pt: a golang path tracer

This is a CPU-only, unidirectional path tracing engine written in Go. It has lots of features and a simple API.

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Features

• Supports OBJ and STL
• Supports textures, bump maps and normal maps
• Supports raymarching of signed distance fields
• Supports volume rendering from image slices
• Supports various material properties
• Supports configurable depth of field
• Supports iterative rendering
• Uses k-d trees to accelerate ray intersection tests
• Uses all CPU cores in parallel
• 100% pure Go with no dependencies besides the standard library

Installation

go get -u github.com/fogleman/pt/pt

Examples

The are lots of examples to learn from! To try them, just run, e.g.

cd go/src/github.com/fogleman/pt
go run examples/gopher.go

Optional Embree Acceleration

You can optionally utilize Intel's Embree ray tracing kernels to accelerate triangle mesh intersections. First, install embree on your system: http://embree.github.io/ Then get the go-embree wrapper and checkout the embree branch of pt.

git checkout embree
go get -u github.com/fogleman/go-embree

Hello World

The following code demonstrates the basics of the API.

package main

import . "github.com/fogleman/pt/pt"

func main() {
	// create a scene
	scene := Scene{}

	// create a material
	material := DiffuseMaterial(White)

	// add the floor (a plane)
	plane := NewPlane(V(0, 0, 0), V(0, 0, 1), material)
	scene.Add(plane)

	// add the ball (a sphere)
	sphere := NewSphere(V(0, 0, 1), 1, material)
	scene.Add(sphere)

	// add a spherical light source
	light := NewSphere(V(0, 0, 5), 1, LightMaterial(White, 8))
	scene.Add(light)

	// position the camera
	camera := LookAt(V(3, 3, 3), V(0, 0, 0.5), V(0, 0, 1), 50)

	// render the scene with progressive refinement
	sampler := NewSampler(4, 4)
	IterativeRender("out%03d.png", 1000, &scene, &camera, sampler, 960, 540, -1)
}

Links

Here are some resources that I have found useful.

• WebGL Path Tracing - Evan Wallace
• Global Illumination in a Nutshell
• Simple Path Tracing - Iñigo Quilez
• Realistic Raytracing - Zack Waters
• Reflections and Refractions in Ray Tracing - Bram de Greve
• Better Sampling - Rory Driscoll
• Ray Tracing for Global Illumination - Nelson Max at UC Davis
• Physically Based Rendering - Matt Pharr, Greg Humphreys

Samples