From 0f9e88ccf0510ab4d830529fa539ef6db715f988 Mon Sep 17 00:00:00 2001
From: Julian T <julian@jtle.dk>
Date: Wed, 16 Sep 2020 20:52:12 +0200
Subject: Added first draft of spectral lightning

---
 src/object.cpp | 19 ++++++++++++++++---
 src/object.hpp |  6 ++++--
 src/render.cpp |  2 +-
 3 files changed, 21 insertions(+), 6 deletions(-)

(limited to 'src')

diff --git a/src/object.cpp b/src/object.cpp
index 1449cbb..15fc267 100644
--- a/src/object.cpp
+++ b/src/object.cpp
@@ -10,15 +10,28 @@ void Color::clamp() {
     if (m_z > 1) { m_z = 1; }
 }
 
-Material::Material(Color color, double defuse, double emissive) {
+Material::Material(Color color, double defuse, double spectral, double spectral_pow, double emissive) {
     m_color = color;
     m_defuse = defuse;
     m_emissive = emissive;
+    m_spectral = spectral;
+    m_spectral_pow = spectral_pow;
 }
 
 Color Material::reflect(const Vec3d &normal, const Vec3d &in, const Vec3d &out, const Color &incol) const {
-    return Vec3d(m_color) * m_emissive + 
-         (Vec3d(m_color) * Vec3d(incol)) * (out.dot(normal) * m_defuse);
+    // Emissive
+    Color c = Vec3d(m_color) * m_emissive;
+
+    // Defuse
+    c += (Vec3d(m_color) * Vec3d(incol)) * (in.dot(normal) * m_defuse);
+
+    // Spectral
+    if (m_spectral > 0) {
+        auto R = normal * (2 * normal.dot(in)) - in;
+        c += Vec3d(incol) * pow(out.dot(R) * m_spectral, m_spectral_pow);
+    }
+
+    return c;
 }
 
 Sphere::Sphere(const Material &mat, Vec3d center, double radius) : Shape(mat) {
diff --git a/src/object.hpp b/src/object.hpp
index e697ba2..3b108fb 100644
--- a/src/object.hpp
+++ b/src/object.hpp
@@ -25,7 +25,7 @@ class Color : public Vec3d {
 // Implements phong BRDF 
 class Material {
     public:
-        Material(Color color, double defuse, double emissive=0);
+        Material(Color color, double defuse, double spectral=0, double spectral_pow=0, double emissive=0);
 
         Color reflect(const Vec3d &normal, const Vec3d &in, const Vec3d &out, const Color &incol) const;
 
@@ -34,11 +34,13 @@ class Material {
         }
 
         // Whether the material is reflective
-        bool reflects() const { return m_defuse > 0; }
+        bool reflects() const { return m_defuse+m_spectral > 0; }
     private:
         Color m_color;
         double m_defuse;
         double m_emissive;
+        double m_spectral;
+        double m_spectral_pow;
 };
 
 class Shape {
diff --git a/src/render.cpp b/src/render.cpp
index c278797..3f2280d 100644
--- a/src/render.cpp
+++ b/src/render.cpp
@@ -124,7 +124,7 @@ Color Renderer::pathtrace_sample(const Ray &r, unsigned hop) {
         auto newray = Ray(end, randdir, true);
         auto incol = pathtrace_sample(newray, hop+1);
 
-        col += res->m_mat.reflect(norm, r.m_direction, newray.m_direction, incol);
+        col += res->m_mat.reflect(norm, newray.m_direction, r.m_direction, incol);
     }
 
     return col;
-- 
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