Sample multiple lights.

resources/shader/compute-sample.wgsl

@@ -163,24 +163,27 @@ fn sample_direction(hit: HitInfo) -> vec3f {
 }
 
 fn sample_from_light(hit: HitInfo) -> vec3f {
-  // FIXME: 境界が目立つ
   // ヒット位置とライト位置を比較
-  var dist = distance(hit.pos, sphere_lights.l1.center);
-  var sphere = sphere_lights.l1;
+  // FIXME: ライトの個数分追加が必要
+  var l1_dist = distance(hit.pos, sphere_lights.l1.center);
   let l2_dist = distance(hit.pos, sphere_lights.l2.center);
   let l3_dist = distance(hit.pos, sphere_lights.l3.center);
   let l4_dist = distance(hit.pos, sphere_lights.l4.center);
-  if (l2_dist < dist) {
-    dist = l2_dist;
-    sphere = sphere_lights.l2;
+  let l1_w = 1.0 / (l1_dist * l1_dist);
+  let l2_w = 1.0 / (l2_dist * l2_dist);
+  let l3_w = 1.0 / (l3_dist * l3_dist);
+  let l4_w = 1.0 / (l4_dist * l4_dist);
+  let sum = l1_w + l2_w + l3_w + l4_w;
+  let rand = rand();
+  var sphere = sphere_lights.l1;
+  if (l1_w / sum < rand && rand <= (l1_w + l2_w) / sum) {
+      sphere = sphere_lights.l2;
   }
-  if (l3_dist < dist) {
-    dist = l3_dist;
-    sphere = sphere_lights.l3;
+  if ((l1_w + l2_w) / sum < rand && rand <= (l1_w + l2_w + l3_w) / sum) {
+      sphere = sphere_lights.l3;
   }
-  if (l4_dist < dist) {
-    dist = l4_dist;
-    sphere = sphere_lights.l4;
+  if ((l1_w + l2_w + l3_w) / sum < rand && rand <= 1.0) {
+      sphere = sphere_lights.l4;
   }
   return sample_from_sphere(sphere, hit.pos);
 }
@@ -214,21 +217,21 @@ fn sample_from_cosine(hit: HitInfo) -> vec3f {
 }
 
 fn mixture_pdf(hit: HitInfo, dir: vec3f) -> f32 {
-  /// FIXME: 暗くなってしまう
-  let l1_dist = distance(hit.pos, sphere_lights.l1.center);
+  // FIXME: ライトの個数分追加が必要
+  var l1_dist = distance(hit.pos, sphere_lights.l1.center);
   let l2_dist = distance(hit.pos, sphere_lights.l2.center);
   let l3_dist = distance(hit.pos, sphere_lights.l3.center);
   let l4_dist = distance(hit.pos, sphere_lights.l4.center);
-  let dist_sum = l1_dist + l2_dist + l3_dist + l4_dist;
-  let l1_w = (l2_dist + l3_dist + l4_dist) / dist_sum;
-  let l2_w = (l1_dist + l3_dist + l4_dist) / dist_sum;
-  let l3_w = (l1_dist + l2_dist + l4_dist) / dist_sum;
-  let l4_w = (l1_dist + l2_dist + l3_dist) / dist_sum;
+  let l1_w = 1.0 / (l1_dist * l1_dist);
+  let l2_w = 1.0 / (l2_dist * l2_dist);
+  let l3_w = 1.0 / (l3_dist * l3_dist);
+  let l4_w = 1.0 / (l4_dist * l4_dist);
+  let sum = l1_w + l2_w + l3_w + l4_w;
   let light_pdf = l1_w * sphere_pdf(hit, sphere_lights.l1, dir) +
                   l2_w * sphere_pdf(hit, sphere_lights.l2, dir) +
                   l3_w * sphere_pdf(hit, sphere_lights.l3, dir) +
                   l4_w * sphere_pdf(hit, sphere_lights.l4, dir);
-  return 0.5 * cosine_pdf(hit, dir) + 0.5 * light_pdf;
+  return 0.5 * cosine_pdf(hit, dir) + 0.5 * light_pdf / sum;
 }
 
 fn sphere_pdf(hit: HitInfo, sphere: Sphere, dir: vec3f) -> f32 {
@@ -284,7 +287,6 @@ fn raytrace(path: Path, depth: i32) -> Path {
     if (depth == 0) {
       var light_col = hit.col / length(hit.col);
       let dist = distance(camera.start.xyz, hit.pos.xyz);
-      light_col = hit.col / max(dist * dist, 1.0);
       return Path(r, light_col, true);
     }
     // 照明計算
@@ -296,8 +298,6 @@ fn raytrace(path: Path, depth: i32) -> Path {
     // 反射
     let scatter_dir = sample_direction(hit);
     let pdf_val = mixture_pdf(hit, scatter_dir);
-//    let scatter_dir = sample_from_cosine(hit);
-//    let pdf_val = cosine_pdf(hit, scatter_dir);
     // パスを更新
     let scattered_ray = Ray(hit.pos, scatter_dir);
     let scattered_col = path.col * hit.col * scattering_pdf(hit, scatter_dir) / pdf_val;

src/camera.cpp

@@ -60,11 +60,14 @@ void Camera::InitBindGroup(Device &device) {
 }
 
 void Camera::Update(Queue &queue, float t, float aspect) {
-  t = EaseInOutExpo(t);
-  float move_dist = Lerp(0.0, 40.0, t);
-  float fovy = t < 0.5 ? Lerp(40, 90, t / 0.5f) : Lerp(90, 40, (t - 0.5f) / 0.5f);
+  // カメラ: [前半]InQuart, [後半]等速
+  float move_dist = t < 0.2f ? 8.0f * EaseInQuart(t / 0.2f) : 8.0f * EaseInQuart((t - 0.2f) / 0.8f + 1.0f);
   Point3 origin = Vec3(0, 0, 0.01f - move_dist);
   Point3 target = Vec3(0, 0, 15 + move_dist);
+  // fovy変化: 増加は 0.0 ~ 0.15, 減少は 0.95 ~ 1.0
+  float fovy_add_t = t / 0.15f;
+  float fovy_dec_t = (t - 0.95f) / 0.05f;
+  float fovy = t < 0.15f ? Lerp(40, 65, fovy_add_t) : t < 0.95f ? 65 : Lerp(65, 40, EaseOutCubic(fovy_dec_t));
   float time = 0.0f;
   CameraParam param(origin, target, aspect, fovy, time, RandSeed());
   queue.writeBuffer(uniform_buffer_, 0, &param, sizeof(CameraParam));

src/include/utils/util.h

@@ -26,7 +26,7 @@ inline double Deg2Rad(double degrees) {
   return degrees * M_PI * 0.00555555555;
 }
 
-inline double Clamp(double x, double min, double max) {
+inline float Clamp(float x, float min, float max) {
   if (x < min) return min;
   if (x > max) return max;
   return x;
@@ -67,9 +67,17 @@ inline float EaseInQuart(float t) {
   return t * t * t * t;
 }
 
+inline float EaseOutCubic(float t) {
+  return 1.0f - (1.0f - t) * (1.0f - t) * (1.0f - t);
+}
+
 inline float EaseInOutExpo(float t) {
   if (t == 0 || t == 1) {
     return t;
   }
   return t < 0.5 ? pow(2.0f, 20.0f * t - 10.0f) / 2.0f : (2.0f - pow(2.0f, -20.0f * t + 10.0f)) / 2.0f;
+}
+
+inline float Sigmoid(float t) {
+  return 3.0f * t * t - 2.0f * t * t * t;
 }

src/scene.cpp

@@ -11,14 +11,21 @@
  */
 Scene::Scene(Device &device) {
   /// Quadの追加
-  auto pos = Point3(0, 0, -9);
-  auto scale = Vec3(8, 5, 100);
+  auto pos = Point3(0, 0, 0);
+  auto scale = Vec3(8, 5, 500);
   auto cb = CornellBox(pos, scale);
   /// CornellBoxの追加
   cb.PushToQuads(quads_);
 
   /// Sphereの追加
   spheres_.emplace_back(Point3(-1.0, 0, -9), 0.3, Color3(0.8, 0.8, 0.8));
+  // TODO: 光源に変更
+  //　最終位置
+  float end_pos = 128;
+  spheres_.emplace_back(Point3(0.0, 2.0, -(30 + end_pos)), 0.3, Color3(0.8, 0.8, 0.8));
+  spheres_.emplace_back(Point3(0.0, 2.0, -(60 + end_pos)), 0.3, Color3(0.8, 0.8, 0.8));
+  spheres_.emplace_back(Point3(0.0, 2.0, -(90 + end_pos)), 0.3, Color3(0.8, 0.8, 0.8));
+  spheres_.emplace_back(Point3(0.0, 2.0, -(120 + end_pos)), 0.3, Color3(0.8, 0.8, 0.8));
   /// バッファのバインド
   InitBindGroupLayout(device);
   InitBuffers(device);
@@ -328,10 +335,10 @@ void Scene::InitBindGroup(Device &device) {
  * SphereLightの更新
  */
 void Scene::UpdateSphereLights(Queue &queue, float t) {
-  Sphere l1(Point3(0, 0, -50), 0.5, Color3(2000, 2000, 2000), true);
-  Sphere l2(Point3(1.0, 2.0, -10), 0.3, Color3(20, 1500, 20), true);
-  Sphere l3(Point3(0.0, 2.0, -20), 0.3, Color3(1500, 20, 20), true);
-  Sphere l4(Point3(-1.0, 2.0, -30), 0.3, Color3(20, 20, 1500), true);
+  Sphere l1(Point3(0.0, 2.0, -120), 0.3, Color3(500, 500, 500), true);
+  Sphere l2(Point3(0.0, 2.0, -30), 0.3, Color3(2, 150, 2), true);
+  Sphere l3(Point3(0.0, 2.0, -60), 0.3, Color3(150, 2, 2), true);
+  Sphere l4(Point3(0.0, 2.0, -90), 0.3, Color3(2, 2, 150), true);
   SphereLights lights(l1, l2, l3, l4);
   queue.writeBuffer(sphere_light_buffer_, 0, &lights, sizeof(SphereLights));
 }