add interreflections

src/lib.rs

@@ -9,7 +9,7 @@ use crate::{
 	camera::OrbitalCamera,
 	ray::Ray,
 	render::lines::{LookParams, Mesh, Pipeline, Vertex},
-	trace::{Hit, Scene, Source, Sphere},
+	trace::{Hit, Lambertian, Reflector, Scene, Source, Sphere},
 };
 
 mod camera;
@@ -36,6 +36,14 @@ pub struct RedrawArgs {
 	pub light_spread: f32,
 	pub accum_sigma: f32,
 	pub accum_scale: f32,
+	pub reflections: u32,
+	pub show_axes: bool,
+	pub show_shapes: bool,
+	pub show_hit_emission: bool,
+	pub show_miss_emission: bool,
+	pub show_direct_hit: bool,
+	pub show_indirect_hit: bool,
+	pub show_light: bool,
 }
 
 pub struct Gpu {
@@ -163,7 +171,9 @@ impl Core {
 			depth_stencil_attachment: None,
 			..Default::default()
 		});
+		if args.show_axes {
 			self.pipeline.render(&mut pass, [&self.tripod]);
+		}
 
 		let source = Source {
 			position_yaw: args.light_position.yaw,
@@ -173,6 +183,7 @@ impl Core {
 			spread: args.light_spread,
 		};
 
+		if args.show_shapes {
 			let contour: Vec<Vertex> = loop_list(source.contour(17))
 				.map(|pos| Vertex {
 					pos,
@@ -181,6 +192,7 @@ impl Core {
 				.collect();
 			self.pipeline
 				.render(&mut pass, [&Mesh::new(&self.device, &contour)]);
+		}
 
 		const BASE_R: f32 = 2.;
 		const BASE_POS: Vec3 = vec3(0., 0., -BASE_R);
@@ -211,6 +223,7 @@ impl Core {
 		for ray in source_rays {
 			if let Some(hit) = scene.trace_ray(ray) {
 				hits.push(hit);
+				if args.show_hit_emission {
 					source_ray_display.extend([
 						Vertex {
 							pos: ray.base,
@@ -220,6 +233,10 @@ impl Core {
 							pos: ray.base + 0.1 * ray.dir,
 							color: vec3(0., 1., 0.),
 						},
+					]);
+				}
+				if args.show_direct_hit {
+					source_ray_display.extend([
 						Vertex {
 							pos: hit.incident.base - 0.02 * hit.incident.dir,
 							color: vec3(0., 0., 1.),
@@ -229,7 +246,9 @@ impl Core {
 							color: vec3(1., 1., 1.),
 						},
 					]);
+				}
 			} else {
+				if args.show_miss_emission {
 					source_ray_display.extend([
 						Vertex {
 							pos: ray.base,
@@ -242,28 +261,64 @@ impl Core {
 					]);
 				}
 			}
+		}
+		if args.reflections > 0 {
+			let mut hits1 = hits.clone();
+			for _ in 0..args.reflections {
+				let mut hits2: Vec<Hit> = Vec::with_capacity(hits1.len());
+				for hit in &hits1 {
+					let reflector = Lambertian;
+					let reflected = reflector.reflect(&mut prng, hit.normal, hit.incident.dir);
+					let ray = Ray::new(hit.incident.base, reflected);
+					let Some(hit2) = scene.trace_ray(ray) else {
+						continue;
+					};
+					hits2.push(hit2);
+					if args.show_indirect_hit {
+						source_ray_display.extend([
+							Vertex {
+								pos: hit2.incident.base - 0.02 * hit2.incident.dir,
+								color: vec3(1., 0., 1.),
+							},
+							Vertex {
+								pos: hit2.incident.base,
+								color: vec3(1., 1., 1.),
+							},
+						]);
+					}
+				}
+				hits.extend(&hits2);
+				hits1 = hits2;
+			}
+		}
 		let mut camera_ray_display: Vec<Vertex> = Vec::with_capacity(camera_rays.len());
+		if args.show_light {
 			let sigma2 = args.accum_sigma.powi(2);
-		let weight = (2. * PI * sigma2).sqrt().recip() * args.accum_scale;
+			let accum_normalizator = (2. * PI * sigma2).sqrt().recip();
 			for ray in camera_rays {
 				let Some(hit) = scene.trace_ray(ray) else {
 					continue;
 				};
-			let mut value = 0.0f32;
+				let mut total_cd = 0.0f32;
 				for light_hit in &hits {
 					let d2 = hit.incident.base.distance_squared(light_hit.incident.base);
-				if d2 > 3. * sigma2 {
+					if d2 > 9. * sigma2 {
 						continue;
 					}
+					assert!(hit.normal.is_normalized());
 					assert!(hit.incident.dir.is_normalized());
-				let radiance = hit.normal.dot(-hit.incident.dir);
-				let w = (-0.5 * d2 / sigma2).exp();
-				value += w * radiance;
+					let reflector = Lambertian;
+					let in_lm = 1.0;
+					let out_cd = in_lm
+						* hit.normal.dot(-hit.incident.dir)
+						* reflector.brdf(hit.normal, hit.incident.dir, -ray.dir);
+					let weight = accum_normalizator * (-0.5 * d2 / sigma2).exp();
+					total_cd += weight * out_cd;
 				}
-			value *= weight;
-			value = 3. * (1. - (1. + value).recip());
+				let brightness = 3. * (1. - (1. + total_cd * args.accum_scale).recip());
 				let r = args.accum_sigma;
-			let color = vec3(value, value - 1., value - 2.).clamp(Vec3::splat(0.), Vec3::splat(1.));
+				let color = vec3(brightness, brightness - 1., brightness - 2.)
+					.clamp(Vec3::splat(0.), Vec3::splat(1.));
 				let vertex = |off: Vec3| Vertex {
 					pos: hit.incident.base + r * off,
 					color,
@@ -277,10 +332,15 @@ impl Core {
 					vertex(Vec3::Z),
 				]);
 			}
+		}
+		if !source_ray_display.is_empty() {
 			self.pipeline
 				.render(&mut pass, [&Mesh::new(&self.device, &source_ray_display)]);
+		}
+		if !camera_ray_display.is_empty() {
 			self.pipeline
 				.render(&mut pass, [&Mesh::new(&self.device, &camera_ray_display)]);
+		}
 
 		drop(pass);
 		self.queue.submit(std::iter::once(encoder.finish()));

src/trace.rs

@@ -1,7 +1,7 @@
 use std::f32::consts::PI;
 
 use glam::{Mat4, Vec2, Vec3, vec3};
-use rand_distr::Distribution;
+use rand_distr::{Distribution, UnitSphere};
 
 use crate::{camera::OrbitalCamera, ray::Ray};
 
@@ -120,10 +120,12 @@ pub struct Hit {
 
 impl Scene {
 	pub fn trace_ray(&self, ray: Ray) -> Option<Hit> {
+		const EPS: f32 = -1e-3;
 		let hit = self
 			.objects
 			.iter()
 			.filter_map(|obj| obj.trace_ray(ray))
+			.filter(|h| h.dist >= EPS)
 			.min_by(|a, b| f32::total_cmp(&a.dist, &b.dist))?;
 		Some(Hit {
 			incident: Ray {
@@ -134,3 +136,27 @@ impl Scene {
 		})
 	}
 }
+
+pub trait Reflector {
+	fn brdf(&self, normal: Vec3, incident: Vec3, reflected: Vec3) -> f32 /* 1/sr */;
+	fn reflect(&self, rgen: &mut impl rand::Rng, normal: Vec3, incident: Vec3) -> Vec3;
+}
+
+pub struct Lambertian;
+
+impl Reflector for Lambertian {
+	fn brdf(&self, _normal: Vec3, _incident: Vec3, _reflected: Vec3) -> f32 {
+		1. / PI
+	}
+
+	fn reflect(&self, rgen: &mut impl rand::Rng, normal: Vec3, _incident: Vec3) -> Vec3 {
+		let sphere: Vec3 = UnitSphere.sample(rgen).into();
+		let sphere_n = normal.dot(sphere); // uniform on [-1, 1]!
+		let sphere_t = sphere - sphere_n * normal;
+
+		let out_n_len2 = sphere_n.abs();
+		let out_t = (1. + out_n_len2).recip().sqrt() * sphere_t;
+		let out_n = out_n_len2.sqrt() * normal;
+		out_t + out_n
+	}
+}

ui/src/api.hxx

@@ -8,18 +8,26 @@ namespace ffi {
 struct Core;
 
 struct SphericalPosition {
-	float yaw;
-	float pitch;
-	float distance;
+	float yaw = 0.;
+	float pitch = 0.;
+	float distance = 1.;
 };
 
 struct RedrawArgs {
 	SphericalPosition camera_position;
 	SphericalPosition light_position;
-	float light_radius;
-	float light_spread;
-	float accum_sigma;
-	float accum_scale;
+	float light_radius = 1.;
+	float light_spread = 0.;
+	float accum_sigma = 1.;
+	float accum_scale = 1.;
+	std::uint32_t reflections = 0;
+	bool show_axes = true;
+	bool show_shapes = true;
+	bool show_hit_emission = true;
+	bool show_miss_emission = true;
+	bool show_direct_hit = true;
+	bool show_indirect_hit = true;
+	bool show_light = true;
 };
 } // namespace ffi
 

ui/src/main_window.cxx

@@ -20,24 +20,34 @@ void PhotonLight::updateView() {
 		.camera_position = SphericalPosition{
 			.yaw = deg_to_rad(m_ui->cameraYaw->value()),
 			.pitch = deg_to_rad(m_ui->cameraPitch->value()),
-			.distance = 3.0,
+			.distance = m_ui->cameraDistance->value() / 10.0f,
 		},
 		.light_position = SphericalPosition{
 			.yaw = deg_to_rad(m_ui->lightYaw->value()),
 			.pitch = deg_to_rad(m_ui->lightPitch->value()),
-			.distance = 1.0,
+			.distance = m_ui->lightDistance->value() / 10.0f,
 		},
 		.light_radius = 0.125,
 		.light_spread = 0.125,
 		.accum_sigma = exp10f(m_ui->accumSigma->value() / 25.0),
 		.accum_scale = exp10f(m_ui->accumScale->value() / 25.0),
+		.reflections = std::uint32_t(m_ui->reflections->value()),
+		.show_axes = m_ui->displayAxes->isChecked(),
+		.show_shapes = m_ui->displayShapes->isChecked(),
+		.show_hit_emission = m_ui->displayEmitted->isChecked(),
+		.show_miss_emission = m_ui->displayEmitted->isChecked(),
+		.show_direct_hit = m_ui->displayDirectHits->isChecked(),
+		.show_indirect_hit = m_ui->displayIndirectHits->isChecked(),
+		.show_light = m_ui->displayResult->isChecked(),
 	};
 	m_ui->cameraYawLabel->setText(tr("Yaw: %1 deg").arg(QString::number(qRadiansToDegrees(args.camera_position.yaw))));
 	m_ui->cameraPitchLabel->setText(tr("Pitch: %1 deg").arg(QString::number(qRadiansToDegrees(args.camera_position.pitch))));
+	m_ui->cameraDistanceLabel->setText(tr("Distance: %1").arg(QString::number(args.camera_position.distance)));
 	m_ui->lightYawLabel->setText(tr("Yaw: %1 deg").arg(QString::number(qRadiansToDegrees(args.light_position.yaw))));
 	m_ui->lightPitchLabel->setText(tr("Pitch: %1 deg").arg(QString::number(qRadiansToDegrees(args.light_position.pitch))));
-	m_ui->accumSigmaLabel->setText(tr("Sigma: %1").arg(QString::number(args.accum_sigma, 'f', 3)));
-	m_ui->accumScaleLabel->setText(tr("Scale: %1").arg(QString::number(args.accum_scale, 'f', 3)));
+	m_ui->lightDistanceLabel->setText(tr("Distance: %1").arg(QString::number(args.light_position.distance)));
+	m_ui->accumSigmaLabel->setText(tr("Averaging radius: %1").arg(QString::number(args.accum_sigma, 'f', 3)));
+	m_ui->accumScaleLabel->setText(tr("Brightness: %1").arg(QString::number(args.accum_scale, 'f', 3)));
 	m_ui->viewport->setView(args);
 }
 

ui/src/main_window.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>800</width>
-    <height>600</height>
+    <width>1600</width>
+    <height>1200</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -25,7 +25,7 @@
     <rect>
      <x>0</x>
      <y>0</y>
-     <width>800</width>
+     <width>1600</width>
      <height>38</height>
     </rect>
    </property>
@@ -98,6 +98,26 @@
           </property>
          </widget>
         </item>
+        <item>
+         <widget class="QLabel" name="cameraDistanceLabel">
+          <property name="text">
+           <string>Distance</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSlider" name="cameraDistance">
+          <property name="maximum">
+           <number>50</number>
+          </property>
+          <property name="value">
+           <number>30</number>
+          </property>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </item>
@@ -159,19 +179,39 @@
           </property>
          </widget>
         </item>
+        <item>
+         <widget class="QLabel" name="lightDistanceLabel">
+          <property name="text">
+           <string>Distance</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSlider" name="lightDistance">
+          <property name="maximum">
+           <number>50</number>
+          </property>
+          <property name="value">
+           <number>10</number>
+          </property>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </item>
      <item>
       <widget class="QGroupBox" name="groupBox_3">
        <property name="title">
-        <string>Accumulating</string>
+        <string>Lighting</string>
        </property>
        <layout class="QVBoxLayout" name="verticalLayout_4">
         <item>
          <widget class="QLabel" name="accumSigmaLabel">
           <property name="text">
-           <string>Sigma</string>
+           <string>Averaging radius</string>
           </property>
          </widget>
         </item>
@@ -194,7 +234,7 @@
         <item>
          <widget class="QLabel" name="accumScaleLabel">
           <property name="text">
-           <string>Scale</string>
+           <string>Brightness</string>
           </property>
          </widget>
         </item>
@@ -214,6 +254,92 @@
           </property>
          </widget>
         </item>
+        <item>
+         <widget class="QLabel" name="label">
+          <property name="text">
+           <string>Reflections</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSpinBox" name="reflections">
+          <property name="maximum">
+           <number>20</number>
+          </property>
+          <property name="value">
+           <number>2</number>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </widget>
+     </item>
+     <item>
+      <widget class="QGroupBox" name="groupBox_4">
+       <property name="title">
+        <string>Show</string>
+       </property>
+       <layout class="QVBoxLayout" name="verticalLayout_5">
+        <item>
+         <widget class="QCheckBox" name="displayAxes">
+          <property name="text">
+           <string>Axes</string>
+          </property>
+          <property name="checked">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QCheckBox" name="displayShapes">
+          <property name="text">
+           <string>Shapes</string>
+          </property>
+          <property name="checked">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QCheckBox" name="displayEmitted">
+          <property name="text">
+           <string>Emitted rays</string>
+          </property>
+          <property name="checked">
+           <bool>false</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QCheckBox" name="displayDirectHits">
+          <property name="text">
+           <string>Direct incident rays</string>
+          </property>
+          <property name="checked">
+           <bool>false</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QCheckBox" name="displayIndirectHits">
+          <property name="text">
+           <string>Indirect incident rays</string>
+          </property>
+          <property name="checked">
+           <bool>false</bool>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QCheckBox" name="displayResult">
+          <property name="text">
+           <string>Average light</string>
+          </property>
+          <property name="checked">
+           <bool>true</bool>
+          </property>
+         </widget>
+        </item>
        </layout>
       </widget>
      </item>
@@ -251,8 +377,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>688</x>
-     <y>159</y>
+     <x>1585</x>
+     <y>169</y>
     </hint>
     <hint type="destinationlabel">
      <x>403</x>
@@ -267,8 +393,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>688</x>
-     <y>215</y>
+     <x>1585</x>
+     <y>225</y>
     </hint>
     <hint type="destinationlabel">
      <x>403</x>
@@ -283,8 +409,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>688</x>
-     <y>319</y>
+     <x>1585</x>
+     <y>385</y>
     </hint>
     <hint type="destinationlabel">
      <x>403</x>
@@ -299,8 +425,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>688</x>
-     <y>375</y>
+     <x>1585</x>
+     <y>441</y>
     </hint>
     <hint type="destinationlabel">
      <x>403</x>
@@ -315,8 +441,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>729</x>
-     <y>479</y>
+     <x>1585</x>
+     <y>601</y>
     </hint>
     <hint type="destinationlabel">
      <x>399</x>
@@ -331,8 +457,8 @@
    <slot>updateView()</slot>
    <hints>
     <hint type="sourcelabel">
-     <x>729</x>
-     <y>535</y>
+     <x>1585</x>
+     <y>657</y>
     </hint>
     <hint type="destinationlabel">
      <x>399</x>
@@ -340,6 +466,150 @@
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>cameraDistance</sender>
+   <signal>valueChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>271</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>lightDistance</sender>
+   <signal>valueChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>487</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayAxes</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>799</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayDirectHits</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>901</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayEmitted</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>867</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayIndirectHits</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>935</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayResult</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>969</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>displayShapes</sender>
+   <signal>stateChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>833</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>reflections</sender>
+   <signal>valueChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>1489</x>
+     <y>712</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>799</x>
+     <y>599</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
  <slots>
   <slot>updateView()</slot>