raydiance

raydiance generates a path-traced PPM render from a JSON scene description.

Current Features

• Configurable camera
• Fixed lighting
• Spherical objects
• Lambertian, metal and dielectric materials
• Anti-aliasing
• Depth of field

Usage

raydiance -s <path to scene config file> [-o <output image name>]

A path to a scene configuration file is required, but the output image name is optional and defaults to img. Notably, the image name does not require a file extension, as the ppm extension is automatically appended during runtime.

Example

PPM Render (Converted to JPEG)

JSON Scene Description

{
  "lookFrom": {
    "x": -5.5,
    "y": 2.5,
    "z": 9.5
  },
  "lookAt": {
    "x": -4.0,
    "y": 1.0,
    "z": 0.0
  },
  "samplesPerPixel": 500,
  "maxDepth": 50,
  "imgWidth": 1200,
  "defocusAngle": 1.2,
  "focusDistance": 8.0,
  "fieldOfView": 60.0,
  "spheres": [
    {
      "centre": {
        "x": 0.0,
        "y": -1000.0,
        "z": -1.0
      },
      "radius": 1000.0,
      "material": {
        "type": "lambertian",
        "colour": {
          "r": 0.2,
          "g": 0.5,
          "b": 0.0
        }
      }
    },
    {
      "centre": {
        "x": -4,
        "y": 2.0,
        "z": -0.5
      },
      "radius": 2.0,
      "material": {
        "type": "lambertian",
        "colour": {
          "r": 0.2,
          "g": 0.2,
          "b": 0.8
        }
      }
    },
    {
      "centre": {
        "x": -8.0,
        "y": 1.5,
        "z": 0.0
      },
      "radius": 1.5,
      "material": {
        "type": "dielectric",
        "refIdx": 1.5
      }
    },
    {
      "centre": {
        "x": -8.0,
        "y": 1.5,
        "z": 0.0
      },
      "radius": -1.5,
      "material": {
        "type": "dielectric",
        "refIdx": 1.5
      }
    },
    {
      "centre": {
        "x": -3.0,
        "y": 1.25,
        "z": 5.0
      },
      "radius": 1.25,
      "material": {
        "type": "metal",
        "colour": {
          "r": 0.7,
          "g": 0.1,
          "b": 0.1
        },
        "fuzz": 0.2
      }
    },
    {
      "centre": {
        "x": -6.0,
        "y": 0.75,
        "z": 4.0
      },
      "radius": 0.75,
      "material": {
        "type": "metal",
        "colour": {
          "r": 0.7,
          "g": 0.6,
          "b": 0.5
        },
        "fuzz": 0.0
      }
    }
  ]
}

Configuration Options

• aspectRatio: The aspect ratio of the output image. It expects a double and the default value is 16.0 / 9.0.
• lookFrom: The position of the camera. It is an object with x, y, and z properties. Each property expects a double and the default values are x: 0.0, y: 0.0, z: 0.0.
• lookAt: The point the camera is looking at. It is an object with x, y, and z properties. Each property expects a double and the default values are x: 0.0, y: 0.0, z: 1.0.
• cameraUp: The up vector for the camera. It is an object with x, y, and z properties. Each property expects a double and the default values are x: 0.0, y: 1.0, z: 0.0.
• samplesPerPixel: The number of ray samples per pixel. It expects an integer and the default value is 10.
• maxDepth: The maximum number of bounces for a ray. It expects an integer and the default value is 10.
• imgWidth: The pixel width of the output image. It expects an integer and the default value is 400.
• defocusAngle: The defocus angle for the camera (higher value = greater bokeh). It expects a double and the default value is 0.0.
• focusDistance: The focus distance for the camera. It expects a double and the default value is 1.0.
• fieldOfView: The field of view for the camera. It expects a double and the default value is 45.0.
• spheres: An array of sphere objects in the scene. Each sphere object has the following properties:
  • centre: The centre of the sphere. It is an object with x, y, and z properties. Each property expects a double and there are no default values.
  • radius: The radius of the sphere. It expects a double and there are no default values.
  • material: The material of the sphere. It is an object with a type property, which is a string that can be "lambertian", "metal", or "dielectric". Depending on the type, it may also have other properties like colour (an object with r, g, and b properties, each a double) and refIdx or fuzz (both doubles). There are no default values for the material object.

Build Locally

Prerequisites

• C++17 compiler (tested with GCC and Clang)
• CMake 3.14+
• Clang-Format (optional)
• Clang-Tidy (optional)

Steps

1. Clone the project:

  git clone https://github.com/smercer10/raydiance.git

2. Navigate to the project directory:

  cd raydiance

3. Generate the build files:

  cmake -S . -B build

4. Build the project:

  cmake --build build

Running Tests

The project utilises the GoogleTest framework with CTest.

To execute the testcases, run the following command from the project root:

  cmake --build build --target test

Contributing

Contributions are always welcome!

See open issues for ways to get started.

Acknowledgements

The core ray tracing logic is based on the brilliant Ray Tracing in One Weekend Book Series.