Compositor: Use a logarithmic depth buffer in the ALS pipeline.

This might not be a definitive solution to fix z-fighting issues, but it's a
good solution meanwhile and can be implemented easily on any shader just by
adding a few lines.

Compositor/Effects/model-default.eff

@@ -473,7 +473,7 @@
         <use>vertex-program-two-side</use>
       </vertex-program-two-side>
       <program>
-        <vertex-shader>Shaders/ALS/generic-base.vert</vertex-shader>
+        <vertex-shader>Shaders/ALS/model-base.vert</vertex-shader>
         <vertex-shader>Shaders/ALS/shadows-include.vert</vertex-shader>
         <fragment-shader>Shaders/ALS/model-base.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/hazes.frag</fragment-shader>

Compositor/Effects/model-interior-display.eff

@@ -69,7 +69,7 @@
         <use>vertex-program-two-side</use>
       </vertex-program-two-side>
       <program>
-        <vertex-shader>Shaders/ALS/generic-base.vert</vertex-shader>
+        <vertex-shader>Shaders/ALS/model-base.vert</vertex-shader>
         <fragment-shader>Shaders/ALS/model-interior-base.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/hazes.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/secondary_lights.frag</fragment-shader>

Compositor/Effects/model-interior.eff

@@ -742,7 +742,7 @@
         <use>vertex-program-two-side</use>
       </vertex-program-two-side>
       <program>
-        <vertex-shader>Shaders/ALS/generic-base.vert</vertex-shader>
+        <vertex-shader>Shaders/ALS/model-base.vert</vertex-shader>
         <fragment-shader>Shaders/ALS/model-interior-base.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/hazes.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/secondary_lights.frag</fragment-shader>

Compositor/Effects/terrain-default.eff

@@ -2108,7 +2108,7 @@
         </internal-format>
       </texture-unit>
       <program>
-        <vertex-shader>Shaders/ALS/generic-base.vert</vertex-shader>
+        <vertex-shader>Shaders/ALS/terrain-base.vert</vertex-shader>
         <vertex-shader>Shaders/ALS/shadows-include.vert</vertex-shader>
         <fragment-shader>Shaders/ALS/terrain-base.frag</fragment-shader>
         <fragment-shader>Shaders/ALS/hazes.frag</fragment-shader>

Compositor/Shaders/ALS/3dcloud-detailed.vert

@@ -1,6 +1,8 @@
 // -*-C++-*-
 #version 120
 
+uniform float fg_Fcoef;
+
 varying float fogFactor;
 varying vec3 hazeColor;
 varying float mie_frag;
@@ -151,7 +153,8 @@ void main(void)
     // Final position of the sprite
     vec3 relVector = gl_Position.xyz - ep.xyz;
     gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
-
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 
    // Light at the final position
 

Compositor/Shaders/ALS/3dcloud.vert

@@ -1,6 +1,8 @@
 // -*-C++-*-
 #version 120
 
+uniform float fg_Fcoef;
+
 varying float fogFactor;
 varying vec3 hazeColor;
 
@@ -134,7 +136,8 @@ void main(void)
     // Final position of the sprite
     vec3 relVector = gl_Position.xyz - ep.xyz;
     gl_Position = gl_ModelViewProjectionMatrix * gl_Position;
-
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 
    // Light at the final position
 

Compositor/Shaders/ALS/agriculture.frag

@@ -12,6 +12,7 @@ varying vec3 worldPos;
 varying vec3 ecViewdir;
 
 
+uniform float fg_Fcoef;
 
 uniform sampler2D texture;
 uniform sampler2D mix_texture;
@@ -22,6 +23,8 @@ uniform sampler2D gradient_texture;
 varying float steepness;
 varying vec2 grad_dir;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -658,6 +661,6 @@ fragColor.rgb = mix(hazeColor  + secondary_light * fog_backscatter(mvisibility),
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor =  fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 }
 

Compositor/Shaders/ALS/airfield.frag

@@ -11,12 +11,16 @@ varying vec2 rawPos;
 varying vec3 ecViewdir;
 
 
+uniform float fg_Fcoef;
+
 uniform sampler2D texture;
 uniform sampler2D overlay_texture;
 uniform sampler2D grain_texture;
 
 varying float steepness;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -520,6 +524,6 @@ fragColor.rgb = mix(hazeColor+secondary_light * fog_backscatter(mvisibility), fr
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }

Compositor/Shaders/ALS/cliffs.frag

@@ -16,6 +16,10 @@ varying vec3 ecViewdir;
 varying float steepness;
 varying vec2 grad_dir;
 
+varying float flogz;
+
+
+uniform float fg_Fcoef;
 
 uniform float visibility;
 uniform float avisibility;
@@ -614,7 +618,7 @@ fragColor.rgb = mix(hazeColor + secondary_light * fog_backscatter(mvisibility),
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }
 

Compositor/Shaders/ALS/drunway.frag

@@ -10,6 +10,8 @@ varying vec2 rawPos;
 varying vec3 ecViewdir;
 
 
+uniform float fg_Fcoef;
+
 uniform sampler2D texture;
 uniform sampler2D NormalTex;
 uniform sampler2D mix_texture;
@@ -17,6 +19,8 @@ uniform sampler2D grain_texture;
 
 varying float steepness;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -499,6 +503,6 @@ fragColor.rgb = mix(hazeColor +secondary_light * fog_backscatter(mvisibility) ,
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 }
 

Compositor/Shaders/ALS/model-base.vert

@@ -0,0 +1,254 @@
+// -*-C++-*-
+#version 120
+
+// Shader that uses OpenGL state values to do per-pixel lighting
+//
+// The only light used is gl_LightSource[0], which is assumed to be
+// directional.
+//
+// Diffuse colors come from the gl_Color, ambient from the material. This is
+// equivalent to osg::Material::DIFFUSE.
+// Haze part added by Thorsten Renk, Oct. 2011
+
+
+#define MODE_OFF 0
+#define MODE_DIFFUSE 1
+#define MODE_AMBIENT_AND_DIFFUSE 2
+
+uniform float fg_Fcoef;
+
+// The constant term of the lighting equation that doesn't depend on
+// the surface normal is passed in gl_{Front,Back}Color. The alpha
+// component is set to 1 for front, 0 for back in order to work around
+// bugs with gl_FrontFacing in the fragment shader.
+varying vec4 diffuse_term;
+varying vec3 normal;
+varying vec3 relPos;
+varying vec4 ecPosition;
+
+varying float yprime_alt;
+varying float mie_angle;
+
+uniform int colorMode;
+uniform float hazeLayerAltitude;
+uniform float terminator;
+uniform float terrain_alt; 
+uniform float avisibility;
+uniform float visibility;
+uniform float overcast;
+uniform float ground_scattering;
+uniform float moonlight;
+
+
+void setupShadows(vec4 eyeSpacePos);
+
+// This is the value used in the skydome scattering shader - use the same here for consistency?
+const float EarthRadius = 5800000.0;
+const float terminator_width = 200000.0;
+
+
+float earthShade;
+
+float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
+{
+//x = x - 0.5;
+
+// use the asymptotics to shorten computations
+if (x < -15.0) {return 0.0;}
+
+return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
+}
+
+
+void main()
+{
+
+  vec4 light_diffuse;
+  vec4 light_ambient;
+  vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
+  vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight;
+
+
+  //float yprime_alt;
+  float yprime;
+  float lightArg;
+  float intensity;
+  float vertex_alt;
+  float scattering;
+
+// this code is copied from default.vert
+
+    ecPosition = gl_ModelViewMatrix * gl_Vertex;
+    gl_Position = ftransform();
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
+    gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
+    normal = gl_NormalMatrix * gl_Normal;
+    vec4 ambient_color, diffuse_color;
+    if (colorMode == MODE_DIFFUSE) {
+        diffuse_color = gl_Color;
+        ambient_color = gl_FrontMaterial.ambient;
+    } else if (colorMode == MODE_AMBIENT_AND_DIFFUSE) {
+        diffuse_color = gl_Color;
+        ambient_color = gl_Color;
+    } else {
+        diffuse_color = gl_FrontMaterial.diffuse;
+        ambient_color = gl_FrontMaterial.ambient;
+    }
+   
+    
+
+    // here start computations for the haze layer
+    // we need several geometrical quantities
+
+    // first current altitude of eye position in model space
+    vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
+    
+    // and relative position to vector
+    relPos = gl_Vertex.xyz - ep.xyz;
+
+    // unfortunately, we need the distance in the vertex shader, although the more accurate version
+    // is later computed in the fragment shader again
+    float dist = length(relPos);
+
+    // altitude of the vertex in question, somehow zero leads to artefacts, so ensure it is at least 100m
+    vertex_alt = max(gl_Vertex.z,100.0);
+    scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, vertex_alt); 
+
+
+    // branch dependent on daytime
+
+if (terminator < 1000000.0) // the full, sunrise and sunset computation
+{
+    
+
+    // establish coordinates relative to sun position
+
+    vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
+    vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
+  
+
+    
+    // yprime is the distance of the vertex into sun direction
+    yprime = -dot(relPos, lightHorizon);
+
+    // this gets an altitude correction, higher terrain gets to see the sun earlier
+    yprime_alt = yprime - sqrt(2.0 * EarthRadius * vertex_alt);
+
+    // two times terminator width governs how quickly light fades into shadow
+    // now the light-dimming factor
+    earthShade = 0.6 * (1.0 - smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt)) + 0.4;
+  
+   // parametrized version of the Flightgear ground lighting function
+    lightArg = (terminator-yprime_alt)/100000.0;
+
+    // directional scattering for low sun
+    if (lightArg < 10.0)
+    	{mie_angle = (0.5 *  dot(normalize(relPos), normalize(lightFull)) ) + 0.5;}
+    else 
+	{mie_angle = 1.0;}
+
+
+
+
+   light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0);
+   light_diffuse.g = light_func(lightArg, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
+   light_diffuse.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
+   light_diffuse.a = 1.0;
+   light_diffuse = light_diffuse * scattering;
+
+
+   light_ambient.r = light_func(lightArg, 0.236, 0.253, 1.073, 0.572, 0.33);
+   light_ambient.g = light_ambient.r * 0.4/0.33; 
+   light_ambient.b = light_ambient.r * 0.5/0.33; 
+   light_ambient.a = 1.0;
+
+
+
+
+// correct ambient light intensity and hue before sunrise
+if (earthShade < 0.5)
+	{
+	//light_ambient = light_ambient * (0.7 + 0.3 * smoothstep(0.2, 0.5, earthShade));
+	intensity = length(light_ambient.xyz); 
+
+	light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb,  shadedFogColor, 1.0 -smoothstep(0.4, 0.8,earthShade) ));
+	light_ambient.rgb = light_ambient.rgb +   moonLightColor *  (1.0 - smoothstep(0.4, 0.5, earthShade));
+
+	intensity = length(light_diffuse.xyz); 
+	light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb,  shadedFogColor, 1.0 -smoothstep(0.4, 0.7,earthShade) ));
+	}
+
+
+// the haze gets the light at the altitude of the haze top if the vertex in view is below
+// but the light at the vertex if the vertex is above
+
+vertex_alt = max(vertex_alt,hazeLayerAltitude);
+
+if (vertex_alt > hazeLayerAltitude)
+	{
+	if (dist > 0.8 * avisibility)
+		{
+		vertex_alt = mix(vertex_alt, hazeLayerAltitude, smoothstep(0.8*avisibility, avisibility, dist));
+		yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
+		}
+	}
+else
+	{
+	vertex_alt = hazeLayerAltitude;
+	yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
+	}
+
+}
+else // the faster, full-day version without lightfields
+{
+    //vertex_alt = max(gl_Vertex.z,100.0);
+ 
+    earthShade = 1.0;
+    mie_angle = 1.0;
+    
+    if (terminator > 3000000.0)
+    	{light_diffuse = vec4 (1.0, 1.0, 1.0, 0.0);
+	light_ambient = vec4 (0.33, 0.4, 0.5, 0.0); }
+    else
+	{
+
+	lightArg = (terminator/100000.0 - 10.0)/20.0;
+	light_diffuse.b = 0.78  + lightArg * 0.21;
+	light_diffuse.g = 0.907 + lightArg * 0.091;
+	light_diffuse.r = 0.904 + lightArg * 0.092;
+	light_diffuse.a = 1.0;
+
+	light_ambient.r = 0.316 + lightArg * 0.016;
+	light_ambient.g = light_ambient.r * 0.4/0.33; 
+   	light_ambient.b = light_ambient.r * 0.5/0.33;
+	light_ambient.a = 1.0;
+	}  
+    
+    light_diffuse = light_diffuse * scattering;
+    yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
+}
+ 
+
+// default lighting based on texture and material using the light we have just computed
+
+ diffuse_term = diffuse_color* light_diffuse;
+    vec4 constant_term = gl_FrontMaterial.emission + ambient_color *
+        (gl_LightModel.ambient +  light_ambient);
+    // Super hack: if diffuse material alpha is less than 1, assume a
+    // transparency animation is at work
+    if (gl_FrontMaterial.diffuse.a < 1.0)
+        diffuse_term.a = gl_FrontMaterial.diffuse.a;
+    else
+        diffuse_term.a = gl_Color.a;
+    // Another hack for supporting two-sided lighting without using
+    // gl_FrontFacing in the fragment shader.
+    gl_FrontColor.rgb = constant_term.rgb;  gl_FrontColor.a = 1.0;
+    gl_BackColor.rgb = constant_term.rgb; gl_BackColor.a = 0.0;
+
+    setupShadows(gl_ModelViewMatrix * gl_Vertex);
+}
+
+
+
+

Compositor/Shaders/ALS/model-interior-detailed.vert

@@ -15,6 +15,8 @@
 #define MODE_DIFFUSE 1
 #define MODE_AMBIENT_AND_DIFFUSE 2
 
+uniform float fg_Fcoef;
+
 // The constant term of the lighting equation that doesn't depend on
 // the surface normal is passed in gl_{Front,Back}Color. The alpha
 // component is set to 1 for front, 0 for back in order to work around
@@ -85,6 +87,8 @@ void main()
 
     //vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
     gl_Position = ftransform();
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
     gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
     normal = gl_NormalMatrix * gl_Normal;
     vec4 ambient_color, diffuse_color;

Compositor/Shaders/ALS/model-ultra.vert

@@ -16,6 +16,8 @@ varying	float	alpha;
 attribute	vec3	tangent;
 attribute	vec3	binormal;
 
+uniform float fg_Fcoef;
+
 uniform	float		pitch;
 uniform	float		roll;
 uniform	float		hdg;
@@ -113,6 +115,8 @@ void	main(void)
 					  * (gl_LightModel.ambient + gl_LightSource[0].ambient);
 		
 		gl_Position = ftransform();
+        // logarithmic depth
+        gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 		gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
 
         setupShadows(ecPosition);

Compositor/Shaders/ALS/rock.frag

@@ -15,6 +15,10 @@ varying vec3 ecViewdir;
 varying float steepness;
 varying vec2 grad_dir;
 
+varying float flogz;
+
+
+uniform float fg_Fcoef;
 
 uniform float visibility;
 uniform float avisibility;
@@ -673,7 +677,7 @@ fragColor.rgb = mix(hazeColor + secondary_light * fog_backscatter(mvisibility),
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }
 

Compositor/Shaders/ALS/runway.frag

@@ -11,11 +11,15 @@ varying vec3 worldPos;
 varying vec3 ecViewdir;
 
 
+uniform float fg_Fcoef;
+
 uniform sampler2D texture;
 uniform sampler2D NormalTex;
 
 varying float steepness;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -526,7 +530,7 @@ fragColor.rgb = mix(hazeColor +secondary_light * fog_backscatter(mvisibility), f
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }
 

Compositor/Shaders/ALS/skydome.vert

@@ -5,7 +5,8 @@
 // Atmospheric scattering shader for flightgear
 // Written by Lauri Peltonen (Zan)
 // Implementation of O'Neil's algorithm
- 
+
+uniform float fg_Fcoef;
  
 uniform mat4 osg_ViewMatrix;
 uniform mat4 osg_ViewMatrixInverse;
@@ -295,4 +296,6 @@ void main()
 
     // Transform
     gl_Position = gl_ModelViewProjectionMatrix * finalVertex;
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 }

Compositor/Shaders/ALS/terrain-base.frag

@@ -8,12 +8,16 @@ varying vec3 normal;
 varying vec3 relPos;
 
 
+uniform float fg_Fcoef;
+
 uniform sampler2D texture;
 
 
 varying float yprime_alt;
 varying float mie_angle;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -245,6 +249,6 @@ fragColor.rgb = mix(hazeColor, fragColor.rgb,transmission);
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 }
 

Compositor/Shaders/ALS/terrain-base.vert

@@ -27,6 +27,8 @@ varying vec4 ecPosition;
 varying float yprime_alt;
 varying float mie_angle;
 
+varying float flogz;
+
 uniform int colorMode;
 uniform float hazeLayerAltitude;
 uniform float terminator;
@@ -78,6 +80,8 @@ void main()
 
     ecPosition = gl_ModelViewMatrix * gl_Vertex;
     gl_Position = ftransform();
+    // logarithmic depth
+    flogz = 1.0 + gl_Position.w;
     gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
     normal = gl_NormalMatrix * gl_Normal;
     vec4 ambient_color, diffuse_color;

Compositor/Shaders/ALS/terrain-detailed.frag

@@ -10,6 +10,7 @@ varying vec2 rawPos;
 varying vec3 worldPos;
 
 
+uniform float fg_Fcoef;
 
 uniform sampler2D texture;
 uniform sampler2D detail_texture;
@@ -19,6 +20,8 @@ uniform sampler2D mix_texture;
 //varying float mie_angle;
 varying float steepness;
 
+varying float flogz;
+
 
 uniform float visibility;
 uniform float avisibility;
@@ -501,7 +504,7 @@ fragColor.rgb = mix(clamp(hazeColor,0.0,1.0) , clamp(fragColor.rgb,0.0,1.0),tran
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }
 

Compositor/Shaders/ALS/terrain-detailed.vert

@@ -29,6 +29,8 @@ varying vec3 worldPos;
 varying float mie_angle;
 varying float steepness;
 
+varying float flogz;
+
 
 uniform int colorMode;
 uniform float hazeLayerAltitude;
@@ -94,6 +96,8 @@ void main()
 
     //vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
     gl_Position = ftransform();
+    // logarithmic depth
+    flogz = 1.0 + gl_Position.w;
     gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
     normal = gl_NormalMatrix * gl_Normal;
     //nvec = (gl_NormalMatrix * gl_Normal).xy;

Compositor/Shaders/ALS/terrain-ultra.frag

@@ -12,6 +12,8 @@ varying vec3 ecViewdir;
 varying vec2 grad_dir;
 
 
+uniform float fg_Fcoef;
+
 uniform sampler2D texture;
 uniform sampler2D detail_texture;
 uniform sampler2D mix_texture;
@@ -22,7 +24,7 @@ uniform sampler2D gradient_texture;
 
 varying float steepness;
 
-
+varying float flogz;
 
 uniform float visibility;
 uniform float avisibility;
@@ -664,6 +666,6 @@ fragColor.rgb = mix(hazeColor+secondary_light * fog_backscatter(mvisibility) , f
 fragColor.rgb = filter_combined(fragColor.rgb);
 
 gl_FragColor = fragColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 }
 

Compositor/Shaders/ALS/terrain-ultra.vert

@@ -30,6 +30,8 @@ varying vec2 grad_dir;
 varying float mie_angle;
 varying float steepness;
 
+varying float flogz;
+
 uniform int colorMode;
 
 uniform bool raise_vertex;
@@ -104,6 +106,8 @@ void main()
    	gl_Position =  gl_ModelViewProjectionMatrix * pos;
 	}
    else gl_Position = ftransform();
+   // logarithmic depth
+   flogz = 1.0 + gl_Position.w;
 
 
 // this code is copied from default.vert

Compositor/Shaders/ALS/tree-shadow.vert

@@ -15,6 +15,8 @@
 #define MODE_DIFFUSE 1
 #define MODE_AMBIENT_AND_DIFFUSE 2
 
+uniform float fg_Fcoef;
+
 // The constant term of the lighting equation that doesn't depend on
 // the surface normal is passed in gl_{Front,Back}Color. The alpha
 // component is set to 1 for front, 0 for back in order to work around
@@ -215,6 +217,8 @@ void main()
   // Move to correct location (stored in gl_Color)
   position = position + gl_Color.xyz;
   gl_Position   = gl_ModelViewProjectionMatrix * vec4(position,1.0);
+  // logarithmic depth
+  gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 
   vec3 ecPosition = vec3(gl_ModelViewMatrix * vec4(position, 1.0));
   //normal = normalize(-ecPosition);

Compositor/Shaders/ALS/tree.vert

@@ -15,6 +15,8 @@
 #define MODE_DIFFUSE 1
 #define MODE_AMBIENT_AND_DIFFUSE 2
 
+uniform float fg_Fcoef;
+
 // The constant term of the lighting equation that doesn't depend on
 // the surface normal is passed in gl_{Front,Back}Color. The alpha
 // component is set to 1 for front, 0 for back in order to work around
@@ -130,6 +132,8 @@ void main()
   // Move to correct location (stored in gl_Color)
   position = position + gl_Color.xyz;
   gl_Position   = gl_ModelViewProjectionMatrix * vec4(position,1.0);
+  // logarithmic depth
+  gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
 
   vec3 ecPosition = vec3(gl_ModelViewMatrix * vec4(position, 1.0));
   //normal = normalize(-ecPosition);

Compositor/Shaders/ALS/urban.vert

@@ -15,6 +15,8 @@
 #define MODE_DIFFUSE 1
 #define MODE_AMBIENT_AND_DIFFUSE 2
 
+uniform float fg_Fcoef;
+
 // The constant term of the lighting equation that doesn't depend on
 // the surface normal is passed in gl_{Front,Back}Color. The alpha
 // component is set to 1 for front, 0 for back in order to work around
@@ -105,6 +107,8 @@ void main()
 // this code is copied from default.vert
 
     gl_Position = ftransform();
+    // logarithmic depth
+    gl_Position.z = (log2(max(1e-6, 1.0 + gl_Position.w)) * fg_Fcoef - 1.0) * gl_Position.w;
     gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
     //normal = gl_NormalMatrix * gl_Normal;
     vec4 ambient_color, diffuse_color;

Compositor/Shaders/ALS/water-base.frag

@@ -8,6 +8,8 @@
 
 #version 120
 
+uniform float fg_Fcoef;
+
 uniform sampler2D water_normalmap;
 uniform sampler2D water_dudvmap;
 uniform sampler2D sea_foam;
@@ -29,6 +31,8 @@ varying float earthShade;
 varying float yprime_alt;
 varying float mie_angle;
 
+varying float flogz;
+
 uniform    float WaveFreq ;
 uniform    float WaveAmp ;
 uniform    float WaveSharp ;
@@ -556,5 +560,5 @@ if (intensity > 0.0) // this needs to be a condition, because otherwise hazeColo
 	finalColor.rgb = filter_combined(finalColor.rgb);
 
 	gl_FragColor = finalColor;
-
+    gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 }

Compositor/Shaders/ALS/water-high.frag

@@ -8,6 +8,8 @@
 
 #version 120
 
+uniform float fg_Fcoef;
+
 uniform sampler2D water_normalmap;
 uniform sampler2D water_dudvmap;
 uniform sampler2D sea_foam;
@@ -34,6 +36,8 @@ varying float yprime_alt;
 varying float mie_angle;
 varying float steepness;
 
+varying float flogz;
+
 uniform    float WaveFreq ;
 uniform    float WaveAmp ;
 uniform    float WaveSharp ;
@@ -738,6 +742,6 @@ finalColor.rgb = filter_combined(finalColor.rgb);
 
 
 gl_FragColor = finalColor;
-
+gl_FragDepth = log2(flogz) * fg_Fcoef * 0.5;
 
 }

Compositor/Shaders/ALS/water.vert

@@ -7,6 +7,8 @@
 
 #version 120
 
+varying float flogz;
+
 varying vec4 waterTex1;
 varying vec4 waterTex2;
 varying vec4 waterTex4;
@@ -119,7 +121,8 @@ void main(void)
 
 //     fog_Func(fogType);
     gl_Position = ftransform();
-
+    // logarithmic depth
+    flogz = 1.0 + gl_Position.w;
 
 
 // here start computations for the haze layer