SoftGLRender

Tiny C++ software renderer/rasterizer that implements the main steps of the GPU rendering pipeline, including point, line and polygon rasterization, texture mapping, depth testing, color blending, etc., and emulates vertex shaders and fragment shaders using C++, 3D models (GLTF) are loaded by Assimp, and using GLM as math library. The project also adds OpenGL and Vulkan renderers implementation, you can switch between them (Software/OpenGL/Vulkan) in real time while running.

The purpose of this project is to provide a starting point for developers who want to learn about modern graphics programming.

Examples

Features

Software Renderer

Pipeline

• Vertex shading
• View Frustum culling (line & triangle)
• Perspective Correct Interpolation
• Back-Front face culling
• Point/Line/Triangle rasterization
• Fragment Shading
• Shader derivative dFdx dFdy
• Depth test & Alpha blending
• Early Z test & Reversed Z
• MSAA 4x

Texture Mapping

• Mipmaps generation and sampling
• Sample parameters: Lod, Bias, Offset
• All kinds of texture filtering & wrapping mode
• Image storage tiling and swizzling
  • Linear: pixel values are stored line by line, commonly used as image RGBA buffer
  • Tiled: block base storage, inside the block pixels are stored as Linear
  • Morton: block base storage, inside the block pixels are stored as morton pattern (similar to zigzag)

Optimization

• Multi-Threading: rasterization is block based with multi-threading support
• SIMD: barycentric coordinate calculation, shader's varying interpolation, etc.

Viewer

• Config panel based on imgui
• Orbit camera controller
• Blinn-Phong shading
• PBR & IBL shading
• Skybox cubeMap & equirectangular
• Shadow mapping
• FXAA anti-aliasing
• RenderDoc in-application frame capture

Renderer abstraction

All renderers (Software/OpenGL/Vulkan) are implemented based on this abstract renderer class:

class Renderer {
 public:
  // framebuffer
  std::shared_ptr<FrameBuffer> createFrameBuffer(bool offscreen);

  // texture
  std::shared_ptr<Texture> createTexture(const TextureDesc &desc);

  // vertex
  std::shared_ptr<VertexArrayObject> createVertexArrayObject(const VertexArray &vertexArray);

  // shader program
  std::shared_ptr<ShaderProgram> createShaderProgram();

  // pipeline states
  std::shared_ptr<PipelineStates> createPipelineStates(const RenderStates &renderStates);

  // uniform
  std::shared_ptr<UniformBlock> createUniformBlock(const std::string &name, int size);
  std::shared_ptr<UniformSampler> createUniformSampler(const std::string &name, const TextureDesc &desc);

  // pipeline
  void beginRenderPass(std::shared_ptr<FrameBuffer> &frameBuffer, const ClearStates &states);
  void setViewPort(int x, int y, int width, int height);
  void setVertexArrayObject(std::shared_ptr<VertexArrayObject> &vao);
  void setShaderProgram(std::shared_ptr<ShaderProgram> &program);
  void setShaderResources(std::shared_ptr<ShaderResources> &uniforms);
  void setPipelineStates(std::shared_ptr<PipelineStates> &states);
  void draw();
  void endRenderPass();
};

Getting Started

Prerequisites

To build the project, you must first install the following tools:

• CMake 3.10 or higher
• Compiler environment with C++11 support

If you want to run the vulkan renderer, you need to install vulkan library as follows:

1. Download the Vulkan SDK from the official website: https://vulkan.lunarg.com/sdk/home
2. Install the SDK on your system. The installation process may vary depending on your operating system.
3. Set the environment variable VULKAN_SDK/VK_ICD_FILENAMES/VK_LAYER_PATH to the path where you installed the SDK.

Getting the Code

To get the code for this library, you can clone the GitHub repository using the following command:

git clone https://github.com/keith2018/SoftGLRender.git

Alternatively, you can download the source code as a ZIP file from the GitHub repository.

Building the Project

To build the project, navigate to the root directory of the repository and run the following commands:

mkdir build
cmake -B ./build -DCMAKE_BUILD_TYPE=Release
cmake --build ./build --config Release

This will generate the executable file and copy assets to directory bin, which you can run by executing the following command:

cd bin/Release
./SoftGLRender

Directory structure

• assets: GLTF models and skybox textures, assets.json is the index of all model & skybox materials
• src: Main source code directory
  • Base: Basic utility classes like file, hash, timer, etc.
  • Render: Renderer abstraction, include vertex, texture, uniform, framebuffer, etc.
    • Software: Software renderer implementation
    • OpenGL: OpenGL renderer implementation
    • Vulkan: Vulkan renderer implementation
  • Viewer: GLTF loading (based on Assimp), camera & controller, config panel, and render pass management
    • Shader/GLSL: GLSL shader code, for OpenGL & Vulkan renderer
    • Shader/Software: C++ simulation of vertex shaders and fragment shaders
• third_party: External libraries and assets

Third Party Libraries

• assimp https://github.com/assimp/assimp
• glfw https://github.com/glfw/glfw
• glm https://github.com/g-truc/glm
• glslang https://github.com/KhronosGroup/glslang
• imgui https://github.com/ocornut/imgui
• json11 https://github.com/dropbox/json11
• stb_image https://github.com/nothings/stb
• vma https://github.com/GPUOpen-LibrariesAndSDKs/VulkanMemoryAllocator

Contributing

If you would like to contribute to the project, you are welcome to submit pull requests with bug fixes, new features, or other improvements. Please ensure that your code is well-documented and adheres to the project's coding standards.

License

This code is licensed under the MIT License (see LICENSE).