README
¶
Izpi
A path tracer that started life as a Golang implementation of Peter Shirley's Raytracing books. It has since grown in scope and gained more features that were not part of the original version.
Requirements
- Go 1.26 or later
- For optimal BVH4 performance, build with
GOEXPERIMENT=simdto enable SIMD intrinsics
Goals
- Have fun.
- Learn about advanced computer graphics topics and put them to practice.
- Create a well-written and robust renderer that is usable with real world scene workloads.
- Integrate with DCC tools.
- Support professional VFX flows.
Non-goals
- Write the most performant path tracer possible.
- Build a GPU-based path tracer.
Roadmap
- Support for PBR materials.
- Distributed Rendering.
- Spectral Sampler to accurately simulate dispersion.
- Nested dielectrics.
- Physically correct light sources library.
- Firefly rejection.
- BVH traversal performance improvements.
- ACEScg workflow support.
- MaterialX support.
- OpenSubdiv support.
- OpenUSD support.
- Implement a Hydra render delegate.
- Adaptive sampling.
- Implement Bidirectional path tracing.
- Materials library.
- Water material.
- Sky simulation with day and night support.
- Scene conversion tool by implementing Go bindings for Open Asset Import Library.
- Implement Metropolis light transport.
Features
- Multi-threaded rendering engine.
- Compact scene format using Protocol Buffers.
- Automatic worker node discovery via Zeroconf, with Avahi integration on Linux and FreeBSD hosts.
- Network distributed system using gRPC and Protocol Buffers.
- Spectral rendering with support for dispersion and Beer-Lambert Law in dielectric materials.
- Full ACEScg workflow support.
- SoA BVH4 with Go 1.26 SIMD intrinsics (AVX2 on AMD64, optimized pure Go on ARM64) based on "An Efficient and Robust Ray–Box Intersection Algorithm" by Amy Williams, Steve Barrus, R. Keith Morley, and Peter Shirley and "Shallow Bounding Volume Hierarchies for Fast SIMD Ray Tracing of Incoherent Rays" by H. Dammertz, J. Hanika, and A. Keller.
- Phyisically correct light sources using SPDs from Michael Royer and the CIE Standard Illuminant F-Series.
- Rendering into a float64 image buffer.
- Direct, indirect and image-based lighting.
- Primitives: Spheres, boxes, rectangles and triangles.
- Wavefront OBJ import.
- Built-in materials: Glass, metal, Lambert, Perlin noise.
- Support for PBR flows with albedo, metalness, roughness, normal and displacement textures.
- Textures: PNG (LDR) and various HDR fromats (OpenEXR, HDR, PFM).
- Resulting images can saved in any format supported by OpenImageIO.
- Normal mapping.
- Displacement mapping through sub-texel mesh tessellation.
Gallery
The Stanford dragon
A demonstration of the effect of displacement mapping on a surface using Bricks078 from ambientCG.com, licensed under CC0 1.0 Universal.
A Cornell box showcasing various PBR materials from Free PBR.
A demonstration of the dispersion phenomenon calculated by the spectral sampler.
Directories
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| Path | Synopsis |
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cmd
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izpi
command
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texture_converter
command
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internal
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aabb
Package aabb implements functions to work with axis-aligned bounding boxes.
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Package aabb implements functions to work with axis-aligned bounding boxes. |
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camera
Package camera implements a set of functions to work with cameras.
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Package camera implements a set of functions to work with cameras. |
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colours
Package colours defines a few useful colours.
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Package colours defines a few useful colours. |
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displacement
Package displacement implements functions to apply displacement maps to triangles and meshes.
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Package displacement implements functions to apply displacement maps to triangles and meshes. |
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display
Package display implements an Fyne-backed preview window.
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Package display implements an Fyne-backed preview window. |
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grid
Package grid implements functions to walk a 2D grid using various algorithms.
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Package grid implements functions to walk a 2D grid using various algorithms. |
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hitable
Package hitable implements the methods used to compute intersections between a ray and geometry.
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Package hitable implements the methods used to compute intersections between a ray and geometry. |
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hitabletarget
Package hitabletarget implements the methods used to extract PDF data from hitables.
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Package hitabletarget implements the methods used to extract PDF data from hitables. |
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lightsources
Package lightsources implements different types of light sources.
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Package lightsources implements different types of light sources. |
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mat3
Package mat3 implements functions to work with 3x3 matrices.
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Package mat3 implements functions to work with 3x3 matrices. |
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material
Package material implements the different materials and their properties.
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Package material implements the different materials and their properties. |
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materials
Package materials implements a library of built-in spectral materials.
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Package materials implements a library of built-in spectral materials. |
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onb
Package onb implements methods to work with ortho-normal bases
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Package onb implements methods to work with ortho-normal bases |
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output
Package output implements the file output functionality.
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Package output implements the file output functionality. |
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pdf
Package pdf implements methods to work with probability density functions.
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Package pdf implements methods to work with probability density functions. |
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perlin
Package perlin implements functions to generate Perlin noise.
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Package perlin implements functions to generate Perlin noise. |
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postprocess
Package postprocess implements the postprocess pipeline.
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Package postprocess implements the postprocess pipeline. |
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ray
Package ray implements the interface and methods to work with rays.
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Package ray implements the interface and methods to work with rays. |
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render
Package render implements the main rendering loop.
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Package render implements the main rendering loop. |
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sampler
Package sampler implements different types of samplers.
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Package sampler implements different types of samplers. |
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scatterrecord
Package scatterrecord implements the scatter record.
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Package scatterrecord implements the scatter record. |
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scene
Package scene implements structures and methods to work with scenes.
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Package scene implements structures and methods to work with scenes. |
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scenes
Package scenes implements some sample scenes.
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Package scenes implements some sample scenes. |
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texture
Package texture implements different types of textures.
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Package texture implements different types of textures. |
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vec3
Package vec3 provides utility functions to work with vectors.
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Package vec3 provides utility functions to work with vectors. |
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wavefront
Package wavefront implements functions to parse Wavefront OBJ files and transform the data.
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Package wavefront implements functions to parse Wavefront OBJ files and transform the data. |
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