a Physically Based Renderer (PBR) in Go

pbr: a golang 3D renderer

Package pbr implements Physically-Based Rendering via a unidirectional CPU-only Monte Carlo path tracer.

pbr uses dep for dependency management.

$ go get github.com/hunterloftis/pbr
$ dep ensure
$ make

More examples

Hello, World

func main() {
	floor := surface.UnitCube(material.Plastic(1, 1, 1, 0.05))
	floor.Shift(geom.Vec{0, -0.1, 0}).Scale(geom.Vec{10, 0.1, 10})
	ball := surface.UnitSphere(material.Gold(0.05, 1))
	ball.Scale(geom.Vec{0.1, 0.1, 0.1})

	c := camera.NewSLR().MoveTo(geom.Vec{0, 0, -0.5}).LookAt(geom.Vec{0, 0, 0})
	s := surface.NewList(ball, floor)
	e := env.NewGradient(rgb.Black, rgb.Energy{750, 750, 750}, 7)

	scene := render.NewScene(c, s, e)
	err := render.Iterative(scene, "hello.png", 898, 450, 8, true)
	if err != nil {
		fmt.Fprintf(os.Stderr, "\nError: %v\n", err)
	}
}

Features

• Simple synchronous API, concurrent execution, 100% Go
• A standalone CLI
• .obj and .mtl meshes and materials (Wavefront)
• .hdri environment maps (Radiance)
• Physically-based materials (metalness/roughness workflow)
• Texture maps (base, roughness, metalness)
• Physically-based cameras (depth-of-field, f-stop, focal length, sensor size)
• Direct, indirect, and image-based lighting
• Progressive rendering

Related work

• https://github.com/alexflint/go-arg
• https://github.com/ftrvxmtrx/tga
• https://github.com/Opioid/rgbe
• https://github.com/fogleman/pt

CLI

Usage: pbr [--verbose] [--info] [--frames FRAMES] [--time TIME] [--material MATERIAL] [--width WIDTH] [--height HEIGHT] [--scale SCALE] [--rotate ROTATE] [--mark] [--out OUT] [--heat HEAT] [--profile] [--from FROM] [--to TO] [--focus FOCUS] [--lens LENS] [--fstop FSTOP] [--expose EXPOSE] [--bounce BOUNCE] [--indirect] [--ambient AMBIENT] [--env ENV] [--rad RAD] [--floor FLOOR] [--floorcolor FLOORCOLOR] [--floorrough FLOORROUGH] [--sun SUN] [--sunsize SUNSIZE] SCENE

Positional arguments:
  SCENE                  input scene .obj

Options:
  --verbose, -v          verbose output with scene information
  --info                 output scene information and exit
  --frames FRAMES, -f FRAMES
                         number of frames at which to exit [default: +Inf]
  --time TIME, -t TIME   time to run before exiting (seconds) [default: +Inf]
  --material MATERIAL    override material (glass, gold, mirror, plastic)
  --width WIDTH, -w WIDTH
                         rendering width in pixels [default: 800]
  --height HEIGHT, -h HEIGHT
                         rendering height in pixels [default: 450]
  --scale SCALE          scale the scene by this amount
  --rotate ROTATE        rotate the scene by this vector
  --mark                 render a watermark
  --out OUT, -o OUT      output render .png
  --heat HEAT            output heatmap as .png
  --profile              record performance into profile.pprof
  --from FROM            camera location
  --to TO                camera look point
  --focus FOCUS          camera focus ratio [default: 1]
  --lens LENS            camera focal length in mm [default: 50]
  --fstop FSTOP          camera f-stop [default: 4]
  --expose EXPOSE        exposure multiplier [default: 1]
  --bounce BOUNCE, -b BOUNCE
                         number of indirect light bounces [default: 6]
  --indirect             indirect lighting only (no direct shadow rays)
  --ambient AMBIENT      the ambient light color [default: &{1000 1000 1000}]
  --env ENV, -e ENV      environment as a panoramic hdr radiosity map (.hdr file)
  --rad RAD              exposure of the hdr (radiosity) environment map [default: 100]
  --floor FLOOR          size of the floor relative to the scene mesh
  --floorcolor FLOORCOLOR
                         the color of the floor [default: &{0.9 0.9 0.9}]
  --floorrough FLOORROUGH
                         roughness of the floor [default: 0.5]
  --sun SUN              position of a daylight emitter
  --sunsize SUNSIZE      size of the sun [default: 1]
  --help, -h             display this help and exit
  --version              display version and exit

Renders

All of these, and many more are in the Makefile. To render them yourself, you’ll need the fixtures directory of 3D assets:

$ make fixtures

Note: the download is over a gigabyte!

Render Farm

The farm package provides a client and server for quickly spinning up a render farm. The client workers render a scene and POST samples to the server over HTTP. The server integrates the samples into a render which it returns at GET /.

To try out the ‘toys’ render farm example:

$ heroku create
$ heroku stack:set container
$ heroku labs:enable runtime-dyno-metadata
$ git push heroku master
$ heroku scale web=1:performance-l worker=10:performance-l
$ heroku open