From 3786b21e1574dd546c0fe15860c935603cb2fdb5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C3=ABl=20Lemaire?= <michael@thunderk.net>
Date: Thu, 26 Dec 2013 17:30:22 +0100
Subject: [PATCH] Added stars to night sky

---
 src/definition/AtmosphereDefinition.cpp | 48 +++++++++++++++++++++++++
 src/definition/AtmosphereDefinition.h   | 12 +++++++
 src/render/software/NightSky.cpp        | 20 +++++++++++
 3 files changed, 80 insertions(+)

diff --git a/src/definition/AtmosphereDefinition.cpp b/src/definition/AtmosphereDefinition.cpp
index 50c22d9..d1fd3c5 100644
--- a/src/definition/AtmosphereDefinition.cpp
+++ b/src/definition/AtmosphereDefinition.cpp
@@ -1,6 +1,7 @@
 #include "AtmosphereDefinition.h"
 
 #include "PackStream.h"
+#include "RandomGenerator.h"
 
 AtmosphereDefinition::AtmosphereDefinition(BaseDefinition* parent):
     BaseDefinition(parent)
@@ -23,6 +24,15 @@ void AtmosphereDefinition::save(PackStream* stream) const
     stream->write(&moon_radius);
     stream->write(&moon_theta);
     stream->write(&moon_phi);
+
+    int star_count = stars.size();
+    stream->write(&star_count);
+    for (const auto &star : stars)
+    {
+        star.location.save(stream);
+        star.col.save(stream);
+        stream->write(&star.radius);
+    }
 }
 
 void AtmosphereDefinition::load(PackStream* stream)
@@ -38,6 +48,19 @@ void AtmosphereDefinition::load(PackStream* stream)
     stream->read(&moon_theta);
     stream->read(&moon_phi);
 
+    int star_count;
+    stream->read(&star_count);
+    for (int i = 0; i < star_count; i++)
+    {
+        Star star;
+
+        star.location.load(stream);
+        star.col.load(stream);
+        stream->read(&star.radius);
+
+        stars.push_back(star);
+    }
+
     validate();
 }
 
@@ -55,6 +78,7 @@ void AtmosphereDefinition::copy(BaseDefinition* _destination) const
     destination->moon_radius = moon_radius;
     destination->moon_theta = moon_theta;
     destination->moon_phi = moon_phi;
+    destination->stars = stars;
 
     destination->validate();
 }
@@ -130,5 +154,29 @@ void AtmosphereDefinition::applyPreset(AtmospherePreset preset)
             ;
     }
 
+    generateStars(5000);
+
     validate();
 }
+
+void AtmosphereDefinition::generateStars(int count)
+{
+    stars.clear();
+
+    for (int i = 0; i < count; ++i)
+    {
+        Star star;
+
+        star.location = Vector3((RandomGenerator::random() - 0.5) * 100000.0, (RandomGenerator::random() - 0.5) * 100000.0, (RandomGenerator::random() - 0.5) * 100000.0);
+        if (star.location.getNorm() < 30000.0)
+        {
+            i--;
+            continue;
+        }
+        double brillance = RandomGenerator::random() * 0.05 + 0.1;
+        star.col = Color(brillance + RandomGenerator::random() * 0.03, brillance + RandomGenerator::random() * 0.03, brillance + RandomGenerator::random() * 0.03, 1.0);
+        star.radius = 30.0 + RandomGenerator::random() * 20.0;
+
+        stars.push_back(star);
+    }
+}
diff --git a/src/definition/AtmosphereDefinition.h b/src/definition/AtmosphereDefinition.h
index 19d1a0b..39d4838 100644
--- a/src/definition/AtmosphereDefinition.h
+++ b/src/definition/AtmosphereDefinition.h
@@ -5,6 +5,7 @@
 
 #include "BaseDefinition.h"
 
+#include "Vector3.h"
 #include "Color.h"
 
 namespace paysages {
@@ -12,6 +13,14 @@ namespace definition {
 
 class AtmosphereDefinition : public BaseDefinition
 {
+public:
+    typedef struct
+    {
+        Vector3 location;
+        double radius;
+        Color col;
+    } Star;
+
 public:
     typedef enum
     {
@@ -38,6 +47,7 @@ public:
     virtual void validate() override;
 
     void applyPreset(AtmospherePreset preset);
+    void generateStars(int count);
 
 public:
     AtmosphereModel model;
@@ -53,6 +63,8 @@ public:
     double moon_phi;
 
     double _daytime;
+
+    std::vector<Star> stars;
 };
 
 }
diff --git a/src/render/software/NightSky.cpp b/src/render/software/NightSky.cpp
index dc6cd3e..1ba1a7b 100644
--- a/src/render/software/NightSky.cpp
+++ b/src/render/software/NightSky.cpp
@@ -35,6 +35,26 @@ const Color NightSky::getColor(double altitude, const Vector3 &direction)
     Vector3 location(0.0, altitude, 0.0);
 
     // Get stars
+    for (const auto &star: atmosphere->stars)
+    {
+        if (star.location.dotProduct(direction) >= 0)
+        {
+            double radius = star.radius;
+            Vector3 hit1, hit2;
+            int hits = Geometry::rayIntersectSphere(location, direction, star.location, radius, &hit1, &hit2);
+            if (hits > 1)
+            {
+                double dist = hit2.sub(hit1).getNorm() / radius; // distance between intersection points (relative to radius)
+
+                Color color = star.col;
+                if (dist <= 0.5)
+                {
+                    color.a *= 1.0 - dist / 0.5;
+                }
+                result.mask(color);
+            }
+        }
+    }
 
     // Get moon
     VectorSpherical moon_location_s = {MOON_DISTANCE_SCALED, atmosphere->moon_theta, -atmosphere->moon_phi};