README.md

Yet Another Raytracer

This is a raytracer written in 2.3k lines of C++.

Supported features:

• Algorithm

  1. Path tracing
  2. Stochastic progressive photon mapping (SPPM)

• Model

  1. Triangle, plane, sphere
  2. Bézier curve rotating around an axis (solved by Newton's method or triangulation)
  3. Triangle mesh (imported from .obj file)

• Material

  1. Lambert reflectance
  2. Speculative material
  3. Reflective and semi-reflective material
  4. Refractive material. Reflection rate calculated by Fresnel-Schlick formula

• Additional features

  1. Texture u-v mapping for mesh, plane, sphere and Bezier surface
  2. Normal texture for some objects
  3. Normal interpolation based on barycentric coordinates
  4. Soft shadow produced by light source sampling
  5. Super-sampling for anti-aliasing
  6. Depth of field
  7. Motion Blur
  8. Intersection finding accelerated by AABB and BVH data structure
  9. OpenMP multi-threading

You may refer to GitHub Release page for a more detailed report (in Chinese).

Gallery

1. Reflective and refractive balls:

./build/RT -i scenes/cornell-2ball.yml -o output/final/cornell-2ball.bmp -p4 -s1024

2. Bezier curve:

./build/RT -i scenes/cornell-bezier.yml -o output/final/cornell-bezier.bmp -p4 -s512

3. Reflective and refractive balls (SPPM version)

./build/RT_sppm -i scenes/cornell-2ball.yml -o output/final/cornell-2ball-sppm.bmp -p 10000000 -n 50 -r 0.008

4. Color bleeding with path tracing

./build/RT -i scenes/bleeding.yml -o output/final/bleeding.bmp -p4 -s512

5. Depth of field

./build/RT -i scenes/cornell-depth.yml -o output/final/cornell-depth.bmp -p4 -s1024

6. Motion Blur

./build/RT -i scenes/motion.yml -o output/final/motion.bmp -p3 -s512

6. Dragon (100k triangles)

./build/RT -i scenes/dragon.yml -o output/final/dragon.bmp -p4 -s512

7. M4A1 (100k triangles)

./build/RT -i scenes/m4a1.yml -o output/final/m4a1.bmp -p4 -s512

8. Caustic dragon with SPPM

./build/RT_sppm -i scenes/caustics.yml -o output/final/caustics.bmp -p 10000000 -n 50 -r 0.008

File Hierarchy

.
├── .gitignore                        # exclude some annoying files from git
├── assets                            # .obj, .mtl and textures, not included in this repo
├── CMakeLists.txt                    # yes, this project builds with CMake
├── LICENSE                           # GPL3 licence, use with care
├── Makefile                          # simply a script wrapper
├── README.md                         # what you are reading now
├── deps
│     └── vecmath                     # a tiny library for vector/matrix operation
├── results                           # output images (png and bmp)
├── scenes                            # scene description file stored in yaml
├── src                               # source code for our ray tracer
│     ├── core
│     │     ├── camera.cpp
│     │     ├── camera.h              # perspective camera with depth of field
│     │     ├── hit.cpp
│     │     ├── hit.h                 # light hit the object
│     │     ├── light.cpp
│     │     ├── light.h               # light sources emit rays
│     │     ├── material.cpp
│     │     ├── material.h            # providing a few kind of materials
│     │     ├── ray.cpp
│     │     ├── ray.h                 # emitted from camera, or from light source
│     │     ├── texture.cpp
│     │     └── texture.h             # uv mapping of texture
│     ├── objects
│     │     ├── bvh.cpp
│     │     ├── bvh.h                 # implementing BVH algorithm
│     │     ├── group.cpp
│     │     ├── group.h               # a collection of objects
│     │     ├── mesh.cpp
│     │     ├── mesh.h                # triangular mesh, powered by BVH
│     │     ├── obj_import.cpp
│     │     ├── obj_import.h          # import mesh from obj file
│     │     ├── object3d.h            # abstract base class of all objects
│     │     ├── plane.cpp
│     │     ├── plane.h               # infinite size plane
│     │     ├── rotate_bezier.cpp     # bezier curve rotating around an axis
│     │     ├── rotate_bezier.h
│     │     ├── sphere.cpp
│     │     ├── sphere.h              # sphere
│     │     ├── triangle.cpp
│     │     └── triangle.h            # triangle, supporting normal interpolation
│     ├── renderers
│     │     ├── path_tracing.cpp
│     │     ├── path_tracing.h        # implementing path tracing
│     │     ├── photon_mapping.cpp
│     │     └── photon_mapping.h      # implementing SPPM
│     ├── pt_main.cpp                 # main file for path tracing
│     ├── sppm_main.cpp               # main file for SPPM
│     └── utils
│         ├── aabb.cpp
│         ├── aabb.h                  # axis-aligned bounding box
│         ├── ball_finder.hpp         # a simple data structure to find spheres containing a point
│         ├── debug.h                 # some debugging/logging stuff
│         ├── image.cpp
│         ├── image.h                 # write image to file
│         ├── math_util.cpp
│         ├── math_util.h             # random number generator, and some misc math functions
│         ├── prog_bar.hpp            # showing progress bar for long-time rendering
│         ├── scene_parser.cpp
│         └── scene_parser.h          # parse scene from yaml file
└── tests                             # additional correctness tests
    ├── ball_finder_test.cpp
    └── bezier_intersection_test.cpp

Compilation

Prerequisite:

1. CMake no older than 3.14
2. C++ compiler supporting C++17 and OpenMP
3. Network connection to GitHub (for automatic dependency fetching)

After cloning the repository:

cmake -G Ninja -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

Add -DRT_BUILD_TEST if you want tests.

The compiled binary files RT and RT_sppm lie in ./build. Both binarys requires a few command line arguments. Run with --help to find out.

External Dependencies

1. glog: logging
2. fmt: string interpolation
3. tinyobjloader: Wavefront .obj file parser
4. args: command line argument parser
5. yaml-cpp: yaml parser because we store the scene in a yaml file
6. lodepng: PNG encoder/decoder for reading PNG texture
7. googletest: tester