Autumn colors by pixel postprocessing with color rotation encoded in the terrain texture alpha channel, used for Atmospheric Light Scattering

Effects/terrain-default.eff

@@ -636,6 +636,11 @@
         <type>float</type>
         <value><use>moonlight</use></value>
       </uniform>
+      <uniform>
+        <name>season</name>
+        <type>float</type>
+        <value><use>season</use></value>
+      </uniform>
       <uniform>
         <name>quality_level</name>
         <type>int</type>

Materials/regions/materials.xml

@@ -1483,7 +1483,7 @@
   <name>CropGrassCover</name>
   <name>CropGrass</name>
   <name>Grassland</name>
-  <texture>Terrain/cropgrass-hires.png</texture>
+  <texture>Terrain/cropgrass-hires-autumn.png</texture>
   <object-mask>Terrain/cropgrass-hires.mask.png</object-mask>
   <xsize>2000</xsize>
   <ysize>2000</ysize>
@@ -1549,7 +1549,7 @@
 <material include="Materials/regions/european.xml">
   <name>Town</name>
   <name>SubUrban</name>
-  <texture>Terrain/town-europe.png</texture>
+  <texture>Terrain/town-europe-autumn.png</texture>
   <object-mask>Terrain/town-europe.mask.png</object-mask>
   <xsize>1024</xsize>
   <ysize>1024</ysize>
@@ -1611,7 +1611,7 @@
   <name>MixedCropPastureCover</name>
   <name>MixedCrop</name>
   <name>ComplexCrop</name>
-  <texture>Terrain/irrcrop-europe.png</texture>
+  <texture>Terrain/irrcrop-europe-autumn.png</texture>
   <object-mask>Terrain/irrcrop-europe.mask.png</object-mask>
   <xsize>2000</xsize>
   <ysize>2000</ysize>
@@ -1929,7 +1929,7 @@
   <name>Scrub</name>
   <name>Sclerophyllous</name>
   <texture-set>
-   <texture>Terrain/shrub1.png</texture>
+   <texture>Terrain/shrub1-autumn.png</texture>
    <texture n="11">Terrain/grass_green_hires.png</texture>
    <texture n="12">Terrain/herbtundra_iceland.png</texture>
   </texture-set>
@@ -2072,7 +2072,7 @@
   <name>DeciduousForest</name>
   <name>Bog</name>
   <name>Heath</name>
-  <texture>Terrain/deciduous-hires.png</texture>
+  <texture>Terrain/deciduous-hires-autumn.png</texture>
   <xsize>2000</xsize>
   <ysize>2000</ysize>
   <light-coverage>10000000.0</light-coverage>
@@ -2099,7 +2099,7 @@
   <name>MixedForestCover</name>
   <name>MixedForest</name>
   <name>RainForest</name>
-  <texture>Terrain/mixedforest-hires.png</texture>
+  <texture>Terrain/mixedforest-hires-autumn.png</texture>
   <xsize>2000</xsize>
   <ysize>2000</ysize>
   <light-coverage>5000000.0</light-coverage>
@@ -2235,7 +2235,7 @@
   <name>Scrub</name>
   <name>Sclerophyllous</name>
   <texture-set>
-   <texture>Terrain/shrub1.png</texture>
+   <texture>Terrain/shrub1-autumn.png</texture>
    <texture n="11">Terrain/grass_hires.png</texture>
    <texture n="12">Terrain/dirtrock.png</texture>
    <texture n="12">Terrain/dirtrock.png</texture>
@@ -2534,7 +2534,7 @@
   <name>Cemetery</name>
   <effect>Effects/landmass-nowood</effect>
   <texture-set>
-   <texture>Terrain/tundra2.png</texture>
+   <texture>Terrain/tundra2-autumn.png</texture>
    <texture n="11">Terrain/grass_hires.png</texture>
    <texture n="12">Terrain/rock.png</texture>
   </texture-set>
@@ -2755,14 +2755,14 @@
   <effect>Effects/crop</effect>
   <name>DryCropPastureCover</name>
   <name>DryCrop</name>
-  <texture>Terrain/drycrop1.png</texture>
+  <texture>Terrain/drycrop1-autumn.png</texture>
-  <texture>Terrain/drycrop2.png</texture>
+  <!--<texture>Terrain/drycrop2.png</texture>
   <texture>Terrain/drycrop3.png</texture>
-  <texture>Terrain/drycrop4.png</texture>
+  <texture>Terrain/drycrop4.png</texture>-->
   <object-mask>Terrain/drycrop1.mask.png</object-mask>
   <object-mask>Terrain/drycrop2.mask.png</object-mask>
   <object-mask>Terrain/drycrop3.mask.png</object-mask>
-  <object-mask>Terrain/drycrop4.mask.png</object-mask>
+  <!--<object-mask>Terrain/drycrop4.mask.png</object-mask>-->
   <xsize>2000</xsize>
   <ysize>2000</ysize>
   <solid>1</solid>
@@ -2902,7 +2902,7 @@
   <name>CropWood</name>
   <name>AgroForest</name>
   <effect>Effects/landmass-nowood</effect>
-  <texture>Terrain/cropwood.png</texture>
+  <texture>Terrain/cropwood-autumn.png</texture>
 	<object-mask>Terrain/cropwood.mask.png</object-mask>
   <xsize>2000</xsize>
   <ysize>2000</ysize>

Shaders/terrain-haze-detailed.frag

@@ -36,6 +36,7 @@ uniform float wetness;
 uniform float fogstructure;
 uniform float snow_thickness_factor;
 uniform float cloud_self_shading;
+uniform float season;
 uniform float transition_model;
 uniform float hires_overlay_bias;
 uniform int quality_level;
@@ -204,6 +205,7 @@ float noise_2000m = Noise2D(rawPos.xy, 2000.0);
 // get the texels
 
     texel = texture2D(texture, gl_TexCoord[0].st);
+    float local_autumn_factor = texel.a;
 
     float distortion_factor = 1.0;
     vec2 stprime;
@@ -278,6 +280,7 @@ if (tquality_level > 2)
 	nSum = nSum + 0.4 * (1.0 -smoothstep(0.9,0.95, abs(steepness)+ 0.05 * (noise_50m - 0.5))) * min(1.0, 2.0 * transition_model);
 	mix_factor = smoothstep(0.5, 0.54, nSum);
         texel = mix(texel, mix_texel, mix_factor);
+        local_autumn_factor = texel.a;
 	}
    
    // then the detail texture overlay	
@@ -297,11 +300,31 @@ if (tquality_level > 3)
 		mix_factor = smoothstep(0.47, 0.54, nSum +hires_overlay_bias - dist_fact);
 		if (mix_factor > 0.8) {mix_factor = 0.8;}
 		texel =  mix(texel, detail_texel,mix_factor);
+		local_autumn_factor = texel.a;				
 		}
 	}
    }
 
 
+
+// autumn colors
+
+float autumn_factor = season * 2.0 * (1.0 - local_autumn_factor) ;
+
+
+texel.r = min(1.0, (1.0 + 2.5 * autumn_factor) * texel.r);
+texel.g = texel.g;
+texel.b = max(0.0, (1.0 - 4.0 * autumn_factor) *  texel.b);
+
+
+if (local_autumn_factor < 1.0)
+	{
+	intensity = length(texel.rgb) * (1.0 - 0.5 * smoothstep(1.1,2.0,season));
+	texel.rgb = intensity * normalize(mix(texel.rgb, vec3(0.23,0.17,0.08), smoothstep(1.1,2.0, season)));
+	}
+
+
+
 const vec4 dust_color  = vec4 (0.76, 0.71, 0.56, 1.0);
 const vec4 lichen_color = vec4 (0.17, 0.20, 0.06, 1.0);;
 //float snow_alpha;

Shaders/terrain-haze-ultra.frag

@@ -44,7 +44,6 @@ uniform float wetness;
 uniform float fogstructure;
 uniform float snow_thickness_factor;
 uniform float cloud_self_shading;
-uniform float moonlight;
 uniform float season;
 uniform float windspeed;
 uniform float grain_strength;
@@ -276,7 +275,7 @@ float dotnoisegrad_10m;
 // get the texels
 
 
-    float local_autumn_factor = texel.a;
+
     float distortion_factor = 1.0;
     vec2 stprime;
     int flag = 1;
@@ -285,6 +284,7 @@ float dotnoisegrad_10m;
     float snow_alpha;
 
     texel = texture2D(texture, gl_TexCoord[0].st);
+    float local_autumn_factor = texel.a;
 	grain_texel = texture2D(grain_texture, gl_TexCoord[0].st * 25.0);
 	gradient_texel = texture2D(gradient_texture, gl_TexCoord[0].st * 4.0);
 

gui/dialogs/environment-settings.xml

@@ -288,6 +288,42 @@
       <col>3</col>
     </text>
 
+
+    <text>
+      <label>Season</label>
+      <halign>left</halign>
+      <row>7</row>
+      <col>0</col>
+    </text>
+    
+    <text>
+      <label>summer</label>
+      <halign>right</halign>
+      <row>7</row>
+      <col>1</col>
+    </text>
+        
+    <slider>
+      <name>season</name>
+      <row>7</row>
+      <col>2</col>
+      <min>0.0</min>
+      <max>2.0</max>
+      <live>true</live>
+      <property>/environment/season</property>
+      <binding>
+        <command>dialog-apply</command>
+        <object-name>season</object-name>
+      </binding>
+    </slider>
+
+    <text>
+      <label>late autumn</label>
+      <halign>left</halign>
+      <row>7</row>
+      <col>3</col>
+    </text>
+
   </group>
   
   <hrule/>