1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358
// std
use std::borrow::Borrow;
use std::cell::Cell;
use std::sync::Arc;
// pbrt
// use crate::core::bssrdf::Bssrdf;
use crate::core::camera::Camera;
use crate::core::geometry::{vec3_abs_dot_nrmf, vec3_dot_nrmf};
use crate::core::geometry::{Bounds2i, Point2f, Ray, Vector3f};
use crate::core::integrator::uniform_sample_one_light;
use crate::core::interaction::{Interaction, MediumInteraction, SurfaceInteraction};
use crate::core::lightdistrib::create_light_sample_distribution;
use crate::core::lightdistrib::LightDistribution;
use crate::core::material::TransportMode;
use crate::core::pbrt::{Float, Spectrum};
use crate::core::reflection::BxdfType;
use crate::core::sampler::Sampler;
use crate::core::sampling::Distribution1D;
use crate::core::scene::Scene;
// see volpath.h
/// Accounts for scattering and attenuation from participating media
/// as well as scattering from surfaces - uses the render loop of a
/// [SamplerIntegrator](../../core/integrator/enum.SamplerIntegrator.html)
pub struct VolPathIntegrator {
// inherited from SamplerIntegrator (see integrator.h)
pub camera: Arc<Camera>,
pub sampler: Box<Sampler>,
pub pixel_bounds: Bounds2i,
// see volpath.h
pub max_depth: u32,
pub rr_threshold: Float, // 1.0
pub light_sample_strategy: String, // "spatial"
pub light_distribution: Option<Arc<LightDistribution>>,
}
impl VolPathIntegrator {
pub fn new(
max_depth: u32,
camera: Arc<Camera>,
sampler: Box<Sampler>,
pixel_bounds: Bounds2i,
rr_threshold: Float,
light_sample_strategy: String,
) -> Self {
VolPathIntegrator {
camera,
sampler,
pixel_bounds,
max_depth,
rr_threshold,
light_sample_strategy,
light_distribution: None,
}
}
pub fn preprocess(&mut self, scene: &Scene) {
self.light_distribution =
create_light_sample_distribution(self.light_sample_strategy.clone(), scene);
}
pub fn li(
&self,
r: &mut Ray,
scene: &Scene,
sampler: &mut Sampler,
// arena: &mut Arena,
_depth: i32,
) -> Spectrum {
// TODO: ProfilePhase p(Prof::SamplerIntegratorLi);
let mut l: Spectrum = Spectrum::default();
let mut beta: Spectrum = Spectrum::new(1.0 as Float);
let mut ray: Ray = Ray {
o: r.o,
d: r.d,
t_max: Cell::new(r.t_max.get()),
time: r.time,
differential: r.differential,
medium: r.medium.clone(),
};
let mut specular_bounce: bool = false;
let mut bounces: u32 = 0_u32;
// Added after book publication: etaScale tracks the
// accumulated effect of radiance scaling due to rays passing
// through refractive boundaries (see the derivation on p. 527
// of the third edition). We track this value in order to
// remove it from beta when we apply Russian roulette; this is
// worthwhile, since it lets us sometimes avoid terminating
// refracted rays that are about to be refracted back out of a
// medium and thus have their beta value increased.
let mut eta_scale: Float = 1.0;
loop {
let mut mi_opt: Option<MediumInteraction> = None;
// intersect _ray_ with scene and store intersection in _isect_
let mut isect: SurfaceInteraction = SurfaceInteraction::default();
if scene.intersect(&mut ray, &mut isect) {
// sample the participating medium, if present
if let Some(ref medium) = ray.medium {
let (spectrum, option) = medium.sample(&ray, sampler);
beta *= spectrum;
if let Some(mi) = option {
mi_opt = Some(mi);
}
}
if beta.is_black() {
break;
}
// handle an interaction with a medium or a surface
if let Some(mi) = mi_opt {
// terminate path if ray escaped or _maxDepth_ was reached
if bounces >= self.max_depth {
break;
}
let mi_p = mi.common.p;
// if mi.is_valid() {...}
if let Some(phase) = mi.clone().phase {
// TODO: ++volumeInteractions;
// handle scattering at point in medium for volumetric path tracer
if let Some(ref light_distribution) = self.light_distribution {
let distrib: Arc<Distribution1D> = light_distribution.lookup(&mi_p);
l += beta
* uniform_sample_one_light(
&mi as &dyn Interaction,
scene,
sampler,
true,
Some(&distrib),
);
let mut wi: Vector3f = Vector3f::default();
phase.sample_p(&(-ray.d), &mut wi, sampler.get_2d());
ray = mi.spawn_ray(&wi);
specular_bounce = false;
}
}
} else {
// TODO: ++surfaceInteractions;
// possibly add emitted light at intersection
if bounces == 0 || specular_bounce {
// add emitted light at path vertex
l += beta * isect.le(&-ray.d);
}
// terminate path if _maxDepth_ was reached
if bounces >= self.max_depth {
break;
}
// compute scattering functions and skip over medium boundaries
let mode: TransportMode = TransportMode::Radiance;
isect.compute_scattering_functions(&ray, true, mode);
if let Some(ref _bsdf) = isect.bsdf {
// we are fine (for below)
} else {
ray = isect.spawn_ray(&ray.d);
// bounces--;
continue;
}
if let Some(ref light_distribution) = self.light_distribution {
let light_distrib: Arc<Distribution1D> =
light_distribution.lookup(&isect.common.p);
// Sample illumination from lights to find
// attenuated path contribution.
let it: &SurfaceInteraction = isect.borrow();
l += beta
* uniform_sample_one_light(
it,
scene,
sampler,
true,
Some(&light_distrib),
);
if let Some(ref bsdf) = isect.bsdf {
// Sample BSDF to get new path direction
let wo: Vector3f = -ray.d;
let mut wi: Vector3f = Vector3f::default();
let mut pdf: Float = 0.0 as Float;
let bsdf_flags: u8 = BxdfType::BsdfAll as u8;
let mut sampled_type: u8 = u8::max_value(); // != 0
let f: Spectrum = bsdf.sample_f(
&wo,
&mut wi,
&sampler.get_2d(),
&mut pdf,
bsdf_flags,
&mut sampled_type,
);
if f.is_black() || pdf == 0.0 as Float {
break;
}
beta *= (f * vec3_abs_dot_nrmf(&wi, &isect.shading.n)) / pdf;
assert!(
!(beta.y().is_infinite()),
"[{:#?}, {:?}] = ({:#?} * dot({:#?}, {:#?})) / {:?}",
sampler.get_current_pixel(),
sampler.get_current_sample_number(),
f,
wi,
isect.shading.n,
pdf
);
specular_bounce = (sampled_type & BxdfType::BsdfSpecular as u8) != 0_u8;
if ((sampled_type & BxdfType::BsdfSpecular as u8) != 0_u8)
&& ((sampled_type & BxdfType::BsdfTransmission as u8) != 0_u8)
{
let eta: Float = bsdf.eta;
// Update the term that tracks radiance
// scaling for refraction depending on
// whether the ray is entering or leaving
// the medium.
if vec3_dot_nrmf(&wo, &isect.common.n) > 0.0 as Float {
eta_scale *= eta * eta;
} else {
eta_scale *= 1.0 as Float / (eta * eta);
}
}
ray = isect.spawn_ray(&wi);
// account for attenuated subsurface scattering, if applicable
if let Some(ref bssrdf) = isect.bssrdf {
if (sampled_type & BxdfType::BsdfTransmission as u8) != 0_u8 {
// importance sample the BSSRDF
let s2: Point2f = sampler.get_2d();
let s1: Float = sampler.get_1d();
let (s, pi_opt) = bssrdf.sample_s(
// the next three (extra) parameters are used for SeparableBssrdfAdapter
bssrdf.clone(),
bssrdf.mode,
bssrdf.eta,
// done
scene,
s1,
s2,
&mut pdf,
);
if s.is_black() || pdf == 0.0 as Float {
break;
}
assert!(!(beta.y().is_infinite()));
beta *= s / pdf;
if let Some(pi) = pi_opt {
// account for the direct subsurface scattering component
let distrib: Arc<Distribution1D> =
light_distribution.lookup(&pi.common.p);
l += beta
* uniform_sample_one_light(
&pi,
scene,
sampler,
true,
Some(&distrib),
);
// account for the indirect subsurface scattering component
let mut wi: Vector3f = Vector3f::default();
let mut pdf: Float = 0.0 as Float;
let bsdf_flags: u8 = BxdfType::BsdfAll as u8;
let mut sampled_type: u8 = u8::max_value(); // != 0
if let Some(ref bsdf) = pi.bsdf {
let f: Spectrum = bsdf.sample_f(
&pi.common.wo,
&mut wi,
&sampler.get_2d(),
&mut pdf,
bsdf_flags,
&mut sampled_type,
);
if f.is_black() || pdf == 0.0 as Float {
break;
}
beta *= f * vec3_abs_dot_nrmf(&wi, &pi.shading.n) / pdf;
assert!(!(beta.y().is_infinite()));
specular_bounce = (sampled_type
& BxdfType::BsdfSpecular as u8)
!= 0_u8;
ray = pi.spawn_ray(&wi);
} else {
panic!("no pi.bsdf found");
}
} else {
panic!("bssrdf.sample_s() did return (s, None)");
}
}
}
} else {
println!("TODO: if let Some(ref bsdf) = isect.bsdf failed");
}
}
}
// Possibly terminate the path with Russian roulette.
// Factor out radiance scaling due to refraction in rr_beta.
let rr_beta: Spectrum = beta * eta_scale;
if rr_beta.max_component_value() < self.rr_threshold && bounces > 3 {
let q: Float =
(0.05 as Float).max(1.0 as Float - rr_beta.max_component_value());
if sampler.get_1d() < q {
break;
}
beta /= 1.0 as Float - q;
assert!(!(beta.y().is_infinite()));
}
} else {
// sample the participating medium, if present
if let Some(ref medium) = ray.medium {
let (spectrum, option) = medium.sample(&ray, sampler);
beta *= spectrum;
if let Some(mi) = option {
mi_opt = Some(mi);
}
}
if beta.is_black() {
break;
}
// handle an interaction with a medium
if let Some(mi) = mi_opt {
// terminate path if ray escaped or _maxDepth_ was reached
if bounces >= self.max_depth {
break;
}
let mi_p = mi.common.p;
// if mi.is_valid() {...}
if let Some(phase) = mi.clone().phase {
// TODO: ++volumeInteractions;
// handle scattering at point in medium for volumetric path tracer
if let Some(ref light_distribution) = self.light_distribution {
let distrib: Arc<Distribution1D> = light_distribution.lookup(&mi_p);
l += beta
* uniform_sample_one_light(
&mi as &dyn Interaction,
scene,
sampler,
true,
Some(&distrib),
);
let mut wi: Vector3f = Vector3f::default();
phase.sample_p(&(-ray.d), &mut wi, sampler.get_2d());
ray = mi.spawn_ray(&wi);
specular_bounce = false;
}
}
}
// add emitted light from the environment
if bounces == 0 || specular_bounce {
for light in &scene.infinite_lights {
l += beta * light.le(&mut ray);
}
}
// terminate path if ray escaped
break;
}
bounces += 1_u32;
}
l
}
pub fn get_camera(&self) -> Arc<Camera> {
self.camera.clone()
}
pub fn get_sampler(&self) -> &Sampler {
&self.sampler
}
pub fn get_pixel_bounds(&self) -> Bounds2i {
self.pixel_bounds
}
}