giha

giha is a playground for experimenting with dart-based geometry processing on Slang. The project focuses on implementing cyclic permutations of connectivity representations for geometry processing workflows.

Features

• Dart-based combinatorial model
  • A relaxed-condition half-edge structure allowing multiple edges (include/giha/geometry/dart.h).
  • Converts sparse face-vertex incidence lists into a canonical dart structure via a SpGEMM-like stitch phase (include/giha/geometry).
• Reference kernels — Runnable compute-kernel geometry-processing algorithms.
  • Dart-based structure for connectivity and induced maps
  • Orbit collector topology query
  • Loop-like subdivision
  • Delaunay triangulation pass
  • Spatial acceleration construction and its query (e.g., BVH, KD-tree)

Repository layout

include/            # Public C++ headers (geometry, linalg, slang helpers)
module/             # Slang modules and kernels
src/                # Host-side runtime and Slang helpers
test/               # Optional tests (enable with GIHA_TEST)
cmake/              # Helper scripts (e.g., DownloadGithubRelease.cmake)

Key building blocks:

• module/giha/geometry/dart.slang mirrors the dart map on the GPU and adds mutable/atomic variants suited for lock-free edits.
• module/giha_kernel, … Compute kernels for geometry processing against the combinatorial model.
• include/giha/slang hosts the slang compile binder.
• include/giha/slang/adapters hosts descriptors that bind dart buffers into RHI pipelines (easy to use or for test).

Build requirements

• CMake ≥ 3.25
• A C++20 compiler (MSVC, clang, or gcc)
• Optional: GPU + Slang for shader compilation (downloaded automatically when GIHA_SLANG=ON, the default).
• Optional: slang-rhi (fetched automatically when GIHA_SLANG_RHI=ON).

Configure & build

# 1. Configure (defaults: GIHA_SLANG=ON, GIHA_SLANG_RHI=OFF, GIHA_TEST=OFF)
cmake -S . -B build \
  -DGIHA_SLANG=ON \
  -DGIHA_SLANG_RHI=OFF \
  -DGIHA_TEST=OFF

# 2. Build
cmake --build build

Useful options:

Option	Default	Description
GIHA_SLANG	ON	Enable Slang support and download the matching SDK.
GIHA_SLANG_RHI	OFF	Build slang-rhi adapters/kernels (downloads slang-rhi).
GIHA_TEST	OFF	Build the test suite in test/.
GIHA_LOG_LEVEL	3	Compile-time log verbosity (0 silent … 3 debug).

Set options at configure time, e.g. -DGIHA_TEST=ON.

Tests

cmake -S . -B build -DGIHA_TEST=ON
cmake --build build
cmake --build build --target test   # or: ctest --test-dir build

Tests rely on slang-rhi, so enabling them forces GIHA_SLANG_RHI=ON inside test/CMakeLists.txt.

Running kernels

1. Build with GIHA_SLANG_RHI=ON so the slang-rhi runtime is available.
2. Use the adapters in include/giha/geometry/adapters/slang-rhi/ to upload a giha::DartMap into GPU buffers and bind them into a shader cursor.
3. Compile the desired kernels from module/giha_kernel/*.slang (e.g., orbit collectors or subdivision) using giha::kernel helpers (include/giha/slang/slang.h).
4. Dispatch through slang-rhi’s ComputeKernel wrapper (src/slang/adapters/slang-rhi.cpp).

See module/giha_kernel/subdivide.slang for a complete in-shader example of inserting darts, connecting orbits, and updating induced vertex keys.

References

• Slang — shading language & compiler used for GPU kernels.
• slang-rhi — rendering hardware interface leveraged by the runtime adapters.

License

Distributed under the MIT License; see LICENSE for details.