Verifiable development environment

Software Vulkan device (lavapipe)

Mesa’s lavapipe is the supported software Vulkan implementation for running GPU-touching code and tests on a machine with no display and no discrete GPU.

• Package: vulkan-swrast on Arch, mesa-vulkan-drivers on Debian/Ubuntu.
• Invocation: set VK_ICD_FILENAMES to the lavapipe ICD json before running. The file name is distro-dependent — on this machine (Arch, vulkan-swrast package) it is /usr/share/vulkan/icd.d/lvp_icd.json (not lvp_icd.x86_64.json; check ls /usr/share/vulkan/icd.d/ for the exact name on your machine).
• Verified: VK_ICD_FILENAMES=/usr/share/vulkan/icd.d/lvp_icd.json vulkaninfo --summary reports a device with vendorID = 0x10005 (Mesa’s lavapipe vendor ID).

Shader compiler for the determinism check

--features gpu-tests also runs simulation_shaders_are_precise_and_never_relaxed, which compiles the physics shaders with glslc and scans the SPIR-V (see docs/determinism.md). Install shaderc on Arch, glslc on Debian/Ubuntu, or the Vulkan SDK; glslc --version must work.

Device requirements

Windows open through vulkano_util::VulkanoContext, configured by rendering::vulkano_config (src/rendering/mod.rs). It requests only:

• Instance extensions: the platform surface extensions, plus ext_debug_utils / ext_validation_features when the Khronos validation layer is present (debug builds, or any build with the validation feature).
• Device extensions: khr_swapchain.
• Device features: sampler_anisotropy when the device supports it.

Lavapipe supports khr_swapchain and presents to a real window via the X11 or Wayland surface extensions like any other ICD, so the engine’s existing windowed startup path runs unmodified under it — no headless-specific code exists yet (see the “Headless mode” and RUSTING_VULKAN_DEVICE items in roadmap.md Milestone 0.5, which are not implemented).

Iteration speed

The engine’s target for a representative project is 3 seconds or less from a Rust edit to the first frame of the running game, as an incremental Debug build. The representative project is the starter template (rusting new <dir> "Coin Run" --template starter). tests/iteration_latency.rs checks the target and prints a report:

cargo test --test iteration_latency -- --ignored --nocapture

The test runs rusting run --ticks 1 --json and reads data.timings. Each timing starts when the command starts and ends at the game’s first frame, so it covers cooking, the cargo build and game startup. The test reports the median of three samples. Set RUSTING_LATENCY_REPORT=<file> to also write the report as JSON.

Measured on 2026-09-28 (Linux, AMD Ryzen 5 7600X, NVIDIA RTX 3060, headless, shared target/cli-games build directory):

In the editor, Reload Code measured 1.35 s from the click to the first frame of the restarted game, with its window, for a generated 3D project. The editor Console prints this time after each Play and each reload.