OHAO Engine

OHAO Engine is a custom physics and rendering engine that integrates with Godot 4.x as a GDExtension. It features a Vulkan-based renderer and custom physics simulation.

Architecture

OHAO Engine runs as a GDExtension plugin inside Godot Editor, providing:

• Custom Vulkan offscreen renderer (renders to texture displayed in Godot)
• Custom physics simulation
• Actor-component system for scene management

Godot Editor
    │
    ▼
OhaoViewport (GDExtension)
    │
    ├─ OffscreenRenderer (Vulkan)
    │     └─ Renders scene to pixel buffer
    │
    └─ Scene/Actor/Component system
          └─ Custom physics simulation

Building

Prerequisites

macOS:

• Xcode Command Line Tools
• CMake 3.20+
• Vulkan SDK (via MoltenVK from Homebrew)
• SCons (for GDExtension)
• Godot 4.x

# Install dependencies on macOS
xcode-select --install
brew install cmake vulkan-loader molten-vk scons

Linux:

• CMake 3.20+
• Vulkan SDK
• SCons
• Godot 4.x

# Install dependencies on Ubuntu/Debian
sudo apt install cmake libvulkan-dev scons

Clone the Repository

git clone --recursive https://github.com/Qervas/ohao-engine.git
cd ohao-engine

# Or if you already cloned without --recursive:
git submodule update --init --recursive

Build Steps

1. Build Engine Libraries

mkdir -p build && cd build
cmake ..
make -j$(nproc)  # Linux
make -j8         # macOS

2. Build GDExtension

cd godot_editor
scons platform=macos arch=arm64    # macOS Apple Silicon
scons platform=macos arch=x86_64   # macOS Intel
scons platform=linux arch=x86_64   # Linux

3. Run in Godot Editor

cd godot_editor/project
godot -e

The OHAO Viewport tab will appear in the Godot Editor, displaying the custom Vulkan renderer output.

Controls (in OHAO Viewport)

• Arrow Keys: Orbit camera (pitch/yaw)
• W/S: Zoom in/out
• A/D: Pan left/right
• Q/E: Pan up/down

Project Structure

ohao-engine/
├── src/
│   ├── engine/          # Actor-component system, scene management
│   │   ├── actor/       # Entity system
│   │   ├── asset/       # Asset loading
│   │   ├── component/   # Mesh, Transform, Light, Physics components
│   │   └── scene/       # Scene management & loaders
│   ├── physics/         # Custom physics engine
│   │   ├── collision/   # Broad/narrow phase collision
│   │   ├── dynamics/    # Rigid body dynamics
│   │   ├── constraints/ # Physics constraints
│   │   └── world/       # Physics world management
│   ├── renderer/        # Vulkan rendering
│   │   ├── offscreen/   # Headless Vulkan renderer
│   │   ├── camera/      # Camera system
│   │   └── material/    # Material system
│   └── ui/              # Logging utilities
├── godot_editor/        # GDExtension for Godot 4.x
│   ├── src/             # GDExtension source (OhaoViewport, etc.)
│   ├── godot-cpp/       # Godot C++ bindings (submodule)
│   └── project/         # Godot project with OHAO plugin
├── shaders/             # GLSL shaders (compiled to SPIR-V)
└── external/            # External dependencies

Development Status

• Vulkan offscreen rendering
• GDExtension integration with Godot 4.x
• Actor-component system
• Custom physics simulation
• Camera controls in viewport
• Full PBR material rendering (Cook-Torrance GGX BRDF)
• Scene synchronization from Godot
• Shadow mapping (PCF soft shadows)
• Multi-frame rendering (3 frames in flight)
• Cascaded Shadow Maps (CSM)
• Deferred rendering pipeline
• Image-Based Lighting (IBL)

Documentation

• Architecture Overview - System design, diagrams, rendering pipeline
• Bug Fixes History - Solved issues and their solutions
• Changelog

License

MIT License

Author

Qervas

Acknowledgments

• Godot Engine - Game engine and editor
• Vulkan - Graphics API
• MoltenVK - Vulkan on macOS