Pyre – Graphics Engine

Pyre is a modular, educational 3D graphics engine built from scratch using Modern OpenGL and C++20. Inspired by the brilliant work behind LearnOpenGL, Pyre explores advanced real-time rendering concepts, including Instancing, Geometry Shaders, Post‑Processing, and Toon Shading.

It features a custom CMake build system that automatically fetches and configures dependencies like GLFW and Assimp, making the engine cross‑platform and effortless to build.

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📸 Visual Showcase

See Pyre's rendering features in action.

Standard Blinn-Phong Lighting	Cel-Shading (Toon)
Classic lighting model with multiple light sources.	Stylized rendering with rim lighting and distinct bands.

Instanced Rendering (1M+ Meshes) at 144+ fps	Post-Processing (Inversion)
Instanced Rendering using vertex atrrib model matrices.	Framebuffer-based inversion effect with ping pong post processing.

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✨ Features

🎨 Rendering Pipeline

• Modular Shaders: Custom preprocessor enabling #include directives inside GLSL.
• Lighting: Blinn‑Phong lighting supporting Directional, Point, and Spotlights, powered by Uniform Buffer Objects (UBOs).
• Instanced Rendering: Efficient rendering for thousands of identical meshes (e.g., asteroid fields, particle clouds).
• Geometry Shaders: Used for normal visualization and dramatic mesh explosion effects.
• Post‑Processing Stack: Framebuffer‑based pipeline supporting Inversion, Grayscale, Sharpening, and Outline detection.
• Toon Shading: Cel‑shaded rendering with stylized rim‑lighting.

🛠 Core Architecture

• Entity‑Component Layout: Entity, MeshRenderer, ModelRenderer for clean object representation.
• Centralized Asset Manager: Texture caching, model loading, and safe path handling.
• Scene System: Hot‑swappable environments (Factory, Backpack, Toon, Test) controlled via a global application state.
• Debug Utilities: Wireframe mode, shader hot‑reload, and visual debugging tools.

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💻 Prerequisites

Before building Pyre, ensure these tools are installed:

• C++20 Compiler
  • Windows → Visual Studio 2022 (MSVC)
  • Linux → GCC 10+ or Clang 10+
  • macOS → Xcode Command Line Tools
• CMake ≥ 3.16
• Git

You do not need to install GLFW, Assimp, GLM, or GLAD manually — the CMake script does everything.

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🔨 Build & Installation

Option A – Visual Studio 2022 (Recommended)

1. Clone the repository.

2. Open Visual Studio.

3. Select Open a Local Folder and choose pyre.

4. Let VS detect and configure CMakeLists.txt.

5. Select Pyre.exe as the startup target and press F5 to run.

Option B – Command Line (Windows / Linux / macOS)

# Clone the repository

git clone https://github.com/Open-Source-Chandigarh/pyre.git

cd pyre



# Create a build directory

mkdir build && cd build



# Configure (downloads third‑party dependencies)

cmake ..



# Build

cmake --build . --config Debug

Run the Engine

# Windows

.\/Debug\/Pyre.exe



# Linux / macOS

./Pyre

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🎮 Controls

Key             Action

W, A, S, D       Move Camera

Mouse            Look Around

Scroll           Adjust FOV

Right Arrow      Next Scene

Left Arrow       Previous Scene

F                Toggle Wireframe

R                Reset Camera

ESC              Lock/Unlock Mouse

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📂 Project Structure

Pyre/

├── CMakeLists.txt            # Build configuration

├── .gitignore                # Ignore build artifacts

├── src/                      # Engine source

│   ├── main.cpp              # Entry point & game loop

│   ├── core/                 # Engine internals

│   │   ├── rendering/        # Renderer, Mesh, Model, FBO

│   │   │   └── geometry/     # Procedural shapes (Cube, Sphere, Torus)

│   │   ├── Window.cpp        # GLFW window wrapper

│   │   └── InputManager.cpp  # Input processing

│   └── scenes/               # Example scenes

├── includes/                 # Public headers

│   ├── core/                 # Engine interfaces

│   ├── scenes/               # Scene declarations

│   └── thirdparty/           # GLAD, stb_image, etc.

├── shaders/                  # GLSL programs

│   ├── modularVertex.vs      # Vertex uber-shader

│   ├── modularFragment.fs    # Lighting uber-shader

│   ├── includes/             # Shared GLSL modules

│   └── postprocessing/       # Screen effects

└── resources/                # Assets

    ├── models/               # OBJ files

    └── textures/             # Diffuse/specular maps, skyboxes

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🤝 Contributing

Want to implement Shadow Mapping, Normal Mapping, or optimizations?

git checkout -b feature/AmazingFeature

# implement your changes

git commit -m "Add AmazingFeature"

git push origin feature/AmazingFeature

Then open a Pull Request.

If you’d like to contribute, please read the CONTRIBUTING.md.

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🙌 Credits

• Joey de Vries – Creator of LearnOpenGL

• GLFW, GLAD, GLM, Assimp, stb_image – The tech stack powering Pyre

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📄 License

Licensed under the MIT License. See the LICENSE file for details.