From e2c9609e0ecd1527eb630c9818327691113cec4a Mon Sep 17 00:00:00 2001
From: jbb01 <32650546+jbb01@users.noreply.github.com>
Date: Thu, 8 Aug 2024 21:10:38 +0200
Subject: [PATCH] add Vec3#fma to improve performance

---
 .../eu/jonahbauer/raytracing/math/Ray.java    |  6 +----
 .../eu/jonahbauer/raytracing/math/Vec3.java   | 22 ++++++++++++++-----
 .../render/camera/SimpleCamera.java           |  2 +-
 .../render/material/MetallicMaterial.java     |  2 +-
 4 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/src/main/java/eu/jonahbauer/raytracing/math/Ray.java b/src/main/java/eu/jonahbauer/raytracing/math/Ray.java
index ca3d79c..c622be1 100644
--- a/src/main/java/eu/jonahbauer/raytracing/math/Ray.java
+++ b/src/main/java/eu/jonahbauer/raytracing/math/Ray.java
@@ -11,11 +11,7 @@ public record Ray(@NotNull Vec3 origin, @NotNull Vec3 direction) {
     }
 
     public @NotNull Vec3 at(double t) {
-        return new Vec3(
-                Math.fma(t, direction.x(), origin.x()),
-                Math.fma(t, direction.y(), origin.y()),
-                Math.fma(t, direction.z(), origin.z())
-        );
+        return Vec3.fma(t, direction, origin);
     }
 
     public int vmask() {
diff --git a/src/main/java/eu/jonahbauer/raytracing/math/Vec3.java b/src/main/java/eu/jonahbauer/raytracing/math/Vec3.java
index 6398560..3bdb046 100644
--- a/src/main/java/eu/jonahbauer/raytracing/math/Vec3.java
+++ b/src/main/java/eu/jonahbauer/raytracing/math/Vec3.java
@@ -5,6 +5,8 @@ import org.jetbrains.annotations.NotNull;
 import java.util.Optional;
 import java.util.random.RandomGenerator;
 
+import static eu.jonahbauer.raytracing.Main.DEBUG;
+
 public record Vec3(double x, double y, double z) {
     public static final Vec3 ZERO = new Vec3(0, 0, 0);
     public static final Vec3 MAX = new Vec3(Double.MAX_VALUE, Double.MAX_VALUE, Double.MAX_VALUE);
@@ -14,7 +16,11 @@ public record Vec3(double x, double y, double z) {
     public static final Vec3 UNIT_Z = new Vec3(0, 0, 1);
 
     public Vec3 {
-        assert Double.isFinite(x) && Double.isFinite(y) && Double.isFinite(z) : "x, y and z must be finite";
+        if (DEBUG) {
+            if (!Double.isFinite(x) || !Double.isFinite(y) || !Double.isFinite(z)) {
+                throw new IllegalArgumentException("x, y and z must be finite");
+            }
+        }
     }
 
     /**
@@ -48,11 +54,7 @@ public record Vec3(double x, double y, double z) {
 
     public static @NotNull Vec3 reflect(@NotNull Vec3 vec, @NotNull Vec3 normal) {
         var factor = - 2 * normal.times(vec);
-        return new Vec3(
-                Math.fma(factor, normal.x(), vec.x()),
-                Math.fma(factor, normal.y(), vec.y()),
-                Math.fma(factor, normal.z(), vec.z())
-        );
+        return Vec3.fma(factor, normal, vec);
     }
 
     public static @NotNull Optional<Vec3> refract(@NotNull Vec3 vec, @NotNull Vec3 normal, double ri) {
@@ -101,6 +103,14 @@ public record Vec3(double x, double y, double z) {
         );
     }
 
+    public static @NotNull Vec3 fma(double a, @NotNull Vec3 b, @NotNull Vec3 c) {
+        return new Vec3(
+                Math.fma(a, b.x(), c.x()),
+                Math.fma(a, b.y(), c.y()),
+                Math.fma(a, b.z(), c.z())
+        );
+    }
+
     public @NotNull Vec3 plus(double x, double y, double z) {
         return new Vec3(this.x + x, this.y + y, this.z + z);
     }
diff --git a/src/main/java/eu/jonahbauer/raytracing/render/camera/SimpleCamera.java b/src/main/java/eu/jonahbauer/raytracing/render/camera/SimpleCamera.java
index a26686e..84f40cd 100644
--- a/src/main/java/eu/jonahbauer/raytracing/render/camera/SimpleCamera.java
+++ b/src/main/java/eu/jonahbauer/raytracing/render/camera/SimpleCamera.java
@@ -60,7 +60,7 @@ public final class SimpleCamera implements Camera {
 
         this.pixel00 = origin.plus(direction.times(builder.focusDistance))
                 .minus(u.times(0.5 * viewportWidth)).minus(v.times(0.5 * viewportHeight))
-                .plus(pixelU.div(2)).plus(pixelV.div(2));
+                .plus(pixelU.times(.5)).plus(pixelV.times(.5));
     }
 
     /**
diff --git a/src/main/java/eu/jonahbauer/raytracing/render/material/MetallicMaterial.java b/src/main/java/eu/jonahbauer/raytracing/render/material/MetallicMaterial.java
index c1a66f4..cdffa63 100644
--- a/src/main/java/eu/jonahbauer/raytracing/render/material/MetallicMaterial.java
+++ b/src/main/java/eu/jonahbauer/raytracing/render/material/MetallicMaterial.java
@@ -25,7 +25,7 @@ public record MetallicMaterial(@NotNull Texture texture, double fuzz) implements
     public @NotNull Optional<ScatterResult> scatter(@NotNull Ray ray, @NotNull HitResult hit, @NotNull RandomGenerator random) {
         var newDirection = Vec3.reflect(ray.direction(), hit.normal());
         if (fuzz > 0) {
-            newDirection = newDirection.unit().plus(Vec3.random(random).times(fuzz));
+            newDirection = Vec3.fma(fuzz, Vec3.random(random), newDirection.unit());
         }
         var attenuation = texture.get(hit);
         return Optional.of(new SpecularScatterResult(attenuation, new Ray(hit.position(), newDirection)));