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Fix some Microfacet bugs

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This commit is contained in:
hal8174 2024-12-28 23:27:21 +01:00
parent 745b7d2602
commit c26285a98e
5 changed files with 119 additions and 29 deletions
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18
Cargo.lock generated
View file

@ -1382,6 +1382,12 @@ dependencies = [
"windows-targets 0.52.6",
]
[[package]]
name = "libm"
version = "0.2.11"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "8355be11b20d696c8f18f6cc018c4e372165b1fa8126cef092399c9951984ffa"
[[package]]
name = "libredox"
version = "0.1.3"
@ -1662,6 +1668,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
dependencies = [
"autocfg",
"libm",
]
[[package]]
@ -2105,6 +2112,16 @@ dependencies = [
"getrandom",
]
[[package]]
name = "rand_distr"
version = "0.4.3"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "32cb0b9bc82b0a0876c2dd994a7e7a2683d3e7390ca40e6886785ef0c7e3ee31"
dependencies = [
"num-traits",
"rand",
]
[[package]]
name = "rav1e"
version = "0.7.1"
@ -2201,6 +2218,7 @@ dependencies = [
name = "ray-tracing-material"
version = "0.1.0"
dependencies = [
"rand_distr",
"ray-tracing-core",
]

27
ray-tracing-material-visualizer/src/bin/fresnel.rs Normal file
View file

@ -0,0 +1,27 @@
use plotters::prelude::*;
use ray_tracing_core::prelude::*;
use ray_tracing_material::microfacet::fresnel_real;
fn main() -> Result<(), Box<dyn std::error::Error>> {
let root = BitMapBackend::new("fresnel.png", (640, 480)).into_drawing_area();
root.fill(&WHITE)?;
let mut chart = ChartBuilder::on(&root)
.caption("Fresnel", ("sans-serif", 50).into_font())
.margin(5)
.x_label_area_size(30)
.y_label_area_size(30)
.build_cartesian_2d(0.0..FloatConsts::FRAC_PI_2, 0.0..1.0f32)?;
chart.configure_mesh().draw()?;
chart.draw_series(LineSeries::new(
(0..=300)
.map(|x| x as Float * FloatConsts::FRAC_PI_2 / 300.0)
.map(|x| (x, fresnel_real(Float::cos(x), 1.0, 1.5))),
&RED,
))?;
root.present()?;
Ok(())
}

45
ray-tracing-material-visualizer/src/main.rs
View file

@ -1,3 +1,5 @@
use core::f64;
use plotters::{
chart::ChartBuilder,
coord::Shift,
@ -19,17 +21,17 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
let color = Color::new(1.0, 1.0, 1.0);
let m = Mirror::new(color);
generate_chart("mirror.png", &m, 2, w_in)?;
// let m = Mirror::new(color);
// generate_chart("mirror.png", &m, 2, w_in)?;
let m = DiffuseMaterial::new(color);
generate_chart("diffuse.png", &m, 100, w_in)?;
// let m = DiffuseMaterial::new(color);
// generate_chart("diffuse.png", &m, 100, w_in)?;
let m = Microfacet::new(BeckmannDistribution::new(0.5), color);
generate_chart("microfacet.png", &m, 100, w_in)?;
let m = Microfacet::new(BeckmannDistribution::new(0.1), color);
generate_chart("microfacet.png", &m, 400, w_in)?;
let m = OrenNayar::new(0.5, color);
generate_chart("oren-nayar.png", &m, 100, w_in)?;
// let m = OrenNayar::new(0.5, color);
// generate_chart("oren-nayar.png", &m, 100, w_in)?;
Ok(())
}
@ -52,7 +54,10 @@ fn generate_chart<M: Material<SmallRng>>(
let eval_histogram = create_histogram_evaled(m, 400, 400, executions, w_in);
let sample_histogram = create_historgram_sampled(m, 400, 400, executions, w_in);
let max = Float::max(eval_histogram.max(), sample_histogram.max());
let max = Float::max(
Float::max(eval_histogram.max(), sample_histogram.max()),
Float::MIN_POSITIVE,
);
let area = areas[0].titled("Evaled", ("sans-serif", 30))?;
plot_material(&area, eval_histogram, max)?;
@ -142,7 +147,7 @@ where
_ => unreachable!(),
};
assert!(f >= 0.0 && f <= max && f.is_finite(), "{f}");
assert!(f >= 0.0 && f <= max && f.is_finite() && max != 0.0, "{f}");
let color = plotters::prelude::ViridisRGB::get_color_normalized(f, 0.0, max);
if dir.y() < 0.0 {
lower_area.draw_pixel((dir.x() as f64, dir.z() as f64), &color)?;
@ -160,7 +165,7 @@ struct Histogram {
inserted: usize,
width: usize,
height: usize,
max: f32,
max: f64,
}
impl Histogram {
@ -194,14 +199,15 @@ impl Histogram {
fn insert(&mut self, pos: Dir3, value: Color) {
let index = self.discretize(pos);
self.data[index] += value;
self.max = f32::max(self.max, self.data[index].r());
self.max = f32::max(self.max, self.data[index].g());
self.max = f32::max(self.max, self.data[index].b());
self.max = f64::max(self.max, self.data[index].r() as f64);
self.max = f64::max(self.max, self.data[index].g() as f64);
self.max = f64::max(self.max, self.data[index].b() as f64);
self.inserted += 1;
}
fn max(&self) -> f32 {
self.max / (self.inserted as f32)
dbg!(self.max, self.inserted, self.inserted as f64);
(self.max / (self.inserted as f64)) as f32
}
fn iter(&self) -> impl Iterator<Item = (Dir3, Color)> + use<'_> {
@ -280,8 +286,11 @@ fn create_historgram_sampled<M: Material<SmallRng>>(
&& sample.color().g() >= 0.0
&& sample.color().g().is_finite()
&& sample.color().b() >= 0.0
&& sample.color().b().is_finite(),
"w_in: {w_in:?}; w_out: {:?}; material: {m:?}; color: {:?}",
&& sample.color().b().is_finite()
&& (-1.0..=1.0).contains(&sample.w_out().x())
&& (-1.0..=1.0).contains(&sample.w_out().y())
&& (-1.0..=1.0).contains(&sample.w_out().z()),
"invalid_sampling: w_in: {w_in:?}; w_out: {:?}; material: {m:?}; color: {:?}",
sample.w_out(),
sample.color()
);
@ -317,7 +326,7 @@ fn create_histogram_evaled<M: Material<SmallRng>>(
&& color.g().is_finite()
&& color.b() >= 0.0
&& color.b().is_finite(),
"w_in: {w_in:?}; w_out: {w_out:?}; material: {m:?}; color: {color:?}"
"invalid_eval: w_in: {w_in:?}; w_out: {w_out:?}; material: {m:?}; color: {color:?}"
);
(w_out, color)

1
ray-tracing-material/Cargo.toml
View file

@ -4,4 +4,5 @@ version = "0.1.0"
edition = "2021"
[dependencies]
rand_distr = "0.4.3"
ray-tracing-core = { path = "../ray-tracing-core" }

45
ray-tracing-material/src/microfacet.rs
View file

@ -1,3 +1,4 @@
use rand_distr::{Distribution, Normal};
use ray_tracing_core::{material::Material, prelude::*};
use std::fmt::Debug;
@ -13,7 +14,7 @@ impl<D: MicrofacetDistribution + Debug> Microfacet<D> {
}
}
fn fresnel_real(cos_theta_in: Float, nu1: Float, nu2: Float) -> Float {
pub fn fresnel_real(cos_theta_in: Float, nu1: Float, nu2: Float) -> Float {
let nu_rel = nu1 / nu2;
let cos_theta_tr = Float::sqrt(1.0 - nu_rel * nu_rel * (1.0 - cos_theta_in * cos_theta_in));
@ -34,12 +35,28 @@ impl<R: Rng, D: MicrofacetDistribution + Debug + Sync> Material<R> for Microface
let g = self.dist.g1(w_in, w_h) * self.dist.g1(w_out, w_h);
self.color * fresnel_real(Dir3::dot(w_in, w_h), 1.0, 1.3) * g * self.dist.d(w_h)
self.color * fresnel_real(Dir3::dot(w_in, w_h), 1.0, 1.5) * g * self.dist.d(w_h)
/ (4.0 * w_in.y() * w_out.y()).max(0.0)
} else {
Color::black()
}
}
fn sample(&self, w_in: Dir3, rng: &mut R) -> ray_tracing_core::material::SampleResult {
let w_h = self.dist.sample_d(rng);
let w_out = (2.0 * (Dir3::dot(w_in, w_h) * w_h) - w_in).normalize();
if w_out.y() > 0.0 {
let g = self.dist.g1(w_in, w_h) * self.dist.g1(w_out, w_h);
ray_tracing_core::material::SampleResult::new(
w_out,
self.color * fresnel_real(Dir3::dot(w_in, w_h), 1.0, 1.5) * g,
)
} else {
ray_tracing_core::material::SampleResult::new(w_out, Color::black())
}
}
}
#[derive(Debug)]
@ -57,17 +74,24 @@ impl MicrofacetDistribution for BeckmannDistribution {
fn g1(&self, w: Dir3, w_h: Dir3) -> Float {
if w.y() > 0.0 && Dir3::dot(w, w_h) > 0.0 {
let cos_theta = w.y();
let a = self.alpha * (Float::sqrt(1.0 - cos_theta * cos_theta) / cos_theta);
let a = 1.0 / (self.alpha * (Float::sqrt(1.0 - cos_theta * cos_theta) / cos_theta));
if a < 1.6 {
(3.535 * a + 2.181 * a * a) / (1.0 + 2.276 * a + 2.577 * a * a)
} else {
1.0
}
} else {
0.0
}
}
fn d(&self, w_h: Dir3) -> Float {
if w_h.y() > 0.0 {
let cos_theta_squared = w_h.y() * w_h.y();
1.0 / (FloatConsts::PI
let tan_theta_squared =
w_h.x() * w_h.x() / cos_theta_squared + w_h.z() * w_h.z() / cos_theta_squared;
Float::exp(-tan_theta_squared / (self.alpha * self.alpha))
/ (FloatConsts::PI
* self.alpha
* self.alpha
* cos_theta_squared
@ -76,6 +100,17 @@ impl MicrofacetDistribution for BeckmannDistribution {
0.0
}
}
fn sample_d<R: Rng>(&self, rng: &mut R) -> Dir3 {
let n = Normal::new(0.0, self.alpha).unwrap();
let mx = n.sample(rng);
let mz = n.sample(rng);
let y = Float::sqrt(1.0 / (mx * mx + 1.0 + mz * mz));
Dir3::new(mx * y, y, mz * y).normalize()
}
}
pub trait MicrofacetDistribution {
@ -83,5 +118,5 @@ pub trait MicrofacetDistribution {
fn d(&self, w_h: Dir3) -> Float;
// fn sample_d(&self) -> Dir3;
fn sample_d<R: Rng>(&self, rng: &mut R) -> Dir3;
}