From f75656ea59bf869afd6ef242caddd890a8247bef Mon Sep 17 00:00:00 2001
From: Erik Hofman <erik@ehofman.com>
Date: Sun, 12 Sep 2010 11:06:14 +0200
Subject: [PATCH] Allow for scenery de-saturation

---
 src/Time/light.cxx | 13 ++++++++++++-
 src/Time/light.hxx |  2 +-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/Time/light.cxx b/src/Time/light.cxx
index 08d0fbf72..24d1c7caf 100644
--- a/src/Time/light.cxx
+++ b/src/Time/light.cxx
@@ -108,6 +108,7 @@ FGLight::FGLight ()
       _cloud_color(0, 0, 0, 0),
       _adj_fog_color(0, 0, 0, 0),
       _adj_sky_color(0, 0, 0, 0),
+      _saturation(1.0),
       _dt_total(0)
 {
 }
@@ -172,6 +173,7 @@ void FGLight::reinit () {
 void FGLight::bind () {
     SGPropertyNode *prop = globals->get_props();
     prop->tie("/sim/time/sun-angle-rad",SGRawValuePointer<double>(&_sun_angle));
+    prop->tie("/rendering/scene/saturation",SGRawValuePointer<float>(&_saturation));
     prop->tie("/rendering/scene/ambient/red",SGRawValuePointer<float>(&_scene_ambient[0]));
     prop->tie("/rendering/scene/ambient/green",SGRawValuePointer<float>(&_scene_ambient[1]));
     prop->tie("/rendering/scene/ambient/blue",SGRawValuePointer<float>(&_scene_ambient[2]));
@@ -201,6 +203,7 @@ void FGLight::bind () {
 void FGLight::unbind () {
     SGPropertyNode *prop = globals->get_props();
     prop->untie("/sim/time/sun-angle-rad");
+    prop->untie("/rendering/scene/saturation");
     prop->untie("/rendering/scene/ambient/red");
     prop->untie("/rendering/scene/ambient/green");
     prop->untie("/rendering/scene/ambient/blue");
@@ -251,11 +254,19 @@ void FGLight::update_sky_color () {
     float deg = _sun_angle * SGD_RADIANS_TO_DEGREES;
     SG_LOG( SG_EVENT, SG_DEBUG, "  Sun angle = " << deg );
 
+    if (_saturation < 0.0) _saturation = 0.0;
+    else if (_saturation > 1.0) _saturation = 1.0;
+
     float ambient = _ambient_tbl->interpolate( deg ) + visibility_inv/10;
     float diffuse = _diffuse_tbl->interpolate( deg );
     float specular = _specular_tbl->interpolate( deg ) * visibility_log;
     float sky_brightness = _sky_tbl->interpolate( deg );
 
+    ambient *= _saturation;
+    diffuse *= _saturation;
+    specular *= _saturation;
+    sky_brightness *= _saturation;
+
     SG_LOG( SG_EVENT, SG_DEBUG,
 	    "  ambient = " << ambient << "  diffuse = " << diffuse 
 	    << "  specular = " << specular << "  sky = " << sky_brightness );
@@ -394,7 +405,7 @@ void FGLight::update_adj_fog_color () {
        sif = 1e-4;
 
     float rf1 = fabs((hor_rotation - SGD_PI) / SGD_PI);		// 0.0 .. 1.0
-    float rf2 = avf * pow(rf1*rf1, 1/sif) * 1.0639;
+    float rf2 = avf * pow(rf1*rf1, 1/sif) * 1.0639 * _saturation;
     float rf3 = 1.0 - rf2;
 
     gamma = system_gamma * (0.9 - sif*avf);
diff --git a/src/Time/light.hxx b/src/Time/light.hxx
index ebc509966..42a9f27d8 100644
--- a/src/Time/light.hxx
+++ b/src/Time/light.hxx
@@ -96,6 +96,7 @@ private:
     // clear sky and fog color adjusted for sunset effects
     SGVec4f _adj_fog_color;
     SGVec4f _adj_sky_color;
+    float _saturation;
 
     double _dt_total;
 
@@ -131,7 +132,6 @@ public:
     inline const SGVec4f& adj_fog_color () const { return _adj_fog_color; }
     inline const SGVec4f& adj_sky_color () const { return _adj_sky_color; }
 
-
     // Sun related functions
 
     inline double get_sun_angle () const { return _sun_angle; }
-- 
2.39.5