GoTracer

A Go implementation of Ray Tracing in One Weekend by Peter Shirley.

Features:

• Provides a library and executable to trace a bunch of spheres with Matte, Metal and transparent surfaces.
• Provides a framework to ray trace a bunch or spheres on a distributed systems controlled by master/agent configuration

Usages

Prepare rendering spec as per Tracing Specification

Basic

go get github.com/DheerendraRathor/GoTracer

goTracer --spec=/path/to/spec.json

On distributed Systems

1. Install and run ray tracing agent on all machines

go get github.com/DheerendraRathor/GoTracer/net/agent

# Provide an addr where agent will listen. Address (including port) must be visible to master
agent --addr=0.0.0.0:1233

2. Prepare agents.json file with list of all agents

[
  "localhost:9190",
  "localhost:9191",
  "localhost:9192"
]

3. Install and run master

go get github.com/DheerendraRathor/GoTracer/net/master

master --spec=/path/to/spec.json --agents=/path/to/agents.json

4. Sit back and relax while image is being rendered :)

As library

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"

	"github.com/DheerendraRathor/GoTracer/models"
	"github.com/DheerendraRathor/GoTracer/tracer"
)

func main() {

	file, e := ioutil.ReadFile("mySpecFile.json")
	if e != nil {
		panic(fmt.Sprintf("File error: %v\n", e))
	}

	var env models.World
	json.Unmarshal(file, &env)

	/*
		This channel is used to track progress of ray tracing. If env.Settings.ShowProgress is set to true.
		On each pixel traced a `false` value is pushed to progress channel. And once all pixel are processed a `true` value is pushed into channel.

		It is responsibility of caller to create sufficiently large buffered channel and read it responsibly if env.Settings.ShowProgress is true.
		Otherwise program might hang.
	*/
	progress := make(chan *models.Pixel, 100)
	closeChan := make(chan bool)
	defer close(progress)

	go goTracer.GoTrace(&env, progress, closeChan)

	go func() {
		for pixel := range progress {
			if pixel == nil {
				// Rendering complete
				return
			}
			// Do processing with pixel here.
			// Want to generate JPEG? GIF? Real time rendering on UI? Show weird looking progress bar? Your call. You've the pixels now
		}
	}()

	// To stop rendering in middle, just pass a value to closeChan.
	// GoTracer does a non-blocking check on closeChan before rendering a pixel. If channel has a value, it will stop rendering and send nil to
	// progress channel.
	// Caveat: Existing goroutines for other pixel will continue to run.

}

Tracing Specification

This program takes a JSON specification of environment to be traced. Currently only spheres are supported.

{
  "Settings": {
    "ShowProgress": true,
    "RenderRoutines": -1,
    "RenderDepth": 10
  },
  "Image": {
    "OutputFile": "./out/renderedImage.png",
    "Width": 400,
    "Height": 200,
    "Samples": 10,
    "Patch": [0, 200, 0, 400]
  },
  "Camera": {
    "LookFrom": [-2, 1, 0.5],
    "LookAt": [0, 0, -1],
    "UpVector": [0, 1, 0],
    "FieldOfView": 45,
    "AspectRatio": 2,
    "Focus": 2.69,
    "Aperture": 0.04
  },
  "Objects": {
    "Spheres": [
      {
        "Center": [0, 0, -1],
        "Radius": 0.5,
        "Surface": {
          "Type": "Lambertian",
          "Albedo": [0.8, 0.1, 0.1],
          "Fuzz": 0.1,
          "RefIndex": 1.3
        }
      }
    ]
  }
}

Field		type	Details
Settings	ShowProgress	boolean	Show a progress bar while Image is being rendered
	RenderRoutines	integer	Number of goroutines for ray tracing. If value is less than zero then runtime.NumCPU() is taken
	RenderDepth	integer	Number of recursion for a ray after hitting an object
Image	OutputFile	string	Path of file where rendered image should be saved. Rendered image is PNG
	Width	integer	Width of Rendered Image
	Height	integer	Height of Rendered Image
	Samples	integer	Number of samples per pixel
	Patch	list[int][4]	Defines specific patch of image to be rendered. Patch is defined as [x0, y0, x1, y1] and all points (x, y) are considered given that x0 ≤ x < x1 and y0 ≤ y < y1
Camera	LookFrom	list[float][3]	Coordinates of camera lens
	LookAt	list[float][3]	Coordinate of point where camera is pointed.
	UpVector	list[float][3]	Point defining direction of up direction for camera
	FieldOfView	float	Camera field of views in degrees
	AspectRatio	float	Ratio of height and width of camera image plane
	Focus	float	Focal length of camera. This and Aperture are used for creation of depth of field effect
	Aperture	float	Camera aperture diameter
Objects	Spheres	List[Sphere]	List of spheres in world to be rendered
Sphere	Center	list[float][3]	Center of sphere
	Radius	float	Radius of sphere
	Surface	Material	Material description of Sphere
Material	Type	string	Type of Material. Must be from Lambertian, Metal, Dielectric
	Albedo	list[float][3]	Albedo of Material
	Fuzz	float	Fuzziness in reflection for Metal surfaces. Should be in range [0.0, 1)
	RefIndex	float	Refractive index for Dielectric surfaces.

Note: list[x][n] => list of elements of type x with size n