A Roc platform for creating simple graphics applications.

• 2D drawing primitives (rectangles, circles, lines, text)
• Mouse input handling (position, buttons, wheel)
• Cross-platform support (macOS, Linux, Windows, Web/WASM)
• Native rendering via raylib, web rendering via Canvas 2D

• Zig 0.15.2 or later
• Roc

First, build the platform and cross-compile the pre-built host libraries for all supported targets:

zig build

Then run an example:

roc examples/hello_world.roc

For web/WASM, build with the wasm32 target and serve the files:

roc build --target=wasm32 examples/hello_world.roc

Helper scripts are available to build and serve WASM:

# Linux/macOS
./build_wasm.sh examples/hello_world.roc

# Windows (PowerShell)
.\build_wasm.ps1 examples\hello_world.roc

Run Zig unit tests and WASM integration tests:

zig build test

Run all Roc example tests (check, format, test, build, simulation):

python3 ci/all_tests.py

Enable the pre-commit hook (run once after cloning):

git config core.hooksPath .githooks

RocRay includes a simulation recording and replay system for deterministic testing of graphical applications. This enables regression testing without requiring a display—useful for CI environments.

1. Record a session while running the app normally—inputs (mouse position, buttons, frame count) and outputs (draw commands) are captured to a .rrsim file
2. Replay the session visually to debug or inspect what was recorded
3. Test headlessly by re-running the app with recorded inputs and verifying outputs match

# Build and run the app with recording enabled
roc build examples/hello_world.roc
SIM_RECORD=examples/hello_world_1.rrsim ./examples/hello_world

# Interact with the app, then close the window
# The .rrsim file is written on exit

# Headless verification—exits 0 if outputs match, 1 if mismatch
SIM_TEST=examples/hello_world_1.rrsim ./examples/hello_world

# With full mismatch log for debugging
SIM_TEST=examples/hello_world_1.rrsim SIM_LOG=mismatches.log ./examples/hello_world

In CI, simulation tests run automatically for any .rrsim files found in examples/. The naming convention <app>_<n>.rrsim maps to <app>.roc.

./bundle.sh

This creates a .tar.zst bundle containing all .roc files and prebuilt host libraries. To use a Roc package bundle it should be hosted online with a https: url.

• We vendor the pre-compiled libraries from raylib v5.5
• ARM Linux is not available (raylib doesn't provide pre-built libraries)

• Extend simulation recording/replay/testing to WASM target for browser-based deterministic testing