erhe

A C++ 3D graphics library and sandbox editor, with a Vulkan/Metal-style rendering abstraction over OpenGL, Vulkan, and Metal.

erhe is an actively-developed personal research project for real-time rendering and geometry. Its editor is a sandbox for 3D scene creation, manipulation, and procedural mesh generation. erhe is the evolution of RenderStack.

git clone https://github.com/tksuoran/erhe
cd erhe

# Windows (from an x64 Native Tools Command Prompt)
scripts\configure_vs2026_vulkan.bat

# Linux
scripts/configure_ninja_linux_vulkan.sh && cmake --build build_ninja_linux_vulkan --target editor

# macOS
scripts/configure_xcode_metal.sh && cmake --build build_xcode_metal --target editor --config Debug

Vulkan is the default backend; the OpenGL build uses the *_opengl scripts instead (e.g. scripts\configure_vs2026_opengl.bat). See doc/building.md for all backends, CMake options, and IDE setup.

The OpenGL backend requires OpenGL 4.5 (with Direct State Access) at minimum; 4.6 is recommended. It is not available on Apple platforms.

The editor is a sandbox application for 3D scene creation and manipulation.

• Multiple 3D viewports with independent camera and rendering settings
• Hierarchical scene graph with node parenting
• glTF import and export
• Partial USD support: open, edit and save .usd / .usda / .usdc / .usdz stages, with references and payloads shown as prefab instances, variant sets, class prims as styles, and UsdPhysics / UsdSkel content
• Scenes save as a single glTF binary carrying ERHE_* extensions, or as USD; a scene stays in the format it was opened from
• Multi-scene support
• Post-processing pipeline (bloom, tonemapping)
• Shadow mapping
• PBR material system with metallic/roughness workflow
• Material library with preview rendering

• Fly camera -- 6DOF camera navigation with WASD, orbit, tumble, track, zoom
• Selection -- click-to-select with shift/ctrl multi-select, GPU ID buffer or raytrace picking
• Transform gizmo -- translate, rotate, scale with axis/plane constraints and snapping
• Brush placement -- place shapes on surfaces with snap-to-face, rotation, and scale-to-match
• Vertex painting -- paint vertex colors directly on meshes
• Material painting -- assign materials to individual mesh faces
• Physics interaction -- drag, push, and pull rigid bodies in the scene
• Grid -- configurable grid display and snap-to-grid

• Subdivision: Catmull-Clark, sqrt3
• Conway operators: ambo, chamfer, dual, gyro, join, kis, meta, truncate, chamfer/bevel
• CSG / boolean: union, intersection, difference (experimental, via Geogram)
• Utilities: triangulate, normalize, reverse, weld, repair, generate tangents, bake transform
• Full undo/redo for all operations

• Parametric shapes: sphere, box, cone, torus, disc, cylinder
• Brush system with reusable shape templates
• 180+ built-in polyhedra (Platonic solids, Johnson solids, geodesic domes, etc.)
• Procedural scene generation

• Texture graph -- Material Maker-style procedural texture authoring with ~75 node types (noises, patterns, gradients, transforms, color operations); nodes compose into a single fragment shader evaluated on the GPU, with live per-node previews, and bake to textures and PBR material channels
• Geometry graph -- node-based procedural modeling: parametric generators, subdivision, Conway operators, lattice deform, boolean CSG, point scattering and instancing, nested node groups; evaluated asynchronously on worker threads so editing stays interactive
• Shared node-editor canvas with a dockable node palette, undo/redo, and JSON serialization; graphs are content-library assets

• CPU ray tracing library with swappable backends (madmann91 bvh, tinybvh, Embree 4) and BVH disk caching, used for mouse picking and spatial queries
• GPU ray tracing renderer (Vulkan ray query compute): PBR material shading, real scene lights, ray-traced shadows, reflection and refraction for transmissive materials

• glTF 2.0 import and export (via fastgltf), including KHR_physics_rigid_bodies, KHR_materials_variants and the erhe-specific ERHE_* extensions
• Partial OpenUSD import and export (via LightUSD; optional, ERHE_USD_LIBRARY=lightusd): meshes, UsdPreviewSurface and OpenPBR materials, cameras, lights, xformOp stacks, time samples, skinning, physics, point instancers, composition arcs and variants; MaterialX documents are not read. See doc/erhe/usd_compatibility.md
• Partial support for Wavefront OBJ import

• Headset rendering with OpenXR
• Hand and controller tracking with visualization
• Floating HUD and hotbar UI in VR
• Passthrough support

• Keyboard and mouse with configurable bindings
• SpaceMouse 6DOF input
• OpenXR controllers

• Debug line and text rendering in 3D viewports
• Physics shape visualization
• Render graph visualization window
• Shader hot-reload via shader monitor
• GL state dump to clipboard
• Tracy profiler integration

The editor embeds an MCP server (JSON-RPC over HTTP on 127.0.0.1:3743), so AI agents and scripts can drive a running editor. It works in the windowed build, in the headless build (no display needed) and on Quest over adb forward. See doc/agents/mcp_server_usage.md for the API reference.

• Scene queries -- scenes, nodes, cameras, lights, materials, textures, brushes, selection, undo/redo stack, physics items, async load status
• Scene editing -- create shapes and nodes, place brushes, select, transform, reparent, edit materials, geometry operations, mesh component (face / edge / vertex) editing, physics bodies and joints, node graphs; edits go through the undo stack
• Properties -- generic read / write access to the registered properties of any item, including styles and expressions
• Files -- open, save and close scenes; glTF and USD import and export
• Screenshots -- the editor's own composited frame, in both windowed and headless builds, optionally annotated with ImGui item rectangles
• ImGui introspection -- list ImGui hosts, windows and items with their rectangles, and click, hover or scroll an item addressed by its label
• Input event injection -- mouse clicks, drags and wheel, key presses and text are injected as real window input events, so menus, docking, property rows, gizmo drags and viewport gestures are driven the way a user drives them; see the UI driving run-book
• All registered editor commands (undo, redo, delete, ...) are callable as tools
• The MCP test suite (mcp_server_tests) and the scene round-trip verification scripts run against this server
• AI creations catalogs agent-built showcase scenes and the editor features each exercises

erhe is organized as a set of independent libraries under src/erhe/. Each has a doc/erhe/<name>.md document with details on purpose, API, and design; doc/README.md indexes them.

erhe requires OpenGL 4.5 with DSA (Direct State Access); device creation fails on older versions. DSA, SSBOs, compute shaders and clip control are used unconditionally. The former OpenGL 4.1 (macOS) runtime compatibility layer has been removed.

All documentation lives under doc/; doc/README.md states the layout and indexes every document with its stability level.

erhe's own source is MIT-licensed -- see src/erhe/LICENSE. Bundled and fetched third-party dependencies retain their own licenses; see License.txt for the overview.

erhe stands on many excellent open-source projects. Most are fetched at configure time via CPM.cmake; some are in-tree copies under src/. Several are pulled from erhe-specific forks of the listed upstream. Entries marked optional are used only when the matching CMake option selects them (see doc/building.md). Each dependency retains its own license; the table names it in short form and the dependency's own license file is authoritative.

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