Merge BVH branch

Cargo.toml

@@ -3,9 +3,6 @@ name = "weekend_of_rays"
 version = "0.1.0"
 edition = "2024"
 
-[profile.release]
-debug = true
-
 [dependencies]
 chrono = "0.4.41"
 fastrand = "2.3.0"

README.md

@@ -0,0 +1,82 @@
+# Softpasses
+
+Physically based software pathtracer
+
+## Current features
+
+- Support for multiple types of primitives (Spheres, Triangles, Parallelograms, Parallelipeds)
+- Handrolled BVH2 implementation (SAH construction, ordered traversal)
+- Triangle mesh loading (.obj format)
+- Materials: Lambertian diffuse BRDF, basic glass BSDF and metallic BRDF
+- Environment map defined lighting (.hdr, .exr)
+- Thin lens camera model with DOF simulation
+- Generation of auxiliary passes (albedo, normal) for denoising
+- Generation of BVH debug and visualization passes (node intersects, primitive checks)
+- Multithreaded, tiled rendering
+- Denoising through Intel OpenImageDenoise integration
+- Basic filmic tonemapping
+
+## Renders
+
+All images were rendered and postprocessed exclusively within this software on an i7U quadcore @ 3.1 GHz processor.
+
+1080p, 512 spp, ~870k triangles @ ~1 MRays/s in 17:45 minutes
+![Final render of the Stanford dragon with environment map lighting and DoF simulation](renders/stanford_dragon_full_001/beauty_tonemapped.png)
+
+1080p, 1024 spp, ~5k primitives @ ~0.7 MRays/s in 49:40 minutes (no denoising/tonemapping)
+![Render of Stanford bunny without denoising or tonemapping](renders/stanford_bunny_shelf_001/color.png)
+
+### Auxiliary and Intermediate passes
+In addition to the final render, Softpasses also produces and outputs a collection of auxiliary/intermediate passes.
+
+#### Color pass
+The raw computed HDR luminance data before denoising, tonemapping and gamma correction.
+![Linear HDR data of the Stanford dragon render](renders/stanford_dragon_full_001/color.png)
+
+#### Albedo and Normal passes
+ Describing the diffuse reflection and surface normal properties of the scene, they serve as common auxiliary inputs for denoisers, and are fed to the Intel OIDN library during the postprocessing stage.
+![Albedo data of the Stanford dragon scene](renders/stanford_dragon_full_001/albedo.png)
+![Surface normal data of the Stanford dragon scene](renders/stanford_dragon_full_001/normal.png)
+
+#### BVH visualization
+BVH visualization passes such as **Average number of node checks per pixel** and **Average number of primitive checks per pixel** aid in profiling and debugging the acceleration structure. Both heatmapped (ie normalized to 0-1, as seen below) and raw HDR versions are supplied.
+![Average number of node AABB checks / pixel in the Stanford dragon scene](renders/stanford_dragon_full_001/aabb_checks_heatmapped.png)
+![Average number of primitve checks / pixel in the Stanford dragon scene](renders/stanford_dragon_full_001/primitive_checks_heatmapped.png)
+
+
+## Planned features
+
+- Environment map importance sampling
+	(Contrast-rich environment maps lead to very noisy images currently. Ideally take advantage of MIS to importance sample both the environment map and materials.)
+- Support for texture mapping on models (eg diffuse, roughness, metallic maps)
+- Implementation of a physically based general-purpose BSDF, eg the Burley BSDF
+- Support for a user friendly scene description format, like glTF or USD
+
+## Building and Usage
+
+Prerequisites: 
+ - Have [Intel OpenImageDenoise](https://github.com/RenderKit/oidn) library installed
+
+Then build in release mode (debug builds are *very* slow):  
+```cargo build --release```
+
+Run the following to render the current scene:  
+```cargo run --release -- <output directory>```
+
+There is no proper, user friendly way to do so at the moment, but you can play around with the scene and render settings inside `main`. 
+
+## References 
+
+A practical introduction to the basics of raytracing, which this project was originally loosely based on:  
+[Peter Shirley - Ray Tracing in One Weekend](https://raytracing.github.io/books/RayTracingInOneWeekend.html)
+
+For all your PBR needs:  
+[Pharr, Jakob, Humphreys - Physically Based Rendering: From Theory to Implementation](https://www.pbrt.org/)
+
+A great tutorial on building BVHs:  
+[Bikker - How to Build a BVH (Article series)](https://jacco.ompf2.com/2022/04/13/how-to-build-a-bvh-part-1-basics/)
+
+Arguably more of historical importance, these two papers were among the first to discuss the usage of BVHs in Raytracing. Regardless, they give a good overview of the fundamental problem at hand:  
+[Kay, Kajiya (1986) - Ray Tracing Complex Scenes](https://papers.cumincad.org/data/works/att/67d2.content.pdf?utm_source=chatgpt.com)   
+[Goldsmith, Salmon (1987) - Automatic Creation of Object Hierarchies for Ray Tracing](https://doi.org/10.1109/MCG.1987.276983)
+

assets/models/cube.obj

@@ -0,0 +1,24 @@
+# Blender 4.5.3 LTS
+# www.blender.org
+o Cube
+v 0.500000 1.000000 -0.500000
+v 0.500000 0.000000 -0.500000
+v 0.500000 1.000000 0.500000
+v 0.500000 0.000000 0.500000
+v -0.500000 1.000000 -0.500000
+v -0.500000 0.000000 -0.500000
+v -0.500000 1.000000 0.500000
+v -0.500000 0.000000 0.500000
+vn -0.0000 1.0000 -0.0000
+vn -0.0000 -0.0000 1.0000
+vn -1.0000 -0.0000 -0.0000
+vn -0.0000 -1.0000 -0.0000
+vn 1.0000 -0.0000 -0.0000
+vn -0.0000 -0.0000 -1.0000
+s 0
+f 1//1 5//1 7//1 3//1
+f 4//2 3//2 7//2 8//2
+f 8//3 7//3 5//3 6//3
+f 6//4 2//4 4//4 8//4
+f 2//5 1//5 3//5 4//5
+f 6//6 5//6 1//6 2//6