add light sources

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

@@ -12,6 +12,7 @@ import eu.jonahbauer.raytracing.render.renderer.SimpleRenderer;
 import eu.jonahbauer.raytracing.scene.*;
 import eu.jonahbauer.raytracing.scene.hittable2d.Parallelogram;
 import eu.jonahbauer.raytracing.scene.hittable3d.Sphere;
+import eu.jonahbauer.raytracing.scene.util.Hittables;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.IOException;
@@ -22,12 +23,12 @@ import java.util.Random;
 
 public class Main {
     public static void main(String[] args) throws IOException {
-        var example = getSquares();
+        var example = getLight();
         var scene = example.scene();
         var camera = example.camera();
 
         var renderer = SimpleRenderer.builder()
-                .withSamplesPerPixel(500)
+                .withSamplesPerPixel(1000)
                 .withMaxDepth(50)
                 .withIterative(true)
                 .build();
@@ -107,6 +108,23 @@ public class Main {
         );
     }
 
+    private static @NotNull Example getLight() {
+        return new Example(
+                new Scene(
+                        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(400, 225)
+                        .withFieldOfView(Math.toRadians(20))
+                        .withPosition(new Vec3(26, 3, 6))
+                        .withTarget(new Vec3(0, 2, 0))
+                        .build()
+        );
+    }
+
     private static @NotNull Scene getSimpleScene() {
         return new Scene(
                 getSkyBox(),

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

@@ -25,6 +25,10 @@ public record Color(double r, double g, double b) {
         return new Color(a.r() * b.r(), a.g() * b.g(), a.b() * b.b());
     }
 
+    public static @NotNull Color add(@NotNull Color a, @NotNull Color b) {
+        return new Color(a.r() + b.r(), a.g() + b.g(), a.b() + b.b());
+    }
+
     public static @NotNull Color random(@NotNull Random random) {
         return new Color(random.nextDouble(), random.nextDouble(), random.nextDouble());
     }

src/main/java/eu/jonahbauer/raytracing/render/material/DiffuseLight.java

@@ -0,0 +1,20 @@
+package eu.jonahbauer.raytracing.render.material;
+
+import eu.jonahbauer.raytracing.math.Ray;
+import eu.jonahbauer.raytracing.render.Color;
+import eu.jonahbauer.raytracing.scene.HitResult;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Optional;
+
+public record DiffuseLight(@NotNull Color emit) implements Material {
+    @Override
+    public @NotNull Optional<ScatterResult> scatter(@NotNull Ray ray, @NotNull HitResult hit) {
+        return Optional.empty();
+    }
+
+    @Override
+    public @NotNull Color emitted(@NotNull HitResult hit) {
+        return emit;
+    }
+}

src/main/java/eu/jonahbauer/raytracing/render/material/Material.java

@@ -12,6 +12,10 @@ public interface Material {
 
     @NotNull Optional<ScatterResult> scatter(@NotNull Ray ray, @NotNull HitResult hit);
 
+    default @NotNull Color emitted(@NotNull HitResult hit) {
+        return Color.BLACK;
+    }
+
     record ScatterResult(@NotNull Ray ray, @NotNull Color attenuation) {
         public ScatterResult {
             Objects.requireNonNull(ray, "ray");

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

@@ -92,9 +92,11 @@ public final class SimpleRenderer implements Renderer {
         if (optional.isPresent()) {
             var hit = optional.get();
             var material = hit.material();
+            var emitted = material.emitted(hit);
             return material.scatter(ray, hit)
                     .map(scatter -> Color.multiply(scatter.attenuation(), getColor0(scene, scatter.ray(), depth - 1)))
-                    .orElse(Color.BLACK);
+                    .map(color -> Color.add(color, emitted))
+                    .orElse(emitted);
         } else {
             return scene.getBackgroundColor(ray);
         }