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Wrap sampling logic/tracking in a struct.

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This commit is contained in:
Nathan Vegdahl 2022-08-04 11:11:25 -07:00
parent 1f7c412e25
commit a12de4c3d7
8 changed files with 218 additions and 87 deletions
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5
Cargo.lock generated
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@ -352,6 +352,7 @@ dependencies = [
"openexr",
"png_encode_mini",
"rmath",
"rrand",
"rustc-serialize",
"scoped_threadpool",
"sobol_burley",
@ -565,6 +566,10 @@ dependencies = [
"rand 0.6.5",
]
[[package]]
name = "rrand"
version = "0.1.0"
[[package]]
name = "rustc-serialize"
version = "0.3.24"

6
Cargo.toml
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@ -5,6 +5,7 @@ members = [
"sub_crates/compact",
"sub_crates/halton",
"sub_crates/rmath",
"sub_crates/rrand",
"sub_crates/spectral_upsampling",
]
@ -48,12 +49,15 @@ path = "sub_crates/color"
[dependencies.compact]
path = "sub_crates/compact"
[dependencies.halton]
[dependencies.halton]
path = "sub_crates/halton"
[dependencies.rmath]
path = "sub_crates/rmath"
[dependencies.rrand]
path = "sub_crates/rrand"
[dependencies.spectral_upsampling]
path = "sub_crates/spectral_upsampling"

9
src/algorithm.rs
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@ -5,10 +5,9 @@ use std::{
mem::MaybeUninit,
};
use crate::{
hash::hash_u64,
lerp::{lerp_slice, Lerp},
};
use rrand::mix_seed_u64;
use crate::lerp::{lerp_slice, Lerp};
/// Selects an item from a slice based on a weighting function and a
/// number (n) between 0.0 and 1.0. Returns the index of the selected
@ -209,7 +208,7 @@ where
let mut seed = n as u64;
loop {
let i = left + (hash_u64(right as u64, seed) as usize % (right - left));
let i = left + (mix_seed_u64(right as u64, seed) as usize % (right - left));
slc.swap(i, right - 1);
let ii = left + {

45
src/hash.rs
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@ -1,45 +0,0 @@
/// A fast seedable 32-bit hash function.
pub fn hash_u32(mut n: u32, seed: u32) -> u32 {
// We rotate the bits of `seed` so it's unlikely to interact with `n`
// in bad ways if they're both e.g. incrementing. The particular
// rotation constant used here isn't special.
n ^= seed.rotate_left(23);
// From https://github.com/skeeto/hash-prospector
n ^= n >> 16;
n = n.wrapping_mul(0x21f0aaad);
n ^= n >> 15;
n = n.wrapping_mul(0xd35a2d97);
n ^= n >> 15;
// Xor by a random number so input zero doesn't map to output zero.
// The particular number used here isn't special.
n ^ 0xe6fe3beb
}
/// A fast seedable 64-bit hash function.
pub fn hash_u64(mut n: u64, seed: u64) -> u64 {
// We rotate the bits of `seed` so it's unlikely to interact with `n`
// in bad ways if they're both e.g. incrementing. The particular
// rotation constant used here isn't special.
n ^= seed.rotate_left(47);
// From https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
n ^= n >> 30;
n = n.wrapping_mul(0xbf58476d1ce4e5b9);
n ^= n >> 27;
n = n.wrapping_mul(0x94d049bb133111eb);
n ^= n >> 31;
// Xor by a random number so input zero doesn't map to output zero.
// The particular number used here isn't special.
n ^ 0x4acc3f27cc712c9d
}
/// Returns a random float in [0, 1] based on 'n' and a seed.
/// Generally use n for getting a bunch of different random
/// numbers, and use seed to vary between runs.
pub fn hash_u32_to_f32(n: u32, seed: u32) -> f32 {
const INV_MAX: f32 = 1.0 / std::u32::MAX as f32;
hash_u32(n, seed) as f32 * INV_MAX
}

1
src/main.rs
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@ -22,7 +22,6 @@ mod boundable;
mod camera;
mod color;
mod fp_utils;
mod hash;
mod image;
mod lerp;
mod light;

106
src/renderer.rs
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@ -234,13 +234,16 @@ impl<'a> Renderer<'a> {
// the samplers themselves.
let si_offset =
owen4(morton::encode(x, y), self.seed).wrapping_mul(self.spp as u32);
for si in 0..self.spp {
let si = (si as u32).wrapping_add(si_offset);
for si in 0..(self.spp as u32) {
let mut sample_gen = SampleGen::new(si_offset + si, self.seed);
// Raw sample numbers.
let d0 = golden_ratio_sample(si);
let (d1, d2, d3, d4) = get_sample_4d(si, 0, self.seed);
let (d5, _, _, _) = get_sample_4d(si, 1, self.seed);
let d0 = golden_ratio_sample(si.wrapping_add(si_offset));
let [d1, d2, d3, _] = sample_gen.next_dims();
sample_gen.inc_padding();
let [d4, d5, _, _] = sample_gen.next_dims();
sample_gen.inc_padding();
// Calculate the values we need to generate a camera ray.
let (img_x, img_y) = {
@ -260,7 +263,7 @@ impl<'a> Renderer<'a> {
.camera
.generate_ray(img_x, img_y, time, wavelength, lens_uv.0, lens_uv.1);
let path_col =
trace_camera_light_path(&mut tracer, &self.scene, ray, si, self.seed);
trace_camera_light_path(&mut sample_gen, &mut tracer, &self.scene, ray);
// Accummulate light path color to pixel.
let mut col = img_bucket.get(x, y);
@ -322,11 +325,10 @@ impl<'a> Renderer<'a> {
}
fn trace_camera_light_path(
sample_gen: &mut SampleGen,
tracer: &mut Tracer,
scene: &Scene,
camera_ray: Ray,
sample_index: u32,
seed: u32,
) -> SpectralSample {
use crate::shading::surface_closure::SurfaceClosure;
use crate::surface::SurfaceIntersection;
@ -337,7 +339,6 @@ fn trace_camera_light_path(
let mut ray_pdf = 1.0; // PDF from generating the camera/bounce ray.
let mut acc_color = Float4::splat(0.0); // Accumulated color.
let mut attenuation = Float4::splat(1.0); // Color attenuation along the path so far.
let mut sampling_seed = seed + 1;
for bounce in 0..BOUNCE_COUNT {
let isect = tracer.trace(ray);
@ -370,8 +371,8 @@ fn trace_camera_light_path(
//-------------------------------------------------
// Sample light sources.
sampling_seed = sampling_seed.wrapping_add(1);
let (light_n, d2, d3, d4) = get_sample_4d(sample_index, 0, sampling_seed);
sample_gen.inc_padding();
let [light_n, d2, d3, d4] = sample_gen.next_dims();
let light_uvw = (d2, d3, d4);
let light_info = scene.sample_lights(
@ -455,8 +456,8 @@ fn trace_camera_light_path(
// Sample closure
let (dir, filter, pdf) = {
sampling_seed = sampling_seed.wrapping_add(1);
let (u, v, _, _) = get_sample_4d(sample_index, 0, sampling_seed);
sample_gen.inc_padding();
let [u, v, _, _] = sample_gen.next_dims();
closure.sample(
idata.incoming,
@ -509,28 +510,67 @@ fn trace_camera_light_path(
SpectralSample::from_parts(acc_color, ray.wavelength)
}
/// Gets a sample, using LDS samples for lower dimensions,
/// and switching to random samples at higher dimensions where
/// LDS samples aren't available.
#[inline(always)]
fn get_sample_4d(i: u32, dimension_set: u32, seed: u32) -> (f32, f32, f32, f32) {
match dimension_set {
ds if ds < sobol_burley::NUM_DIMENSION_SETS_4D as u32 => {
// Sobol sampling.
//
let n4 = sobol_burley::sample_4d(i, ds, seed);
(n4[0], n4[1], n4[2], n4[3])
/// Generates Owen-scrambled, padded Sobol samples.
#[derive(Debug, Copy, Clone)]
struct SampleGen {
padding_rng: rrand::Rng,
dimension_rng: rrand::Rng,
padding_seed: u32,
sample_i: u32,
sample_i_shuffled_rev: u32,
dimension_i: u32,
}
ds => {
// Random sampling.
use crate::hash::hash_u32_to_f32;
(
hash_u32_to_f32((ds * 4 + 0) ^ (i << 16), seed),
hash_u32_to_f32((ds * 4 + 1) ^ (i << 16), seed),
hash_u32_to_f32((ds * 4 + 2) ^ (i << 16), seed),
hash_u32_to_f32((ds * 4 + 3) ^ (i << 16), seed),
impl SampleGen {
pub fn new(sample_i: u32, seed: u32) -> Self {
let mut gen = Self {
sample_i: sample_i,
sample_i_shuffled_rev: 0,
padding_seed: 0,
dimension_i: 0,
padding_rng: rrand::Rng::new(rrand::mix_u64(seed as u64)),
dimension_rng: rrand::Rng::new(0),
};
gen.inc_padding();
gen
}
/// Increments the padding.
pub fn inc_padding(&mut self) {
use sobol_burley::parts::owen_scramble_rev;
self.padding_seed = self.padding_rng.u32();
self.sample_i_shuffled_rev =
owen_scramble_rev(self.sample_i.reverse_bits(), self.padding_seed);
self.dimension_rng = rrand::Rng::new(self.padding_rng.u64());
self.dimension_i = 0;
}
/// Gets the next four dimensions of the current sample.
pub fn next_dims(&mut self) -> [f32; 4] {
use sobol_burley::parts::{owen_scramble_int4_rev, sobol_4d_rev};
let sobol_int_rev = sobol_4d_rev(self.sample_i_shuffled_rev, self.dimension_i);
self.dimension_i += 1;
let rand1 = self.dimension_rng.u64();
let rand2 = self.dimension_rng.u64();
let sobol_owen_int = owen_scramble_int4_rev(
sobol_int_rev,
[
rand1 as u32,
(rand1 >> 32) as u32,
rand2 as u32,
(rand2 >> 32) as u32,
]
.into(),
)
}
.reverse_bits();
sobol_owen_int.to_f32_norm()
}
}

8
sub_crates/rrand/Cargo.toml Normal file
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@ -0,0 +1,8 @@
[package]
name = "rrand"
version = "0.1.0"
edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]

121
sub_crates/rrand/src/lib.rs Normal file
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@ -0,0 +1,121 @@
//! Sources of deterministic "randomness" for rendering applications.
/// Convert a `u32` to a float in [0.0, 1.0).
///
/// Use for getting f32 values from random u32 sources.
///
/// Note: this is a linear mapping from [0, int_max] to [0.0, 1.0).
#[inline(always)]
pub fn u32_to_f32_norm(n: u32) -> f32 {
f32::from_bits((n >> 9) | 0x3f800000) - 1.0
}
//-------------------------------------------------------------
/// A fast RNG.
///
#[derive(Debug, Copy, Clone)]
pub struct Rng {
state: u64,
}
impl Rng {
/// Creates a new Rng from a seed.
///
/// A seed of zero is perfectly fine, and does not affect the quality
/// of the generator.
#[inline]
pub fn new(seed: u64) -> Self {
Self { state: seed }
}
/// Gets the nth relative RNG stream from this one.
///
/// The returned stream will be at the same point in its sequence as
/// this one.
#[inline]
pub fn nth_stream(&self, n: u64) -> Self {
Self {
// We just jump forward 2^40*n states. This gives us 2^24
// unique streams, each of which is 2^40 numbers long.
state: self
.state
.wrapping_add(0xa0761d6478bd642f_u64.wrapping_mul(1 << 40).wrapping_mul(n)),
}
}
/// Returns a random u32 in [0, int_max].
#[inline(always)]
pub fn u32(&mut self) -> u32 {
self.u64() as u32
}
/// Returns a random u64 in [0, int_max].
#[inline(always)]
pub fn u64(&mut self) -> u64 {
// The wyrand RNG.
self.state = self.state.wrapping_add(0xa0761d6478bd642f);
let t = (self.state as u128).wrapping_mul(self.state as u128 ^ 0xe7037ed1a0b428db);
((t >> 64) ^ t) as u64
}
}
//-------------------------------------------------------------
/// A fast 32-bit mixing function.
///
/// Scrambles the input number to produce a different deterministic
/// "random" number.
#[inline(always)]
pub fn mix_u32(mut n: u32) -> u32 {
// From https://github.com/skeeto/hash-prospector
n ^= n >> 16;
n = n.wrapping_mul(0x21f0aaad);
n ^= n >> 15;
n = n.wrapping_mul(0xd35a2d97);
n ^= n >> 15;
// Xor by a random number so input zero doesn't map to output zero.
// The particular number used here isn't special.
n ^ 0xe6fe3beb
}
/// A fast seedable 32-bit mixing function.
///
/// Same as `mix_u32()` but takes a seed.
#[inline(always)]
pub fn mix_seed_u32(n: u32, seed: u32) -> u32 {
// We rotate the bits of `seed` so it's unlikely to interact with `n`
// in bad ways if they're both e.g. incrementing. The particular
// rotation constant used here isn't special.
mix_u32(n ^ seed.rotate_left(23))
}
/// A fast 64-bit mixing function.
///
/// Scrambles the input number to produce a different deterministic
/// "random" number.
#[inline(always)]
pub fn mix_u64(mut n: u64) -> u64 {
// From https://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
n ^= n >> 30;
n = n.wrapping_mul(0xbf58476d1ce4e5b9);
n ^= n >> 27;
n = n.wrapping_mul(0x94d049bb133111eb);
n ^= n >> 31;
// Xor by a random number so input zero doesn't map to output zero.
// The particular number used here isn't special.
n ^ 0x4acc3f27cc712c9d
}
/// A fast seedable 64-bit mixing function.
///
/// Same as `mix_u64()` but takes a seed.
#[inline(always)]
pub fn mix_seed_u64(n: u64, seed: u64) -> u64 {
// We rotate the bits of `seed` so it's unlikely to interact with `n`
// in bad ways if they're both e.g. incrementing. The particular
// rotation constant used here isn't special.
mix_u64(n ^ seed.rotate_left(47))
}