Mini-Engine

A comprehensive 3D graphics engine showcasing advanced real-time rendering techniques with OpenGL 4.3.

What is Mini-Engine?

Mini-Engine is an advanced graphics learning project that demonstrates modern real-time rendering techniques. It has evolved from basic triangle rendering to a sophisticated engine featuring PBR materials, shadow mapping, deferred rendering, and cluster-based lighting optimizations.

Features

Core Graphics Pipeline

• OpenGL 4.3 with modern core profile
• Deferred rendering for efficient multi-light scenes
• Cluster-based deferred shading supporting 10,000+ lights with zero FPS drop
• Compute shaders for cluster grid calculations and light culling

Advanced Lighting & Shading

• Physically Based Rendering (PBR) with metallic-roughness workflow
• Image Based Lighting (IBL) with:
  • Diffuse irradiance mapping
  • Specular reflection with prefiltered environment maps
  • BRDF integration lookup table
• Direct lighting: Directional, point, and spot lights
• Blinn-Phong and PBR BRDF shading models

Shadow Mapping

• Real-time shadow mapping with PCF (Percentage Closer Filtering)
• Point light shadows using geometry shaders and cube maps
• Directional light shadows with orthographic projection
• Shadow acne elimination and bias correction
• Smooth shadow edges with multi-sample filtering

Post-Processing Effects

• HDR rendering with tone mapping operators
• Bloom effect with gaussian blur
• SSAO (Screen Space Ambient Occlusion) for realistic ambient shading
• Gamma correction for proper color space handling

Asset Loading & Scene Management

• glTF 2.0 model loading using TinyGLTF
• KHR_lights_punctual extension support for scene lighting
• Sponza scene with full material and lighting setup
• Multiple texture support (albedo, normal, metallic-roughness)

Rendering Optimizations

• Frustum culling and light volume optimization
• Face culling and depth testing
• Instanced rendering for repeated geometry
• Light volume spheres for deferred rendering optimization

Technical Features

• Advanced shader system with uniform management
• Framebuffer objects for multi-pass rendering
• Cubemap support for skyboxes and environment mapping
• Dynamic window resizing with proper viewport management
• Debug visualization for shadow maps and light volumes

Rendering Techniques Demonstrated

1. Forward Rendering → Deferred Rendering → Cluster Deferred Rendering
2. Basic Lighting → PBR Materials → IBL Environment Lighting
3. No Shadows → Shadow Maps → Multi-light Shadows
4. LDR → HDR → Tone Mapping & Bloom
5. Simple Geometry → Complex Models → glTF Scene Loading

Project Evolution (Latest Commits)

• Current: Sponza scene with directional lighting and shadow mapping
• PBR & IBL: Full physically-based materials with environment lighting
• SSAO: Screen-space ambient occlusion for realistic depth perception
• Cluster Shading: 10,000+ light support with compute shader optimization
• Deferred Pipeline: Multi-pass rendering for complex lighting scenarios
• Shadow Systems: Real-time shadows for directional and point lights
• HDR Pipeline: High dynamic range with bloom and tone mapping

How to Build and Run

Prerequisites

# Install dependencies (Ubuntu/Debian)
sudo apt-get install build-essential cmake libglfw3-dev libglew-dev libglm-dev

Build

mkdir -p build
cd build
cmake ..
make -j$(nproc)

Run Different Demos

# Main Sponza scene with PBR and shadows
./sponza

# Deferred rendering demo
./deffered_rendering

# Cluster deferred shading (10k lights)
./cluster_deffered_rendering

# HDR and bloom demo
./hdr

# Basic lighting examples
./lighting_main

Controls

Camera

• W/A/S/D: Move forward/left/backward/right
• Mouse: Look around (FPS-style)
• Scroll wheel: Zoom in/out
• Tab: Toggle mouse cursor for UI interaction

Debug Controls

• L: Toggle light cube visualization
• O: Toggle SSAO debug view (where available)
• ESC: Exit application

Scene Assets

Sponza Scene

• Location: resources/main-sponza/main_sponza/
• Format: glTF 2.0 with PBR materials
• Features:
  • High-quality textures (albedo, normal, metallic-roughness)
  • Scene lighting with KHR_lights_punctual
  • Complex architecture for shadow testing

Environment Maps

• HDR Environment: resources/newport_loft.hdr
• Skybox textures: resources/skybox/

Technical Architecture

Shaders

• Vertex/Fragment: Traditional pipeline stages
• Geometry: Point light shadow mapping
• Compute: Cluster grid generation and light culling

Framebuffers

• G-Buffer: Position, normal, albedo, material properties
• Shadow Maps: Depth textures for shadow calculations
• HDR Buffer: High dynamic range color storage
• Bloom: Multi-pass gaussian blur

Dependencies

• GLFW 3.3+: Window management and input
• GLAD: OpenGL function loading
• GLM: Mathematics library for graphics
• stb_image: Image loading (PNG, JPG, HDR)
• TinyGLTF: glTF 2.0 model loading
• Dear ImGui: Debug UI (in some demos)

Performance Notes

• Cluster Deferred: Handles 10,000+ lights at 60+ FPS
• Shadow Maps: 1024x1024 depth maps with PCF
• SSAO: Full-screen effect with configurable samples
• PBR: Real-time IBL with precomputed environment maps

Future Enhancements

• Temporal Anti-Aliasing (TAA)
• Screen Space Reflections (SSR)
• Volumetric lighting and fog
• Animation system for glTF models
• Real-time global illumination

Learning Resources

Each major technique is implemented in separate demos, making it easy to understand the progression from basic to advanced rendering. Check the docs/ directory for detailed explanations of specific techniques.

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This project demonstrates the evolution from basic OpenGL rendering to production-quality real-time graphics techniques.