allow multiple sampling targets in a scene

src/main/java/eu/jonahbauer/raytracing/Examples.java

@@ -51,14 +51,13 @@ public class Examples {
     public static @NotNull Example getSimpleScene(int height) {
         if (height <= 0) height = 675;
         return new Example(
-                new Scene(
+                new Scene(getSkyBox(), List.of(
-                        getSkyBox(),
                         new Sphere(new Vec3(0, -100.5, -1.0), 100.0, new LambertianMaterial(new Color(0.8, 0.8, 0.0))),
                         new Sphere(new Vec3(0, 0, -1.2), 0.5, new LambertianMaterial(new Color(0.1, 0.2, 0.5))),
                         new Sphere(new Vec3(-1.0, 0, -1.2), 0.5, new DielectricMaterial(1.5)),
                         new Sphere(new Vec3(-1.0, 0, -1.2), 0.4, new DielectricMaterial(1 / 1.5)),
                         new Sphere(new Vec3(1.0, 0, -1.2), 0.5, new MetallicMaterial(new Color(0.8, 0.6, 0.2), 0.0))
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height * 16 / 9, height)
                         .build()
@@ -119,14 +118,13 @@ public class Examples {
     public static @NotNull Example getSquares(int height) {
         if (height <= 0) height = 600;
         return new Example(
-                new Scene(
+                new Scene(getSkyBox(), List.of(
-                        getSkyBox(),
                         new Parallelogram(new Vec3(-3, -2, 5), new Vec3(0, 0, -4), new Vec3(0, 4, 0), new LambertianMaterial(new Color(1.0, 0.2, 0.2))),
                         new Parallelogram(new Vec3(-2, -2, 0), new Vec3(4, 0, 0), new Vec3(0, 4, 0), new LambertianMaterial(new Color(0.2, 1.0, 0.2))),
                         new Parallelogram(new Vec3(3, -2, 1), new Vec3(0, 0, 4), new Vec3(0, 4, 0), new LambertianMaterial(new Color(0.2, 0.2, 1.0))),
                         new Parallelogram(new Vec3(-2, 3, 1), new Vec3(4, 0, 0), new Vec3(0, 0, 4), new LambertianMaterial(new Color(1.0, 0.5, 0.0))),
                         new Parallelogram(new Vec3(-2, -3, 5), new Vec3(4, 0, 0), new Vec3(0, 0, -4), new LambertianMaterial(new Color(0.2, 0.8, 0.8)))
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height, height)
                         .withFieldOfView(Math.toRadians(80))
@@ -139,12 +137,12 @@ public class Examples {
     public static @NotNull Example getLight(int height) {
         if (height <= 0) height = 225;
         return new Example(
-                new Scene(
+                new Scene(List.of(
                         new Sphere(new Vec3(0, -1000, 0), 1000, new LambertianMaterial(new Color(0.2, 0.2, 0.2))),
                         new Sphere(new Vec3(0, 2, 0), 2, new LambertianMaterial(new Color(0.2, 0.2, 0.2))),
                         new Parallelogram(new Vec3(3, 1, -2), new Vec3(2, 0, 0), new Vec3(0, 2, 0), new DiffuseLight(new Color(4.0, 4.0, 4.0))),
                         new Sphere(new Vec3(0, 7, 0), 2, new DiffuseLight(new Color(4.0, 4.0, 4.0)))
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height * 16 / 9, height)
                         .withFieldOfView(Math.toRadians(20))
@@ -163,7 +161,7 @@ public class Examples {
         var light = new DiffuseLight(new Color(15.0, 15.0, 15.0));
 
         return new Example(
-                new Scene(
+                new Scene(List.of(
                         new Box(
                                 new AABB(new Vec3(0, 0, 0), new Vec3(555, 555, 555)),
                                 white, white, red, green, white, null
@@ -171,7 +169,7 @@ public class Examples {
                         new Parallelogram(new Vec3(343, 554, 332), new Vec3(-130, 0, 0), new Vec3(0, 0, -105), light),
                         new Box(new Vec3(0, 0, 0), new Vec3(165, 330, 165), white).rotateY(Math.toRadians(15)).translate(new Vec3(265, 0, 295)),
                         new Box(new Vec3(0, 0, 0), new Vec3(165, 165, 165), white).rotateY(Math.toRadians(-18)).translate(new Vec3(130, 0, 65))
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height, height)
                         .withFieldOfView(Math.toRadians(40))
@@ -189,7 +187,7 @@ public class Examples {
         var light = new DiffuseLight(new Color(7.0, 7.0, 7.0));
 
         return new Example(
-                new Scene(
+                new Scene(List.of(
                         new Box(
                                 new AABB(new Vec3(0, 0, 0), new Vec3(555, 555, 555)),
                                 white, white, red, green, white, null
@@ -203,7 +201,7 @@ public class Examples {
                                 new Box(new Vec3(0, 0, 0), new Vec3(165, 165, 165), white).rotateY(Math.toRadians(-18)).translate(new Vec3(130, 0, 65)),
                                 0.01, new IsotropicMaterial(Color.WHITE)
                         )
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height, height)
                         .withFieldOfView(Math.toRadians(40))
@@ -223,19 +221,19 @@ public class Examples {
         var aluminum = new MetallicMaterial(new Color(0.8, 0.85, 0.88));
         var glass = new DielectricMaterial(1.5);
 
+        var room = new Box(
+                new AABB(new Vec3(0, 0, 0), new Vec3(555, 555, 555)),
+                white, white, red, green, white, null
+        );
+        var lamp = new Parallelogram(new Vec3(343, 554, 332), new Vec3(-130, 0, 0), new Vec3(0, 0, -105), light);
+        var box = new Box(
+                new AABB(new Vec3(0, 0, 0), new Vec3(165, 330, 165)),
+                white, white, white, white, white, aluminum
+        ).rotateY(Math.toRadians(15)).translate(new Vec3(265, 0, 295));
+        var sphere = new Sphere(new Vec3(190, 90, 190), 90, glass);
+
         return new Example(
-                new Scene(
+                new Scene(List.of(room, box), List.of(lamp, sphere)),
-                        new Box(
-                                new AABB(new Vec3(0, 0, 0), new Vec3(555, 555, 555)),
-                                white, white, red, green, white, null
-                        ),
-                        new Parallelogram(new Vec3(343, 554, 332), new Vec3(-130, 0, 0), new Vec3(0, 0, -105), light),
-                        new Box(
-                                new AABB(new Vec3(0, 0, 0), new Vec3(165, 330, 165)),
-                                white, white, white, white, white, aluminum
-                        ).rotateY(Math.toRadians(15)).translate(new Vec3(265, 0, 295)),
-                        new Sphere(new Vec3(190, 90, 190), 90, glass)
-                ),
                 SimpleCamera.builder()
                         .withImage(height, height)
                         .withFieldOfView(Math.toRadians(40))
@@ -297,10 +295,9 @@ public class Examples {
         if (height <= 0) height = 450;
 
         return new Example(
-                new Scene(
+                new Scene(getSkyBox(), List.of(
-                        getSkyBox(),
                         new Sphere(Vec3.ZERO, 2, new LambertianMaterial(new ImageTexture("/earthmap.jpg")))
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height * 16 / 9, height)
                         .withFieldOfView(Math.toRadians(20))
@@ -316,11 +313,10 @@ public class Examples {
         var material = new LambertianMaterial(new PerlinTexture(4));
 
         return new Example(
-                new Scene(
+                new Scene(getSkyBox(), List.of(
-                        getSkyBox(),
                         new Sphere(new Vec3(0, -1000, 0), 1000, material),
                         new Sphere(new Vec3(0, 2, 0), 2, material)
-                ),
+                )),
                 SimpleCamera.builder()
                         .withImage(height * 16 / 9, height)
                         .withFieldOfView(Math.toRadians(20))

src/main/java/eu/jonahbauer/raytracing/render/renderer/SimpleRenderer.java

@@ -170,7 +170,7 @@ public final class SimpleRenderer implements Renderer {
                     }
                 }
                 case Material.PdfScatterResult(var a, var pdf) -> {
-                    if (scene.getLights() == null) {
+                    if (scene.getTargets() == null) {
                         attenuation = Color.multiply(attenuation, a);
                         ray = new Ray(hit.position(), pdf.generate(random));
 
@@ -178,7 +178,7 @@ public final class SimpleRenderer implements Renderer {
                             System.out.println("  Pdf scattering with albedo " + a);
                         }
                     } else {
-                        var mixed = new MixtureProbabilityDensityFunction(new TargetingProbabilityDensityFunction(hit.position(), scene.getLights()), pdf, 0.5);
+                        var mixed = new MixtureProbabilityDensityFunction(new TargetingProbabilityDensityFunction(hit.position(), scene.getTargets()), pdf, 0.5);
                         var direction = mixed.generate(random);
 
                         var idealPdf = pdf.value(direction);
@@ -194,7 +194,6 @@ public final class SimpleRenderer implements Renderer {
                             System.out.println("  Pdf scattering with albedo " + a + " and factor " + factor);
                         }
                     }
-
                 }
             }
 

src/main/java/eu/jonahbauer/raytracing/render/renderer/pdf/TargetingProbabilityDensityFunction.java

@@ -4,25 +4,33 @@ import eu.jonahbauer.raytracing.math.Vec3;
 import eu.jonahbauer.raytracing.scene.Target;
 import org.jetbrains.annotations.NotNull;
 
+import java.util.List;
 import java.util.Objects;
 import java.util.random.RandomGenerator;
 
 /**
  * A probability density function targeting a target.
  */
-public record TargetingProbabilityDensityFunction(@NotNull Vec3 origin, @NotNull Target target) implements ProbabilityDensityFunction {
+public record TargetingProbabilityDensityFunction(@NotNull Vec3 origin, @NotNull List<@NotNull Target> targets) implements ProbabilityDensityFunction {
     public TargetingProbabilityDensityFunction {
         Objects.requireNonNull(origin, "origin");
-        Objects.requireNonNull(target, "target");
+        targets = List.copyOf(targets);
     }
 
     @Override
     public double value(@NotNull Vec3 direction) {
-        return target.getProbabilityDensity(origin, direction);
+        var weight = 1d / targets.size();
+        var sum = 0.0;
+
+        for (var target : targets) {
+            sum += weight * target.getProbabilityDensity(origin, direction);
+        }
+
+        return sum;
     }
 
     @Override
     public @NotNull Vec3 generate(@NotNull RandomGenerator random) {
-        return target.getTargetingDirection(origin, random);
+        return targets.get(random.nextInt(targets.size())).getTargetingDirection(origin, random);
     }
 }

src/main/java/eu/jonahbauer/raytracing/render/texture/Color.java

@@ -1,13 +1,15 @@
 package eu.jonahbauer.raytracing.render.texture;
 
+import eu.jonahbauer.raytracing.math.Ray;
 import eu.jonahbauer.raytracing.math.Vec3;
+import eu.jonahbauer.raytracing.scene.SkyBox;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Random;
 
 import static eu.jonahbauer.raytracing.Main.DEBUG;
 
-public record Color(double r, double g, double b) implements Texture {
+public record Color(double r, double g, double b) implements Texture, SkyBox {
     public static final @NotNull Color BLACK = new Color(0.0, 0.0, 0.0);
     public static final @NotNull Color WHITE = new Color(1.0, 1.0, 1.0);
     public static final @NotNull Color RED = new Color(1.0, 0.0, 0.0);
@@ -112,6 +114,11 @@ public record Color(double r, double g, double b) implements Texture {
         return this;
     }
 
+    @Override
+    public @NotNull Color getColor(@NotNull Ray ray) {
+        return this;
+    }
+
     @Override
     public boolean isUVRequired() {
         return false;

src/main/java/eu/jonahbauer/raytracing/scene/Scene.java

@@ -8,6 +8,7 @@ import eu.jonahbauer.raytracing.scene.util.HittableCollection;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 
@@ -15,33 +16,28 @@ public final class Scene extends HittableCollection {
     private final @NotNull HittableCollection objects;
     private final @NotNull SkyBox background;
 
-    private final @Nullable Target light;
+    private final @Nullable List<@NotNull Target> targets;
 
     public Scene(@NotNull List<? extends @NotNull Hittable> objects) {
-        this(Color.BLACK, objects);
+        this(objects, null);
     }
 
-    public Scene(@NotNull Color background, @NotNull List<? extends @NotNull Hittable> objects) {
+    public Scene(@NotNull List<? extends @NotNull Hittable> objects, @Nullable List<? extends @NotNull Target> targets) {
-        this(SkyBox.solid(background), objects);
+        this(Color.BLACK, objects, targets);
     }
 
     public Scene(@NotNull SkyBox background, @NotNull List<? extends @NotNull Hittable> objects) {
-        this.objects = new HittableBinaryTree(objects);
+        this(background, objects, null);
-        this.background = Objects.requireNonNull(background);
-
-        this.light = (Target) objects.get(1);
-    }
-
-    public Scene(@NotNull Hittable @NotNull... objects) {
-        this(List.of(objects));
     }
 
-    public Scene(@NotNull Color background, @NotNull Hittable @NotNull... objects) {
+    public Scene(@NotNull SkyBox background, @NotNull List<? extends @NotNull Hittable> objects, @Nullable List<? extends @NotNull Target> targets) {
-        this(background, List.of(objects));
+        var list = new ArrayList<Hittable>(objects.size() + (targets != null ? targets.size() : 0));
-    }
+        list.addAll(objects);
+        if (targets != null) list.addAll(targets);
+        this.objects = new HittableBinaryTree(list);
+        this.background = Objects.requireNonNull(background);
 
-    public Scene(@NotNull SkyBox background, @NotNull Hittable @NotNull... objects) {
+        this.targets = targets != null ? List.copyOf(targets) : null;
-        this(background, List.of(objects));
     }
 
     @Override
@@ -54,8 +50,8 @@ public final class Scene extends HittableCollection {
         return objects.getBoundingBox();
     }
 
-    public @Nullable Target getLights() {
+    public @Nullable List<@NotNull Target> getTargets() {
-        return light;
+        return targets;
     }
 
     public @NotNull Color getBackgroundColor(@NotNull Ray ray) {

src/main/java/eu/jonahbauer/raytracing/scene/SkyBox.java

@@ -18,8 +18,4 @@ public interface SkyBox {
             return Color.lerp(bottom, top, alt / Math.PI + 0.5);
         };
     }
-
-    static @NotNull SkyBox solid(@NotNull Color color) {
-        return _ -> color;
-    }
 }