From d7d38944ea254d9e0bb0b4e0eb732fd796cb9cd8 Mon Sep 17 00:00:00 2001
From: Maximilian Giller <m.giller.dev@gmail.com>
Date: Tue, 24 Jan 2023 11:31:09 +0100
Subject: [PATCH] Implements SunLight

---
 fancy1.cpp         |  3 ++-
 light/sunlight.cpp | 31 +++++++++++++++++++++++++++++++
 light/sunlight.h   | 20 ++++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 light/sunlight.cpp
 create mode 100644 light/sunlight.h

diff --git a/fancy1.cpp b/fancy1.cpp
index a5534c7..ffd0801 100644
--- a/fancy1.cpp
+++ b/fancy1.cpp
@@ -21,6 +21,7 @@
 #include "common/noise/perlinnoise.h"
 #include "shader/noiseshader.h"
 #include "common/noise/cloudnoise.h"
+#include "light/sunlight.h"
 
 int main()
 {
@@ -28,7 +29,7 @@ int main()
     scene.setBackgroundColor(Color(0.529f, 0.808f, 0.922f));
 
     // Add lights
-    auto mainLight = std::make_shared<PointLight>(Vector3d(5.0f, 10.0f, 0.0f), 100.0f);
+    auto mainLight = std::make_shared<SunLight>(Vector3d(1.0f, -1.0f, -1.0f), 10.0f);
     scene.add(mainLight);
     scene.add(std::make_shared<AmbientLight>(0.3f));
 
diff --git a/light/sunlight.cpp b/light/sunlight.cpp
new file mode 100644
index 0000000..dc355fb
--- /dev/null
+++ b/light/sunlight.cpp
@@ -0,0 +1,31 @@
+#include "sunlight.h"
+
+
+SunLight::SunLight(Vector3d const &direction, float intensity, Color const &color) : Light(intensity, color),
+                                                                                     direction(normalized(direction))
+{}
+
+Light::Illumination SunLight::illuminate(Scene const &scene, Ray const &ray) const
+{
+    Vector3d const target = ray.origin + (ray.length - LGT_EPS) * ray.direction;
+
+    // Illumination object
+    Illumination illum;
+    illum.direction = this->direction;
+
+    // Define a secondary ray from the surface point to the light source.
+    Ray lightRay;
+    lightRay.origin = target;
+    lightRay.direction = -illum.direction;
+    lightRay.length = INFINITY;
+
+    // If the target is not in shadow...
+    if (!scene.findOcclusion(lightRay))
+    {
+        // Look at angleIntensity of light
+        float angleIntensity = dotProduct(-ray.normal,
+                                          this->direction);  // 0 if light is behind surface, 1 if light is in front of surface
+        illum.color = this->color * this->intensity * angleIntensity;
+    }
+    return illum;
+}
\ No newline at end of file
diff --git a/light/sunlight.h b/light/sunlight.h
new file mode 100644
index 0000000..56a5ef9
--- /dev/null
+++ b/light/sunlight.h
@@ -0,0 +1,20 @@
+#ifndef CG1_TRACER_SUNLIGHT_H
+#define CG1_TRACER_SUNLIGHT_H
+
+#include "scene/scene.h"
+#include "light.h"
+
+class SunLight : public Light
+{
+public:
+    SunLight(Vector3d const &direction, float intensity, Color const &color = Color(1, 1, 1));
+
+    // Light functions
+    Illumination illuminate(Scene const &scene, Ray const &ray) const override;
+
+protected:
+    Vector3d direction;
+};
+
+
+#endif //CG1_TRACER_SUNLIGHT_H