358 lines
11 KiB
C++
358 lines
11 KiB
C++
// -*-C++-*-
|
|
|
|
#version 120
|
|
|
|
// Atmospheric scattering shader for flightgear
|
|
// Written by Lauri Peltonen (Zan)
|
|
// Implementation of O'Neil's algorithm
|
|
// Ground haze layer added by Thorsten Renk
|
|
|
|
varying vec3 rayleigh;
|
|
varying vec3 mie;
|
|
varying vec3 eye;
|
|
varying vec3 hazeColor;
|
|
varying vec3 viewVector;
|
|
varying float ct;
|
|
varying float cphi;
|
|
varying float delta_z;
|
|
varying float alt;
|
|
varying float earthShade;
|
|
|
|
uniform float overcast;
|
|
uniform float saturation;
|
|
uniform float visibility;
|
|
uniform float avisibility;
|
|
uniform float scattering;
|
|
uniform float terminator;
|
|
uniform float cloud_self_shading;
|
|
uniform float horizon_roughness;
|
|
uniform float ice_hex_col;
|
|
uniform float ice_hex_sheet;
|
|
uniform float parhelic;
|
|
uniform float aurora_strength;
|
|
uniform float aurora_hsize;
|
|
uniform float aurora_vsize;
|
|
uniform float aurora_ray_factor;
|
|
uniform float landing_light1_offset;
|
|
uniform float landing_light2_offset;
|
|
uniform float landing_light3_offset;
|
|
uniform float osg_SimulationTime;
|
|
|
|
uniform int use_searchlight;
|
|
uniform int use_landing_light;
|
|
uniform int use_alt_landing_light;
|
|
|
|
const float EarthRadius = 5800000.0;
|
|
|
|
float Noise2D(in vec2 coord, in float wavelength);
|
|
float fog_backscatter(in float avisibility);
|
|
|
|
vec3 searchlight();
|
|
vec3 landing_light(in float offset, in float offsetv);
|
|
|
|
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 > 30.0) {return e;}
|
|
if (x < -15.0) {return 0.0;}
|
|
|
|
return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
|
|
}
|
|
|
|
float miePhase(in float cosTheta, in float g)
|
|
{
|
|
float g2 = g*g;
|
|
float a = 1.5 * (1.0 - g2);
|
|
float b = (2.0 + g2);
|
|
float c = 1.0 + cosTheta*cosTheta;
|
|
float d = pow(1.0 + g2 - 2.0 * g * cosTheta, 0.6667);
|
|
|
|
return (a*c) / (b*d);
|
|
}
|
|
|
|
float rayleighPhase(in float cosTheta)
|
|
{
|
|
//return 1.5 * (1.0 + cosTheta*cosTheta);
|
|
return 1.5 * (2.0 + 0.5*cosTheta*cosTheta);
|
|
}
|
|
|
|
|
|
void main()
|
|
{
|
|
|
|
|
|
vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
|
|
float cosTheta = dot(normalize(eye), gl_LightSource[0].position.xyz);
|
|
|
|
// some geometry
|
|
|
|
vec3 nView = normalize(viewVector);
|
|
vec3 lightFull = normalize((gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz);
|
|
float calpha = dot(lightFull, nView);
|
|
float cbeta = dot ( normalize(lightFull.xy), normalize(nView.xy));
|
|
float costheta = ct;
|
|
|
|
// some noise
|
|
|
|
float hNoise_03 = Noise2D(vec2(0.0,cphi), 0.3);
|
|
float hNoiseAurora = Noise2D(vec2(0.001 * osg_SimulationTime,cphi + nView.x + nView.y), 0.07) * 0.2 * aurora_ray_factor;
|
|
|
|
// position of the horizon line
|
|
|
|
float lAltitude = alt + delta_z;
|
|
float radiusEye = EarthRadius + alt;
|
|
float radiusLayer = EarthRadius + lAltitude;
|
|
float cthorizon;
|
|
float ctterrain;
|
|
|
|
if (radiusEye > radiusLayer) cthorizon = -sqrt(radiusEye * radiusEye - radiusLayer * radiusLayer)/radiusEye;
|
|
else cthorizon = sqrt(radiusLayer * radiusLayer - radiusEye * radiusEye)/radiusLayer;
|
|
|
|
ctterrain = -sqrt(radiusEye * radiusEye - EarthRadius * EarthRadius)/radiusEye;
|
|
|
|
vec3 color = rayleigh * rayleighPhase(cosTheta);
|
|
color += mie * miePhase(cosTheta, -0.8);
|
|
|
|
vec3 black = vec3(0.0,0.0,0.0);
|
|
|
|
|
|
float ovc = overcast;
|
|
|
|
|
|
float sat = 1.0 - ((1.0 - saturation) * 2.0);
|
|
if (sat < 0.3) sat = 0.3;
|
|
|
|
if (color.r > 0.58) color.r = 1.0 - exp(-1.5 * color.r);
|
|
if (color.g > 0.58) color.g = 1.0 - exp(-1.5 * color.g);
|
|
if (color.b > 0.58) color.b = 1.0 - exp(-1.5 * color.b);
|
|
|
|
|
|
|
|
// Aurora Borealis / Australis
|
|
|
|
vec3 direction = vec3 (1.0, 0.0, 0.0);
|
|
|
|
float hArg = dot(nView, direction);
|
|
|
|
|
|
float aurora_v = smoothstep(0.2 - 0.6 * aurora_vsize * (1.0 - 0.8* aurora_ray_factor) , 0.2 , costheta + hNoiseAurora) * (1.0- smoothstep(0.3, 0.3 + aurora_vsize, costheta + hNoiseAurora));
|
|
aurora_v *= (1.0 + 5.0 * aurora_ray_factor * (1.0 -smoothstep(0.2 - 0.6 * aurora_vsize * (1.0 - 0.8* aurora_ray_factor), 0.3, costheta + hNoiseAurora)));
|
|
|
|
float aurora_h = smoothstep(1.0 - aurora_hsize, 1.0, hArg);
|
|
float aurora_time = 0.01 * osg_SimulationTime;
|
|
|
|
vec3 auroraBaseColor = vec3 (0.0, 0.2, 0.1);
|
|
|
|
float aurora_ray = mix(1.0, Noise2D(vec2(cbeta, 0.01 * aurora_time), 0.001), aurora_ray_factor);
|
|
|
|
float aurora_visible_strength = 0.3 + 0.7 * Noise2D(vec2(costheta + aurora_time, 0.5 * nView.x + 0.3 * nView.y + aurora_time), 0.1) ;
|
|
aurora_visible_strength *= aurora_ray;
|
|
float aurora_fade_in = 1.0 - smoothstep(0.1, 0.2, length(color.rgb));
|
|
|
|
|
|
|
|
color.rgb += auroraBaseColor * aurora_v * aurora_h * aurora_fade_in * aurora_visible_strength * aurora_strength;
|
|
|
|
// fog computations for a ground haze layer, extending from zero to lAltitude
|
|
|
|
float transmission;
|
|
float vAltitude;
|
|
float delta_zv;
|
|
|
|
|
|
|
|
float vis = min(visibility, avisibility);
|
|
|
|
|
|
if (delta_z > 0.0) // we're inside the layer
|
|
{
|
|
if (costheta>0.0 + ctterrain) // looking up, view ray intersecting upper layer edge
|
|
{
|
|
transmission = exp(-min((delta_z/max(costheta,0.1)),25000.0)/vis);
|
|
//transmission = 1.0;
|
|
vAltitude = min(vis * costheta, delta_z);
|
|
delta_zv = delta_z - vAltitude;
|
|
}
|
|
|
|
else // looking down, view range intersecting terrain (which may not be drawn)
|
|
{
|
|
transmission = exp(alt/vis/costheta);
|
|
vAltitude = min(-vis * costheta, alt);
|
|
delta_zv = delta_z + vAltitude;
|
|
}
|
|
}
|
|
else // we see the layer from above
|
|
{
|
|
if (costheta < 0.0 + cthorizon)
|
|
{
|
|
transmission = exp(-min(lAltitude/abs(costheta),25000.0)/vis);
|
|
transmission = transmission * exp(-alt/avisibility/abs(costheta));
|
|
transmission = 1.0 - (1.0 - transmission) * smoothstep(0+cthorizon, -0.02+cthorizon, costheta);
|
|
vAltitude = min(lAltitude, -vis * costheta);
|
|
delta_zv = vAltitude;
|
|
}
|
|
else
|
|
{
|
|
transmission = 1.0;
|
|
delta_zv = 0.0;
|
|
}
|
|
}
|
|
|
|
// combined intensity reduction by cloud shading and fog self-shading, corrected for Weber-Fechner perception law
|
|
float eqColorFactor = 1.0 - 0.1 * delta_zv/vis - (1.0 - min(scattering,cloud_self_shading));
|
|
|
|
|
|
// there's always residual intensity, we should never be driven to zero
|
|
if (eqColorFactor < 0.2) eqColorFactor = 0.2;
|
|
|
|
|
|
// postprocessing of haze color
|
|
vec3 hColor = hazeColor;
|
|
|
|
|
|
// high altitude desaturation
|
|
float intensity = length(hColor);
|
|
hColor = intensity * normalize (mix(hColor, intensity * vec3 (1.0,1.0,1.0), 0.7 * smoothstep(5000.0, 50000.0, alt)));
|
|
|
|
hColor = clamp(hColor,0.0,1.0);
|
|
|
|
// blue hue
|
|
hColor.x = 0.83 * hColor.x;
|
|
hColor.y = 0.9 * hColor.y;
|
|
|
|
|
|
|
|
// further blueshift when in shadow, either cloud shadow, or self-shadow or Earth shadow, dependent on indirect
|
|
// light
|
|
|
|
float fade_out = max(0.65 - 0.3 *overcast, 0.45);
|
|
intensity = length(hColor);
|
|
vec3 oColor = hColor;
|
|
oColor = intensity * normalize(mix(oColor, shadedFogColor, (smoothstep(0.1,1.0,ovc))));
|
|
|
|
// ice crystal halo
|
|
|
|
float sun_altitude = dot (lightFull, vec3 (0.0, 0.0, 1.0));
|
|
float view_altitude = dot(nView, vec3 (0.0, 0.0, 1.0));
|
|
|
|
//float halo_ring_enhancement = smoothstep (0.88, 0.927, calpha) * (1.0 - smoothstep(0.927, 0.98, calpha));
|
|
float halo_ring_enhancement = smoothstep (0.88, 0.927, calpha) * (1.0 - smoothstep(0.927, 0.94, calpha));
|
|
halo_ring_enhancement *= halo_ring_enhancement;
|
|
|
|
|
|
// parhelic circle
|
|
|
|
float parhelic_circle_enhancement = 0.3 * smoothstep (sun_altitude-0.01, sun_altitude, view_altitude) * (1.0 - smoothstep(sun_altitude, sun_altitude+ 0.01, view_altitude));
|
|
|
|
parhelic_circle_enhancement += 0.8 * smoothstep (sun_altitude-0.08, sun_altitude, view_altitude) * (1.0 - smoothstep(sun_altitude, sun_altitude+ 0.08, view_altitude));
|
|
|
|
parhelic_circle_enhancement *= parhelic * (0.2 + 0.8 * smoothstep(0.5, 1.0, cbeta));
|
|
|
|
// sundogs
|
|
|
|
float side_sun_enhancement = smoothstep (sun_altitude-0.03, sun_altitude, view_altitude) * (1.0 - smoothstep(sun_altitude, sun_altitude+ 0.03, view_altitude));
|
|
|
|
side_sun_enhancement *= halo_ring_enhancement * halo_ring_enhancement * ice_hex_sheet;
|
|
|
|
// pillar
|
|
|
|
float pillar_enhancement = smoothstep (sun_altitude-0.1, sun_altitude, view_altitude) * (1.0 - smoothstep(sun_altitude, sun_altitude+ 0.22, view_altitude));
|
|
float beta_thickness = 0.6 * smoothstep(0.999, 1.0, cbeta);
|
|
beta_thickness += 0.8 * smoothstep(0.99998, 1.0, cbeta);
|
|
pillar_enhancement *= beta_thickness * beta_thickness * smoothstep(0.99, 1.0, calpha) * ice_hex_col;
|
|
|
|
|
|
|
|
float scattering_enhancements = 0.25 * halo_ring_enhancement * ovc;
|
|
scattering_enhancements += side_sun_enhancement *0.4 * (1.0 - smoothstep(0.6, 0.95, transmission));
|
|
scattering_enhancements += pillar_enhancement *0.25 * (1.0 - smoothstep(0.7, 1.0, transmission));
|
|
scattering_enhancements += parhelic_circle_enhancement * 0.2 * (1.0 - smoothstep(0.7, 1.0, transmission));
|
|
|
|
|
|
color.rgb += vec3(1.0, 1.0, 1.0) * (5.0-4.0* earthShade) * scattering_enhancements * hazeColor;
|
|
|
|
oColor = clamp(oColor,0.0,1.0);
|
|
color = ovc * mix(color, oColor * earthShade ,smoothstep(-0.1+ctterrain, 0.0+ctterrain, ct)) + (1.0-ovc) * color;
|
|
|
|
|
|
hColor = intensity * normalize(mix(hColor, 1.5 * shadedFogColor, 1.0 -smoothstep(0.25, fade_out,earthShade) ));
|
|
hColor = intensity * normalize(mix(hColor, shadedFogColor, (1.0 - smoothstep(0.5,0.9,eqColorFactor))));
|
|
hColor = hColor * earthShade;
|
|
|
|
// accounting for overcast and saturation
|
|
|
|
|
|
|
|
color = sat * color + (1.0 - sat) * mix(color, black, smoothstep(0.4+cthorizon,0.2+cthorizon,ct));
|
|
|
|
|
|
// the terrain below the horizon gets drawn in one optical thickness
|
|
vec3 terrainHazeColor = eqColorFactor * hColor;
|
|
|
|
// determine a visibility-dependent angle for how smoothly the haze blends over the skydome
|
|
|
|
float hazeBlendAngle = max(0.01,1000.0/avisibility + 0.3 * (1.0 - smoothstep(5000.0, 30000.0, avisibility)));
|
|
float altFactor = smoothstep(-300.0, 0.0, delta_z);
|
|
float altFactor2 = 0.2 + 0.8 * smoothstep(-3000.0, 0.0, delta_z);
|
|
hazeBlendAngle = hazeBlendAngle + 0.1 * altFactor;
|
|
hazeBlendAngle = hazeBlendAngle + (1.0-horizon_roughness) * altFactor2 * 0.1 * hNoise_03;
|
|
|
|
terrainHazeColor = clamp(terrainHazeColor,0.0,1.0);
|
|
|
|
|
|
// don't let the light fade out too rapidly
|
|
float lightArg = (terminator + 200000.0)/100000.0;
|
|
float minLightIntensity = min(0.2,0.16 * lightArg + 0.5);
|
|
vec3 minLight = minLightIntensity * vec3 (0.2, 0.3, 0.4);
|
|
|
|
// this is for the bare Rayleigh and Mie sky, highly altitude dependent
|
|
color.rgb = max(color.rgb, minLight.rgb * (1.0- min(alt/100000.0,1.0)) * (1.0 - costheta));
|
|
|
|
// this is for the terrain drawn
|
|
terrainHazeColor = max(terrainHazeColor.rgb, minLight.rgb);
|
|
|
|
color = mix(color, terrainHazeColor ,smoothstep(hazeBlendAngle + ctterrain, 0.0+ctterrain, ct));
|
|
|
|
|
|
// add the brightening of fog by lights
|
|
|
|
vec3 secondary_light = vec3 (0.0,0.0,0.0);
|
|
|
|
if (use_searchlight == 1)
|
|
{
|
|
secondary_light.rgb += searchlight();
|
|
}
|
|
if (use_landing_light == 1)
|
|
{
|
|
secondary_light += landing_light(landing_light1_offset, landing_light3_offset);
|
|
}
|
|
if (use_alt_landing_light == 1)
|
|
{
|
|
secondary_light += landing_light(landing_light2_offset, landing_light3_offset);
|
|
}
|
|
|
|
|
|
|
|
|
|
// mix fog the skydome with the right amount of haze
|
|
|
|
hColor *= eqColorFactor;
|
|
hColor = max(hColor.rgb, minLight.rgb);
|
|
|
|
hColor = clamp(hColor,0.0,1.0);
|
|
|
|
color = mix(hColor+secondary_light * fog_backscatter(avisibility),color, transmission);
|
|
|
|
|
|
|
|
gl_FragColor = vec4(color, 1.0);
|
|
gl_FragDepth = 0.1;
|
|
|
|
//gl_FragColor.rgb *= aurora_v * aurora_h;
|
|
|
|
//float test = dot (normalize(relVector), vec3 (0.0, 0.0, 1.0));
|
|
//gl_FragColor = vec4(test, test, test, 1.0);
|
|
}
|
|
|