From 3b76969ff2f19e6979a1fcb5a335a63aaaa7ed50 Mon Sep 17 00:00:00 2001
From: Maximilian Giller <m.giller.dev@gmail.com>
Date: Tue, 24 Jan 2023 19:59:13 +0100
Subject: [PATCH] Colored refraction shader

---
 shader/refractionshader.cpp | 95 ++++++++++++++++++++-----------------
 shader/refractionshader.h   | 19 ++++----
 2 files changed, 63 insertions(+), 51 deletions(-)

diff --git a/shader/refractionshader.cpp b/shader/refractionshader.cpp
index 80d2124..e13916a 100644
--- a/shader/refractionshader.cpp
+++ b/shader/refractionshader.cpp
@@ -1,51 +1,60 @@
 #include "scene/scene.h"
 #include "shader/refractionshader.h"
 
-RefractionShader::RefractionShader(float indexInside, float indexOutside) : indexInside(indexInside), indexOutside(indexOutside) {}
+RefractionShader::RefractionShader(float indexInside, float indexOutside, Color const &objectColor) : indexInside(
+        indexInside), indexOutside(indexOutside), objectColor(objectColor)
+{}
 
-Color RefractionShader::shade(Scene const &scene, Ray const &ray) const {
-  // Circumvent getting environment map color into the mix
-  if (ray.getRemainingBounces() > 0) {
-    // Get the normal of the primitive which was hit
-    Vector3d normalVector = ray.normal;
+Color RefractionShader::shade(Scene const &scene, Ray const &ray) const
+{
+    // Circumvent getting environment map color into the mix
+    if (ray.getRemainingBounces() > 0)
+    {
+        // Get the normal of the primitive which was hit
+        Vector3d normalVector = ray.normal;
 
-    // Calculate the index of refraction
-    float refractiveIndex = indexOutside / indexInside;
-    // What if we are already inside the object?
-    if (dotProduct(normalVector, ray.direction) > 0) {
-      normalVector = -normalVector;
-      refractiveIndex = indexInside / indexOutside;
+        // Calculate the index of refraction
+        float refractiveIndex = indexOutside / indexInside;
+        // What if we are already inside the object?
+        if (dotProduct(normalVector, ray.direction) > 0)
+        {
+            normalVector = -normalVector;
+            refractiveIndex = indexInside / indexOutside;
+        }
+
+        // Using the notation from the lecture
+        float cosineTheta = dotProduct(normalVector, -ray.direction);
+        float cosinePhi = std::sqrt(1 + refractiveIndex * refractiveIndex * (cosineTheta * cosineTheta - 1));
+        // Calculate t, the new ray direction
+        Vector3d t = refractiveIndex * ray.direction + (refractiveIndex * cosineTheta - cosinePhi) * normalVector;
+
+        // Create the refraction ray
+        Ray refractionRay = ray;
+        // Reset the ray
+        refractionRay.length = INFINITY;
+        refractionRay.primitive = nullptr;
+
+        // Check whether it is a refraction.
+        if (dotProduct(t, normalVector) <= 0.0)
+        {
+            refractionRay.origin = ray.origin + (ray.length + REFR_EPS) * ray.direction;
+            refractionRay.direction = normalized(t);
+        } else
+        { // Otherwise, it is a total reflection.
+            refractionRay.origin = ray.origin + (ray.length - REFR_EPS) * ray.direction;
+            // Next we get the reflection vector
+            Vector3d const reflectionVector =
+                    ray.direction - 2.0f * dotProduct(normalVector, ray.direction) * normalVector;
+
+            // Change the ray direction and origin
+            refractionRay.direction = normalized(reflectionVector);
+        }
+
+        // Send out a new refracted ray into the scene
+        return scene.traceRay(refractionRay) * objectColor;
     }
-
-    // Using the notation from the lecture
-    float cosineTheta = dotProduct(normalVector, -ray.direction);
-    float cosinePhi = std::sqrt(1 + refractiveIndex * refractiveIndex * (cosineTheta * cosineTheta - 1));
-    // Calculate t, the new ray direction
-    Vector3d t = refractiveIndex * ray.direction + (refractiveIndex * cosineTheta - cosinePhi) * normalVector;
-
-    // Create the refraction ray
-    Ray refractionRay = ray;
-    // Reset the ray
-    refractionRay.length = INFINITY;
-    refractionRay.primitive = nullptr;
-
-    // Check whether it is a refraction.
-    if (dotProduct(t, normalVector) <= 0.0) {
-      refractionRay.origin = ray.origin + (ray.length + REFR_EPS) * ray.direction;
-      refractionRay.direction = normalized(t);
-    } else { // Otherwise, it is a total reflection.
-      refractionRay.origin = ray.origin + (ray.length - REFR_EPS) * ray.direction;
-      // Next we get the reflection vector
-      Vector3d const reflectionVector = ray.direction - 2.0f * dotProduct(normalVector, ray.direction) * normalVector;
-
-      // Change the ray direction and origin
-      refractionRay.direction = normalized(reflectionVector);
-    }
-
-    // Send out a new refracted ray into the scene
-    return scene.traceRay(refractionRay);
-  }
-  return Color(0.0f, 0.0f, 0.0f);
+    return Color(0.0f, 0.0f, 0.0f);
 }
 
-bool RefractionShader::isTransparent() const { return true; }
+bool RefractionShader::isTransparent() const
+{ return true; }
diff --git a/shader/refractionshader.h b/shader/refractionshader.h
index 5c1043e..7b489da 100644
--- a/shader/refractionshader.h
+++ b/shader/refractionshader.h
@@ -3,19 +3,22 @@
 
 #include "shader/shader.h"
 
-class RefractionShader : public Shader {
+class RefractionShader : public Shader
+{
 
 public:
-  // Constructor
-  RefractionShader(float indexInside, float indexOutside);
+    // Constructor
+    RefractionShader(float indexInside, float indexOutside, Color const &objectColor = Color(1, 1, 1));
 
-  // Shader functions
-  Color shade(Scene const &scene, Ray const &ray) const override;
-  bool isTransparent() const override;
+    // Shader functions
+    Color shade(Scene const &scene, Ray const &ray) const override;
+
+    bool isTransparent() const override;
 
 private:
-  float indexInside;
-  float indexOutside;
+    float indexInside;
+    float indexOutside;
+    Color objectColor;
 };
 
 #endif