Raytracer

A raytracer written in Go, which renders JSON files into an image. I wrote this to learn more about raytracing, and to try out Go on something other than server-side programming.

Features

• Renders large/complicated scenes quickly using goroutines. Supports orthographic, simple perspective and fisheye projections.

• Currently only supports materials, not rendering textures or UV mapping. Additionally, only planes, triangles, spheres and boxes are supported. Support for UV mapping and more complex/custom shapes may be added eventually.

• Both Lambertian and Phong lighting models are supported, and both work with reflections and shadows. Refraction is not currently available.

• Configurable anti-aliasing through super sampling.

Installing

Requires Go to be installed and setup. If it is not, refer to golang.org/doc/install to get started.

Run go get -u github.com/brendanburkhart/raytracer/... to install or update.

Usage

    raytracing.exe <folder or JSON file>...

Run the executable with the data file(s) and/or folder(s) containing the scenes to be rendered. Each scene will be rendered and output into a PNG of the same name as the scene's data file in the same location. Example: raytracing.exe ./scenes/example.json.

Scene data description

Scenes are described using JSON files in the following format:

{
  "width": Output image width,
  "height": Output image height,
  "camera": {
    "position": Vector, specifies camera origin,
    "target": Vector, specifies where the camera is pointed,
    "roll": Camera roll in degrees, positive is counter-clockwise when facing the same direction as the camera,

    "antiAliasingFactor": Super samples per pixel, must be at least 1. Optional, default is 1,
    "lightingModel": One of "lambertian", or "phong". Optional, default is "phong",

    "projection": Projection type - one of "perspective", "orthographic", or "fisheye",

    "viewWidth": If using an orthographic projection, viewWidth must be specified. It is the view width of the rendered image in in-scene units. Can be used with a perspective projection, in which case focalLength must be specified.
    "hfov": If using a fisheye projection, hfov must be specified. It is the horizontal field of view in degrees. Can optionally replace viewWidth for a perspective projection.
    "focalLength": For perspective projection, distances from origin to render-plane. If this is not specified, opticalRadius must be.
    "opticalRadius": Radius of circle around camera origin in which render-plane is fit as plane with angle matching hfov.
  },
  "scene": {
    "materials": [Materials],
    "lights": [Lights],
    "objects": [Object primitives]
  }
}

Vectors are specified as {"x": x, "y": y, "z": z}. Colors are specified as {"red": 0.0-1.0, "green": 0.0-1.0, "blue": 0.0-1.0}.

Materials are specified as:

{
    "specular": Specular color,
    "diffuse": Diffuse color,
    "ambient": Ambient color,
    "alpha": 0 or greater, higher values create brighter, smaller specular highlights,
    "reflectance": 0.0 or greater, percentage of light reflected by material
},

Lights are specified as:

{
    "position": Vector,
    "specular": Specular component, color,
    "diffuse": Diffuse component, color,
    "ambient": Ambient component, color
}

Object in the scene can be one of three primitives: sphere, box or plane.

Sphere:

{
    "type": "sphere",
    "center": Position vector,
    "radius": Radius of sphere,
    "material": Index of material within array of materials
}

Box:

{
    "type": "box",
    "minCorner": Position vector of minimum corner,
    "maxCorner": Position vector of maximum corner,
    "material": Index of material within array of materials
},

Plane:

{
    "type": "plane",
    "point": Position vector of any point in plane,
    "normal": Normal vector of plane,
    "material": Index of material within array of materials
},