improve documentation

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

@@ -130,7 +130,7 @@ public final class SimpleRenderer implements Renderer {
         var attenuation = Color.WHITE;
 
         while (depth-- > 0) {
-            var optional = scene.hit(ray, new Range(0.001, Double.POSITIVE_INFINITY));
+            var optional = scene.hit(ray);
             if (optional.isEmpty()) {
                 var background = scene.getBackgroundColor(ray);
                 color = Color.add(color, Color.multiply(attenuation, background));

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

@@ -5,12 +5,27 @@ import eu.jonahbauer.raytracing.scene.HitResult;
 import org.jetbrains.annotations.NotNull;
 
 public interface Texture {
+    /**
+     * {@return the color of <code>this</code> texture for a hit}
+     */
     default @NotNull Color get(@NotNull HitResult hit) {
         return get(hit.u(), hit.v(), hit.position());
     }
 
+    /**
+     * {@return the color of <code>this</code> texture at the specified position}
+     * @param u the texture u coordinate
+     * @param v the texture v coordinate
+     * @param p the position
+     */
     @NotNull Color get(double u, double v, @NotNull Vec3 p);
 
+    /**
+     * Returns whether {@link #get(double, double, Vec3)} uses the {@code u} and/or {@code v} parameters.
+     * When a texture indicates that the {@code u} and {@code v} coordinates are not required, the calculation may be
+     * skipped and {@link Double#NaN} will be passed.
+     * @return whether {@link #get(double, double, Vec3)} uses the {@code u} and/or {@code v} parameters
+     */
     default boolean isUVRequired() {
         return true;
     }

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

@@ -1,11 +1,25 @@
 package eu.jonahbauer.raytracing.scene;
 
+import eu.jonahbauer.raytracing.math.Range;
+import eu.jonahbauer.raytracing.math.Ray;
 import eu.jonahbauer.raytracing.math.Vec3;
 import eu.jonahbauer.raytracing.render.material.Material;
+import eu.jonahbauer.raytracing.render.texture.Texture;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Objects;
 
+/**
+ * The result of a {@linkplain Hittable#hit(Ray, Range) hit}.
+ * @param t the {@code t} value at which the hit occurs
+ * @param position the position of the hit
+ * @param normal the surface normal at the hit position
+ * @param target the hit target (for debug purposes only)
+ * @param material the material of the surface
+ * @param u the texture u coordinate (or {@code Double.NaN} if the {@linkplain Material#texture() material's texture} does {@linkplain Texture#isUVRequired() not depend} on the uv-coordinates)
+ * @param v the texture v coordinate (or {@code Double.NaN} if the {@linkplain Material#texture() material's texture} does {@linkplain Texture#isUVRequired() not depend} on the uv-coordinates)
+ * @param isFrontFace whether the front or the back of the surface was it
+ */
 public record HitResult(
         double t, @NotNull Vec3 position, @NotNull Vec3 normal, @NotNull Hittable target,
         @NotNull Material material, double u, double v, boolean isFrontFace

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

@@ -13,9 +13,22 @@ import java.util.Optional;
 public interface Hittable {
 
     /**
-     * {@return the value <code>t</code> such that <code>ray.at(t)</code> is the intersection of this shaped closest to
-     * the ray origin, or <code>Double.NaN</code> if the ray does not intersect this shape}
+     * @see #hit(Ray, Range)
+     */
+    default @NotNull Optional<HitResult> hit(@NotNull Ray ray) {
+        return hit(ray, new Range(0.001, Double.POSITIVE_INFINITY));
+    }
+
+    /**
+     * Tests whether the {@code ray} intersects {@code this} hittable.
+     * <p>
+     * The second parameter {@code range} allows the implementation to skip unnecessary calculations if it can
+     * determine that a hit (if any) will fall outside the valid range of {@code t}s. The returned hit may still be
+     * outside the valid range and has to be checked by the caller.
      * @param ray a ray
+     * @param range the range of valid {@code t}s
+     * @return the result of the hit test, containing (among others) the value {@code t} such that {@code ray.at(t)} is
+     *         a point on {@code this} hittable
      */
     @NotNull Optional<HitResult> hit(@NotNull Ray ray, @NotNull Range range);
 

src/main/java/eu/jonahbauer/raytracing/scene/hittable2d/Parallelogram.java

@@ -31,7 +31,7 @@ public final class Parallelogram extends Hittable2D implements Target {
 
     @Override
     public double getProbabilityDensity(@NotNull Vec3 origin, @NotNull Vec3 direction) {
-        var result = hit(new Ray(origin, direction), new Range(0.001, Double.POSITIVE_INFINITY));
+        var result = hit(new Ray(origin, direction));
         if (result.isEmpty()) return 0;
 
         var a = this.origin;

src/main/java/eu/jonahbauer/raytracing/scene/hittable3d/Box.java

@@ -121,7 +121,7 @@ public final class Box implements Hittable, Target {
     @Override
     public double getProbabilityDensity(@NotNull Vec3 origin, @NotNull Vec3 direction) {
         if (contains(origin)) return 1 / (4 * Math.PI);
-        if (hit(new Ray(origin, direction), new Range(0.001, Double.POSITIVE_INFINITY)).isEmpty()) return 0;
+        if (hit(new Ray(origin, direction)).isEmpty()) return 0;
 
         var solidAngle = 0d;
         for (var s : Side.values()) {

src/main/java/eu/jonahbauer/raytracing/scene/hittable3d/Sphere.java

@@ -79,7 +79,7 @@ public final class Sphere implements Hittable, Target {
 
     @Override
     public double getProbabilityDensity(@NotNull Vec3 origin, @NotNull Vec3 direction) {
-        if (hit(new Ray(origin, direction), new Range(0.001, Double.POSITIVE_INFINITY)).isEmpty()) return 0;
+        if (hit(new Ray(origin, direction)).isEmpty()) return 0;
 
         var cos = Math.sqrt(1 - radius * radius / (center.minus(origin).squared()));
         var solidAngle = 2 * Math.PI * (1 - cos);