From c11ac7295c0edc453fef8dd24ba76595c4f0edf2 Mon Sep 17 00:00:00 2001
From: Thorsten Renk <thorsten.i.renk@jyu.fi>
Date: Thu, 17 Oct 2013 11:09:42 +0300
Subject: [PATCH] Fogline blur effect for Atmospheric Light Scattering
 high-detail shader

---
 Effects/tree.eff                | 11 +++++++
 Shaders/terrain-haze-ultra.frag | 16 +++++++++
 Shaders/tree-haze.frag          | 57 +++++++++++++++++++++++++++++++--
 3 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/Effects/tree.eff b/Effects/tree.eff
index a458b2e26..13778e45d 100644
--- a/Effects/tree.eff
+++ b/Effects/tree.eff
@@ -33,6 +33,7 @@
 		<fogtype><use>/sim/rendering/shaders/skydome</use></fogtype>
 		<fogstructure><use>/environment/fog-structure</use></fogstructure>
 		<quality_level><use>/sim/rendering/shaders/landmass</use></quality_level>
+		<tquality_level><use>/sim/rendering/shaders/transition</use></tquality_level>
 		<wind_effects><use>/sim/rendering/shaders/wind-effects</use></wind_effects>
 		<windE><use>/environment/sea/surface/wind-from-east-fps</use></windE>
 		<windN><use>/environment/sea/surface/wind-from-north-fps</use></windN>
@@ -163,6 +164,11 @@
       <type>int</type>
       <value><use>quality_level</use></value>
      </uniform>
+     <uniform>
+      <name>tquality_level</name>
+      <type>int</type>
+      <value><use>tquality_level</use></value>
+     </uniform>
      <uniform>
       <name>wind_effects</name>
       <type>int</type>
@@ -300,6 +306,11 @@
       <type>int</type>
       <value><use>quality_level</use></value>
      </uniform>
+     <uniform>
+      <name>tquality_level</name>
+      <type>int</type>
+      <value><use>tquality_level</use></value>
+     </uniform>
      <uniform>
       <name>wind_effects</name>
       <type>int</type>
diff --git a/Shaders/terrain-haze-ultra.frag b/Shaders/terrain-haze-ultra.frag
index cf36b863a..e640a481e 100644
--- a/Shaders/terrain-haze-ultra.frag
+++ b/Shaders/terrain-haze-ultra.frag
@@ -625,6 +625,22 @@ if (delta_z > 0.0) // we're inside the layer
 		} 
 	}
 	
+// blur of the haze layer edge
+
+float blur_thickness = 50.0;
+float cphi = dot(vec3(0.0, 1.0, 0.0), relPos)/dist;
+float ctlayer = delta_z/dist-0.01 + 0.02 * Noise2D(vec2(cphi,1.0),0.1) -0.01;
+float ctblur = 	0.035 ;
+
+float blur_dist;
+
+if (abs(delta_z) < 400.0)
+	{
+	blur_dist = dist * (1.0-smoothstep(0.0,300.0,-delta_z)) * smoothstep(-400.0,-200.0, -delta_z);
+	blur_dist = blur_dist * smoothstep(ctlayer-4.0*ctblur, ctlayer-ctblur, ct) * (1.0-smoothstep(ctlayer+0.5*ctblur, ctlayer+ctblur, ct));
+	distance_in_layer = max(distance_in_layer, blur_dist);
+	}
+
 
 // ground haze cannot be thinner than aloft visibility in the model,
 // so we need to use aloft visibility otherwise
diff --git a/Shaders/tree-haze.frag b/Shaders/tree-haze.frag
index 5dbfd4306..443e752c7 100644
--- a/Shaders/tree-haze.frag
+++ b/Shaders/tree-haze.frag
@@ -11,8 +11,6 @@ uniform sampler2D texture;
 
 
 varying float yprime_alt;
-//varying float mie_angle;
-
 
 uniform float visibility;
 uniform float avisibility;
@@ -27,6 +25,7 @@ uniform float dust_cover_factor;
 
 
 uniform int quality_level;
+uniform int tquality_level;
 
 const float EarthRadius = 5800000.0;
 const float terminator_width = 200000.0;
@@ -81,6 +80,43 @@ else
 
 }
 
+float rand2D(in vec2 co){
+    return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453);
+}
+
+
+float simple_interpolate(in float a, in float b, in float x)
+{
+return a + smoothstep(0.0,1.0,x) * (b-a);
+}
+
+float interpolatedNoise2D(in float x, in float y)
+{
+      float integer_x    = x - fract(x);
+      float fractional_x = x - integer_x;
+
+      float integer_y    = y - fract(y);
+      float fractional_y = y - integer_y;
+
+      float v1 = rand2D(vec2(integer_x, integer_y));
+      float v2 = rand2D(vec2(integer_x+1.0, integer_y));
+      float v3 = rand2D(vec2(integer_x, integer_y+1.0));
+      float v4 = rand2D(vec2(integer_x+1.0, integer_y +1.0));
+
+      float i1 = simple_interpolate(v1 , v2 , fractional_x);
+      float i2 = simple_interpolate(v3 , v4 , fractional_x);
+
+      return simple_interpolate(i1 , i2 , fractional_y);
+}
+
+
+
+float Noise2D(in vec2 coord, in float wavelength)
+{
+return interpolatedNoise2D(coord.x/wavelength, coord.y/wavelength);
+
+}
+
 void main()
 {
 
@@ -170,6 +206,23 @@ if (delta_z > 0.0) // we're inside the layer
 	}
 	
 
+// blur of the haze layer edge
+
+float blur_thickness = 50.0;
+float cphi = dot(vec3(0.0, 1.0, 0.0), relPos)/dist;
+float ctlayer; 
+float ctblur = 	0.035 ;
+
+float blur_dist;
+
+if ((abs(delta_z) < 400.0)&&(quality_level>5)&&(tquality_level>5))
+	{
+	ctlayer = delta_z/dist-0.01 + 0.02 * Noise2D(vec2(cphi,1.0),0.1) -0.01;
+	blur_dist = dist * (1.0-smoothstep(0.0,300.0,-delta_z)) * smoothstep(-400.0,-200.0, -delta_z);
+	blur_dist = blur_dist * smoothstep(ctlayer-4.0*ctblur, ctlayer-ctblur, ct) * (1.0-smoothstep(ctlayer+0.5*ctblur, ctlayer+ctblur, ct));
+	distance_in_layer = max(distance_in_layer, blur_dist);
+	}
+
 // ground haze cannot be thinner than aloft visibility in the model,
 // so we need to use aloft visibility otherwise