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Rayleigh scattering for light reflected from the terrain, leading to blue hazy distance effects and redshift of reflected sunlight, work in progress, only terrain and water done

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Thorsten Renk 2014-10-03 13:49:38 +03:00
parent bd5b09b0ac
commit 4ac3620f5b
7 changed files with 151 additions and 64 deletions
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7
Effects/terrain-default.eff
View file

@ -112,6 +112,7 @@
<cloud_self_shading><use>/environment/cloud-self-shading</use></cloud_self_shading>
<moonlight><use>/environment/moonlight</use></moonlight>
<season><use>/environment/season</use></season>
<air_pollution><use>/environment/air-pollution-norm</use></air_pollution>
<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>
@ -293,6 +294,7 @@
<fragment-shader>Shaders/terrain-haze-ultra.frag</fragment-shader>
<fragment-shader>Shaders/noise.frag</fragment-shader>
<fragment-shader>Shaders/cloud-shadowfunc.frag</fragment-shader>
<fragment-shader>Shaders/hazes.frag</fragment-shader>
</program>
<uniform>
<name>grain_strength</name>
@ -429,6 +431,11 @@
<type>float</type>
<value><use>season</use></value>
</uniform>
<uniform>
<name>air_pollution</name>
<type>float</type>
<value><use>air_pollution</use></value>
</uniform>
<uniform>
<name>cloudpos1_x</name>
<type>float</type>

13
Effects/water-inland.eff
View file

@ -362,6 +362,7 @@
<vertex-shader>Shaders/water_lightfield.vert</vertex-shader>
<fragment-shader>Shaders/water_lightfield.frag</fragment-shader>
<fragment-shader>Shaders/cloud-shadowfunc.frag</fragment-shader>
<fragment-shader>Shaders/hazes.frag</fragment-shader>
</program>
<!--<uniform>
<name>water_reflection</name>
@ -532,7 +533,17 @@
<type>float</type>
<value><use>cloud_self_shading</use></value>
</uniform>
<uniform>
<uniform>
<name>fogstructure</name>
<type>float</type>
<value><use>fogstructure</use></value>
</uniform>
<uniform>
<name>air_pollution</name>
<type>float</type>
<value><use>air_pollution</use></value>
</uniform>
<uniform>
<name>cloudpos1_x</name>
<type>float</type>
<value><use>cloudpos1_x</use></value>

7
Effects/water.eff
View file

@ -131,6 +131,7 @@
<moonlight><use>/environment/moonlight</use></moonlight>
<fogtype><use>/sim/rendering/shaders/skydome</use></fogtype>
<fogstructure><use>/environment/fog-structure</use></fogstructure>
<air_pollution><use>/environment/air-pollution-norm</use></air_pollution>
<ice_cover><use>/environment/sea/surface/ice-cover</use></ice_cover>
<quality_level><use>/sim/rendering/shaders/landmass</use></quality_level>
<!-- sea colors -->
@ -373,6 +374,7 @@
<vertex-shader>Shaders/water_lightfield.vert</vertex-shader>
<fragment-shader>Shaders/water_lightfield.frag</fragment-shader>
<fragment-shader>Shaders/cloud-shadowfunc.frag</fragment-shader>
<fragment-shader>Shaders/hazes.frag</fragment-shader>
</program>
<!--<uniform>
<name>water_reflection</name>
@ -558,6 +560,11 @@
<type>float</type>
<value><use>fogstructure</use></value>
</uniform>
<uniform>
<name>air_pollution</name>
<type>float</type>
<value><use>air_pollution</use></value>
</uniform>
<uniform>
<name>ice_cover</name>
<type>float</type>

74
Shaders/hazes.frag Normal file
View file

@ -0,0 +1,74 @@
// -*-C++-*-
// standard ALS fog function with exp(-d/D) fading and cutoff at low altitude and exp(-d^2/D^2) at high altitude
const float AtmosphericScaleHeight = 8500.0;
float fog_func (in float targ, in float alt)
{
float fade_mix;
// for large altitude > 30 km, we switch to some component of quadratic distance fading to
// create the illusion of improved visibility range
targ = 1.25 * targ * smoothstep(0.04,0.06,targ); // need to sync with the distance to which terrain is drawn
if (alt < 30000.0)
{return exp(-targ - targ * targ * targ * targ);}
else if (alt < 50000.0)
{
fade_mix = (alt - 30000.0)/20000.0;
return fade_mix * exp(-targ*targ - pow(targ,4.0)) + (1.0 - fade_mix) * exp(-targ - pow(targ,4.0));
}
else
{
return exp(- targ * targ - pow(targ,4.0));
}
}
// altitude correction for exponential drop in atmosphere density
float alt_factor(in float eye_alt, in float vertex_alt)
{
float h0 = AtmosphericScaleHeight;
float h1 = min(eye_alt,vertex_alt);
float h2 = max(eye_alt,vertex_alt);
if ((h2-h1) < 200.0) // use a Taylor-expanded version
{
return 0.5 * (exp(-h2/h0) + exp(-h1/h0));
}
else
{
return h0/(h2-h1) * (exp(-h1/h0) - exp(-h2/h0));
}
}
// Rayleigh in-scatter function
float rayleigh_in_func(in float dist, in float air_pollution, in float avisibility, in float eye_alt, in float vertex_alt)
{
float fade_length = avisibility * (2.5 - 2.0 * air_pollution);
fade_length = fade_length / alt_factor(eye_alt, vertex_alt);
return 1.0-exp(-dist/max(35000.0,fade_length));
}
// Rayleigh out-scattering color shift
vec3 rayleigh_out_shift(in vec3 color, in float outscatter)
{
color.r = color.r * (1.0 - 0.4 * outscatter);
color.g = color.g * (1.0 - 0.8 * outscatter);
color.b = color.b * (1.0 - 1.6 * outscatter);
return color;
}

70
Shaders/terrain-haze-ultra.frag
View file

@ -42,6 +42,7 @@ uniform float fogstructure;
uniform float snow_thickness_factor;
uniform float cloud_self_shading;
uniform float season;
uniform float air_pollution;
uniform float grain_strength;
uniform float intrinsic_wetness;
uniform float transition_model;
@ -62,7 +63,7 @@ uniform int rock_strata;
const float EarthRadius = 5800000.0;
const float terminator_width = 200000.0;
float alt;
//float alt;
float eShade;
float yprime_alt;
float mie_angle;
@ -73,8 +74,10 @@ float Noise2D(in vec2 coord, in float wavelength);
float Noise3D(in vec3 coord, in float wavelength);
float SlopeLines2D(in vec2 coord, in vec2 gradDir, in float wavelength, in float steepness);
float Strata3D(in vec3 coord, in float wavelength, in float variation);
float fog_func (in float targ, in float alt);
float rayleigh_in_func(in float dist, in float air_pollution, in float avisibility, in float eye_alt, in float vertex_alt);
float alt_factor(in float eye_alt, in float vertex_alt);
vec3 rayleigh_out_shift(in vec3 color, in float outscatter);
float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
{
@ -98,39 +101,11 @@ return 1.0 - smoothstep(0.5 * fade_dist, fade_dist, dist);
}
// this determines how light is attenuated in the distance
// physically this should be exp(-arg) but for technical reasons we use a sharper cutoff
// for distance > visibility
float fog_func (in float targ)
{
float fade_mix;
// for large altitude > 30 km, we switch to some component of quadratic distance fading to
// create the illusion of improved visibility range
targ = 1.25 * targ * smoothstep(0.04,0.06,targ); // need to sync with the distance to which terrain is drawn
if (alt < 30000.0)
{return exp(-targ - targ * targ * targ * targ);}
else if (alt < 50000.0)
{
fade_mix = (alt - 30000.0)/20000.0;
return fade_mix * exp(-targ*targ - pow(targ,4.0)) + (1.0 - fade_mix) * exp(-targ - pow(targ,4.0));
}
else
{
return exp(- targ * targ - pow(targ,4.0));
}
}
void main()
{
float alt;
yprime_alt = diffuse_term.a;
//diffuse_term.a = 1.0;
@ -298,7 +273,7 @@ float snownoise_50m = mix(noise_50m, slopenoise_100m, clamp(3.0*(1.0-steepness),
stprime = stprime * distortion_factor * 15.0;
stprime = stprime + normalize(relPos).xy * 0.022 * (noise_10m + 0.5 * noise_5m +0.25 * noise_2m - 0.875 );
detail_texel = texture2D(detail_texture, stprime);
detail_texel = texture2D(detail_texture, stprime);
if (detail_texel.a <0.1) {flag = 0;}
@ -486,14 +461,17 @@ if ((dist < 5000.0)&& (quality_level > 3) && (combined_wetness>0.0))
fragColor = color * texel + specular;
// here comes the terrain haze model
// Rayleigh color shift due to out-scattering
float rayleigh_length = 0.5 * avisibility * (2.5 - 1.9 * air_pollution)/alt_factor(eye_alt, eye_alt+relPos.z);
float outscatter = 1.0-exp(-dist/rayleigh_length);
fragColor.rgb = rayleigh_out_shift(fragColor.rgb,outscatter);
// here comes the terrain haze model
float delta_z = hazeLayerAltitude - eye_alt;
if (dist > 0.04 * min(visibility,avisibility))
//if ((gl_FragCoord.y > ylimit) || (gl_FragCoord.x < zlimit1) || (gl_FragCoord.x > zlimit2))
//if (dist > 40.0)
{
alt = eye_alt;
@ -604,7 +582,7 @@ else
transmission = fog_func(transmission_arg);
transmission = fog_func(transmission_arg, alt);
// there's always residual intensity, we should never be driven to zero
if (eqColorFactor < 0.2) eqColorFactor = 0.2;
@ -661,6 +639,15 @@ if (intensity > 0.0) // this needs to be a condition, because otherwise hazeColo
}
// blue Rayleigh scattering with distance
float rShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt-340000.0) + 0.1;
float lightIntensity = length(diffuse_term.rgb)/1.73 * rShade;
vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
fragColor.rgb = mix(fragColor.rgb, rayleighColor,rayleighStrength);
// finally, mix fog in
fragColor.rgb = mix(eqColorFactor * hazeColor * eShade , fragColor.rgb,transmission);
@ -672,6 +659,15 @@ gl_FragColor = fragColor;
}
else // if dist < threshold no fogging at all
{
// blue Rayleigh scattering with distance
float rShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt-340000.0) + 0.1;
float lightIntensity = length(diffuse_term.rgb)/1.73 * rShade;
vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
fragColor.rgb = mix(fragColor.rgb, rayleighColor,rayleighStrength);
gl_FragColor = fragColor;
}

2
Shaders/terrain-haze-ultra.vert
View file

@ -271,6 +271,8 @@ float shade_depth = 1.0 * smoothstep (0.6,0.95,ground_scattering) * (1.0-smooth
light_ambient.rgb = light_ambient.rgb * (1.0 - shade_depth);
light_diffuse.rgb = light_diffuse.rgb * (1.0 + 1.2 * shade_depth);
// default lighting based on texture and material using the light we have just computed
diffuse_term = diffuse_color* light_diffuse;

42
Shaders/water_lightfield.frag
View file

@ -59,6 +59,7 @@ uniform float ice_cover;
uniform float sea_r;
uniform float sea_g;
uniform float sea_b;
uniform float air_pollution;
uniform int quality_level;
uniform int ocean_flag;
@ -75,6 +76,10 @@ const float EarthRadius = 5800000.0;
//vec3 fog_Func(vec3 color, int type);
float shadow_func (in float x, in float y, in float noise, in float dist);
float fog_func (in float targ, in float alt);
float rayleigh_in_func(in float dist, in float air_pollution, in float avisibility, in float eye_alt, in float vertex_alt);
float alt_factor(in float eye_alt, in float vertex_alt);
vec3 rayleigh_out_shift(in vec3 color, in float outscatter);
//////////////////////
/////// functions /////////
@ -261,32 +266,8 @@ return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
// physically this should be exp(-arg) but for technical reasons we use a sharper cutoff
// for distance > visibility
float fog_func (in float targ)
{
float fade_mix;
// for large altitude > 30 km, we switch to some component of quadratic distance fading to
// create the illusion of improved visibility range
targ = 1.25 * targ; // need to sync with the distance to which terrain is drawn
if (eye_alt < 30000.0)
{return exp(-targ - targ * targ * targ * targ);}
else if (eye_alt < 50000.0)
{
fade_mix = (eye_alt - 30000.0)/20000.0;
return fade_mix * exp(-targ*targ - pow(targ,4.0)) + (1.0 - fade_mix) * exp(-targ - pow(targ,4.0));
}
else
{
return exp(- targ * targ - pow(targ,4.0));
}
}
void main(void)
{
@ -594,6 +575,11 @@ void main(void)
finalColor *= ambient_light;
// Rayleigh color shift due to out-scattering
float rayleigh_length = 0.4 * avisibility * (2.5 - 1.9 * air_pollution)/alt_factor(eye_alt, eye_alt+relPos.z);
float outscatter = 1.0-exp(-dist/rayleigh_length);
finalColor.rgb = rayleigh_out_shift(finalColor.rgb,outscatter);
// here comes the terrain haze model
@ -707,7 +693,7 @@ else
}
transmission = fog_func(transmission_arg);
transmission = fog_func(transmission_arg, eye_alt);
// there's always residual intensity, we should never be driven to zero
if (eqColorFactor < 0.2) eqColorFactor = 0.2;
@ -755,7 +741,11 @@ if (intensity > 0.0) // this needs to be a condition, because otherwise hazeColo
hazeColor = intensity * normalize(mix(hazeColor, shadedFogColor, (1.0-smoothstep(0.5,0.9,eqColorFactor))));
}
float rShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt-340000.0) + 0.1;
float lightIntensity = length(gl_Color.rgb)/1.73 * rShade;
vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
finalColor.rgb = mix(finalColor.rgb, rayleighColor, rayleighStrength);
finalColor.rgb = mix(eqColorFactor * hazeColor * eShade, finalColor.rgb,transmission);