basic two-way tracing

src/lib.rs

@@ -2,10 +2,12 @@
 
 use std::{convert::identity, error::Error, f32::consts::PI};
 
-use glam::{Mat4, UVec2, Vec3, vec3};
+use glam::{Mat4, UVec2, Vec2, Vec3, vec3};
+use rand_distr::Distribution as _;
 
 use crate::{
 	camera::OrbitalCamera,
+	ray::Ray,
 	render::lines::{LookParams, Mesh, Pipeline, Vertex},
 	trace::{Scene, Source, Sphere},
 };
@@ -32,6 +34,8 @@ pub struct RedrawArgs {
 	pub light_position: SphericalPosition,
 	pub light_radius: f32,
 	pub light_spread: f32,
+	pub accum_sigma: f32,
+	pub accum_scale: f32,
 }
 
 pub struct Gpu {
@@ -84,6 +88,22 @@ fn loop_list_ex<T: Clone, U>(
 	}
 }
 
+impl OrbitalCamera {
+	fn make_ray(&self, rng: &mut impl rand::Rng) -> Ray {
+		let off: f32 = rand_distr::StandardUniform.sample(rng);
+		let side: Vec2 = rand_distr::UnitCircle.sample(rng).into();
+
+		let m = self.transform().inverse();
+		let fwd = 1. - 0.1 * off;
+		let side_scale = (1. - fwd.powi(2)).sqrt();
+		let dir = Vec3::from((side_scale * side, fwd));
+		Ray {
+			base: self.position(),
+			dir: m.transform_vector3(dir),
+		}
+	}
+}
+
 impl Core {
 	pub fn new(gpu: Gpu) -> Self {
 		let Gpu {
@@ -189,36 +209,77 @@ impl Core {
 		};
 
 		let mut prng = rand_pcg::Pcg64::new(42, 0);
-		let rays: Vec<Vertex> = (0..10000)
+		let source_rays: Vec<Ray> = (0..10240).map(|_| source.make_ray(&mut prng)).collect();
-			.flat_map(|_| {
+		let camera_rays: Vec<Ray> = (0..1024).map(|_| camera.make_ray(&mut prng)).collect();
-				let ray = source.make_ray(&mut prng);
+		let mut source_ray_display: Vec<Vertex> = Vec::with_capacity(source_rays.len());
-				if let Some(ray) = scene.trace_ray(ray) {
+		let mut hits: Vec<Ray> = Vec::with_capacity(source_rays.len());
-					[
+		for ray in source_rays {
-						Vertex {
+			if let Some(hit) = scene.trace_ray(ray) {
-							pos: ray.base - 0.02 * ray.dir,
+				hits.push(hit);
-							color: vec3(1., 1., 1.),
+				source_ray_display.extend([
-						},
+					Vertex {
-						Vertex {
+						pos: ray.base,
-							pos: ray.base,
+						color: vec3(1., 1., 1.),
-							color: vec3(0., 1., 0.),
+					},
-						},
+					Vertex {
-					]
+						pos: ray.base + 0.1 * ray.dir,
-				} else {
+						color: vec3(0., 1., 0.),
-					[
+					},
-						Vertex {
+					Vertex {
-							pos: ray.base,
+						pos: hit.base - 0.02 * hit.dir,
-							color: vec3(1., 1., 1.),
+						color: vec3(0., 0., 1.),
-						},
+					},
-						Vertex {
+					Vertex {
-							pos: ray.base + 0.1 * ray.dir,
+						pos: hit.base,
-							color: vec3(1., 0., 0.),
+						color: vec3(1., 1., 1.),
-						},
+					},
-					]
+				]);
-				}
+			} else {
-			})
+				source_ray_display.extend([
-			.collect();
+					Vertex {
+						pos: ray.base,
+						color: vec3(1., 1., 1.),
+					},
+					Vertex {
+						pos: ray.base + 0.1 * ray.dir,
+						color: vec3(1., 0., 0.),
+					},
+				]);
+			}
+		}
+		let mut camera_ray_display: Vec<Vertex> = Vec::with_capacity(camera_rays.len());
+		let sigma2 = args.accum_sigma.powi(2);
+		let weight = (2. * PI * sigma2).sqrt().recip() * args.accum_scale;
+		for ray in camera_rays {
+			let Some(hit) = scene.trace_ray(ray) else {
+				continue;
+			};
+			let mut value = 0.0f32;
+			for light_hit in &hits {
+				let d2 = hit.base.distance_squared(light_hit.base);
+				let w = (-0.5 * d2 / sigma2).exp();
+				value += w;
+			}
+			value *= weight;
+			let r = 0.01;
+			let color = vec3(value, value - 1., value - 2.).clamp(Vec3::splat(0.), Vec3::splat(1.));
+			let vertex = |off: Vec3| Vertex {
+				pos: hit.base + r * off,
+				color,
+			};
+			camera_ray_display.extend([
+				vertex(-Vec3::X),
+				vertex(Vec3::X),
+				vertex(-Vec3::Y),
+				vertex(Vec3::Y),
+				vertex(-Vec3::Z),
+				vertex(Vec3::Z),
+			]);
+		}
 		self.pipeline
-			.render(&mut pass, [&Mesh::new(&self.device, &rays)]);
+			.render(&mut pass, [&Mesh::new(&self.device, &source_ray_display)]);
+		self.pipeline
+			.render(&mut pass, [&Mesh::new(&self.device, &camera_ray_display)]);
 
 		drop(pass);
 		self.queue.submit(std::iter::once(encoder.finish()));

ui/src/api.hxx

@@ -18,6 +18,8 @@ struct RedrawArgs {
 	SphericalPosition light_position;
 	float light_radius;
 	float light_spread;
+	float accum_sigma;
+	float accum_scale;
 };
 } // namespace ffi
 

ui/src/main_window.cxx

@@ -16,7 +16,7 @@ float deg_to_rad(float val) {
 }
 
 void PhotonLight::updateView() {
-	m_ui->viewport->setView(RedrawArgs{
+	RedrawArgs args{
 		.camera_position = SphericalPosition{
 			.yaw = deg_to_rad(m_ui->cameraYaw->value()),
 			.pitch = deg_to_rad(m_ui->cameraPitch->value()),
@@ -29,7 +29,16 @@ void PhotonLight::updateView() {
 		},
 		.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),
+	};
+	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->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)));
+	m_ui->accumScaleLabel->setText(tr("Scale: %1").arg(QString::number(args.accum_scale)));
+	m_ui->viewport->setView(args);
 }
 
 #include "moc_main_window.cpp"

ui/src/main_window.ui

@@ -47,7 +47,7 @@
        </property>
        <layout class="QVBoxLayout" name="verticalLayout">
         <item>
-         <widget class="QLabel" name="label">
+         <widget class="QLabel" name="cameraYawLabel">
           <property name="text">
            <string>Yaw</string>
           </property>
@@ -73,7 +73,7 @@
          </widget>
         </item>
         <item>
-         <widget class="QLabel" name="label_2">
+         <widget class="QLabel" name="cameraPitchLabel">
           <property name="text">
            <string>Pitch</string>
           </property>
@@ -108,7 +108,7 @@
        </property>
        <layout class="QVBoxLayout" name="verticalLayout_3">
         <item>
-         <widget class="QLabel" name="label_3">
+         <widget class="QLabel" name="lightYawLabel">
           <property name="text">
            <string>Yaw</string>
           </property>
@@ -131,7 +131,7 @@
          </widget>
         </item>
         <item>
-         <widget class="QLabel" name="label_4">
+         <widget class="QLabel" name="lightPitchLabel">
           <property name="text">
            <string>Pitch</string>
           </property>
@@ -162,6 +162,55 @@
        </layout>
       </widget>
      </item>
+     <item>
+      <widget class="QGroupBox" name="groupBox_3">
+       <property name="title">
+        <string>Accumulating</string>
+       </property>
+       <layout class="QVBoxLayout" name="verticalLayout_4">
+        <item>
+         <widget class="QLabel" name="accumSigmaLabel">
+          <property name="text">
+           <string>Sigma</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSlider" name="accumSigma">
+          <property name="minimum">
+           <number>-100</number>
+          </property>
+          <property name="maximum">
+           <number>100</number>
+          </property>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QLabel" name="accumScaleLabel">
+          <property name="text">
+           <string>Scale</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QSlider" name="accumScale">
+          <property name="minimum">
+           <number>-100</number>
+          </property>
+          <property name="maximum">
+           <number>100</number>
+          </property>
+          <property name="orientation">
+           <enum>Qt::Horizontal</enum>
+          </property>
+         </widget>
+        </item>
+       </layout>
+      </widget>
+     </item>
      <item>
       <spacer name="verticalSpacer">
        <property name="orientation">
@@ -253,6 +302,38 @@
     </hint>
    </hints>
   </connection>
+  <connection>
+   <sender>accumSigma</sender>
+   <signal>valueChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>729</x>
+     <y>479</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>399</x>
+     <y>299</y>
+    </hint>
+   </hints>
+  </connection>
+  <connection>
+   <sender>accumScale</sender>
+   <signal>valueChanged(int)</signal>
+   <receiver>MainWindow</receiver>
+   <slot>updateView()</slot>
+   <hints>
+    <hint type="sourcelabel">
+     <x>729</x>
+     <y>535</y>
+    </hint>
+    <hint type="destinationlabel">
+     <x>399</x>
+     <y>299</y>
+    </hint>
+   </hints>
+  </connection>
  </connections>
  <slots>
   <slot>updateView()</slot>