SimpleRenderer

An educational C++ software renderer designed to help developers understand the inner workings of rendering pipelines and how OpenGL operates behind the scenes.

Overview

SimpleRenderer is a software renderer built with the primary goal of educating developers about the fundamentals of 3D rendering and graphics pipelines. By providing a simplified yet functional rendering framework, it demystifies the complex processes involved in rendering graphics, mirroring how OpenGL and other graphics APIs work under the hood.

Purpose

• Educational Focus: Designed to teach the core concepts of rendering, including vertex processing, rasterization, shading, and transformations.
• Demystifying OpenGL: Offers insights into how OpenGL and GPU-based rendering pipelines function internally.
• Hands-On Learning: Allows developers to experiment with rendering algorithms and observe the effects of various techniques in real-time.

Key Features

• Customizable Shaders: Implemented vertex and fragment shaders to demonstrate how shading works at a fundamental level.
• Simplified Rendering Pipeline: Breaks down the rendering process into understandable stages, mirroring the OpenGL pipeline.
• Cross-Platform Compatibility: Compatible with Linux and macOS, facilitating learning across different environments.
• Extensive Documentation: Provides detailed explanations of each component to aid learning and comprehension.

Learning Objectives

By exploring SimpleRenderer, you will learn:

• How vertices are transformed from 3D space to 2D screen coordinates.
• The process of assembling primitives (triangles) and performing clipping.
• How rasterization converts vector information into pixels.
• The fundamentals of shading models, including lighting calculations.
• How depth buffering and backface culling optimize rendering.

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Getting Started

Prerequisites

Ensure you have the following dependencies installed:

sudo apt install doxygen graphviz clang-format clang-tidy cppcheck lcov gcc g++ libsdl2-dev libsdl2-ttf-dev libomp-dev libspdlog-dev cmake libassimp-dev

For macOS users, install dependencies using Homebrew:

brew install doxygen graphviz clang-format clang-tidy cppcheck lcov gcc sdl2 sdl2_ttf libomp spdlog cmake assimp

Building the Project

1. Clone the Repository

git clone https://github.com/Simple-XX/SimpleRenderer.git
cd SimpleRenderer

2. Configure and Build Using CMake Presets

For a standard build:

cmake --preset=build
cmake --build build --target all

For macOS:

cmake --preset=build-macos
cmake --build build-macos --target all

3. Run the Example Application

./build/bin/system_test ../obj

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Understanding the Renderer

Core Rendering Pipeline

The rendering pipeline in SimpleRenderer is designed to mirror the stages of a typical GPU-based pipeline, providing a clear view of how each component contributes to the final rendered image.

1. Vertex Processing and Transformations

   • Objective: Understand how 3D models are projected onto a 2D screen.
   • Key Concepts:
     • Model Matrix: Positions and orients models in the world.
     • View Matrix: Represents the camera's position and orientation.
     • Projection Matrix: Defines the camera's lens (field of view, aspect ratio).

2. Primitive Assembly and Clipping

   • Objective: Learn how individual vertices form triangles and how off-screen parts are handled.
   • Key Concepts:
     • Triangle Assembly: Grouping vertices into drawable primitives.
     • Clipping: Discarding or adjusting primitives outside the view frustum.

3. Rasterization and Fragment Processing

   • Objective: Discover how triangles are converted into pixel data.
   • Key Concepts:
     • Barycentric Coordinates: Used for interpolating vertex attributes across a triangle.
     • Depth Buffering: Ensures correct rendering of overlapping objects.
     • Fragment Shaders: Calculate the color and other attributes of each pixel.

4. Shading and Lighting Models

   • Objective: Explore how lighting affects the appearance of surfaces.
   • Key Concepts:
     • Phong Shading Model: Simulates realistic lighting with ambient, diffuse, and specular components.
     • Surface Normals: Determine how light interacts with surfaces.
     • Light Sources: Understand different types of lights (directional, point, ambient).

5. Optimization Techniques

   • Objective: Learn methods to improve rendering efficiency.
   • Key Concepts:
     • Backface Culling: Eliminates faces not visible to the camera.
     • Spatial Partitioning: Organizes objects to reduce rendering workload.

Code Structure

• src/rasterizer.cpp

  Focuses on the rasterization process, converting vector data into raster images. Key learning points include:

  • Implementing barycentric interpolation.
  • Managing depth buffering.
  • Handling edge cases in rasterization.

• src/renderer.cpp

  Orchestrates the rendering process. Highlights include:

  • Setting up transformation matrices.
  • Managing the rendering loop.
  • Integrating shaders and handling user input.

• src/include/

  Contains header files with detailed comments explaining the purpose and functionality of classes and methods.

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Experimentation and Learning

To maximize learning, consider the following steps:

• Modify Shaders

  Experiment with the shader code to see how changes affect rendering.

• Adjust Transformations

  Play with the model, view, and projection matrices to understand their impact on the scene.

• Implement New Features

  Try adding new lighting models, textures, or shading techniques.

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Documentation

Generate the documentation to delve deeper into the codebase:

cmake --build build --target doc
xdg-open doc/html/index.html

The documentation provides detailed explanations and diagrams to enhance understanding.

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Contributions

Your contributions can help others learn. Feel free to:

• Submit pull requests with improvements or new educational features.
• Report issues or suggest enhancements.
• Share your learning experiences.

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License

This project is licensed under the MIT License. See the LICENSE file for more information.