefixes are in place.
• glide3x.dll — now exports the complete documented Glide 3.x API surface (every entry in glide3x.def has a body — the P0–P3 render path wired to glidevk-core, plus state save/restore, screen/origin queries, single-level texture download, tex-mem accounting, clamp-mode select, and the guFogGenerate* table builders; remaining future-milestone calls — fog render, NCC, region LFB — are accepted no-ops). Verified loadable drop-in for Diablo II (all 35 D2Glide.dll imports); full-frame LFB (P3b) is done, region-LFB is the last piece for its 2D/menus.
• P4 — fidelity (16-bit dither / 22-bit post-filter, NCC textures), performance, HUD/config, Lutris install path.

Licensing

GlideVK code: MIT OR Apache-2.0. The reference material (open 3dfx Glide SDK, SPDX Glide) is a permissive, source-available license permitting derivative works; API semantics and export signatures are taken from it. This is a clean, from-scratch FOSS implementation — the entire point of the originating thread.