Spaceflight shader effect with altitude dependent mixture of ambient and diffuse light
This commit is contained in:
Thorsten Renk
parent
b4d16682ce
commit
5fba8d301f
4 changed files with 616 additions and 4 deletions
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@ -103,10 +103,10 @@
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<use>vertex-program-two-side</use>
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</vertex-program-two-side>
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<program>
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<vertex-shader>Shaders/generic-ALS-base.vert</vertex-shader>
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<fragment-shader>Shaders/model-ALS-base.frag</fragment-shader>
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<fragment-shader>Shaders/hazes.frag</fragment-shader>
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<fragment-shader>Shaders/secondary_lights.frag</fragment-shader>
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<vertex-shader n="1">Shaders/generic-ALS-base.vert</vertex-shader>
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<fragment-shader n="1">Shaders/model-ALS-base.frag</fragment-shader>
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<fragment-shader n="2">Shaders/hazes.frag</fragment-shader>
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<fragment-shader n="3">Shaders/secondary_lights.frag</fragment-shader>
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</program>
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<uniform>
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<name>visibility</name>
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18
Effects/space.eff
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18
Effects/space.eff
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<?xml version="1.0" encoding="utf-8"?>
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<!-- Altitude-dependent scattered light -->
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<PropertyList>
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<name>Effects/space</name>
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<inherits-from>Effects/model-default</inherits-from>
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<technique n="5">
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<pass>
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<program>
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<vertex-shader n="1">Shaders/space-ALS-base.vert</vertex-shader>
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<fragment-shader n="1">Shaders/space-ALS-base.frag</fragment-shader>
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<fragment-shader n="2">Shaders/hazes.frag</fragment-shader>
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<fragment-shader n="3">Shaders/secondary_lights.frag</fragment-shader>
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</program>
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</pass>
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</technique>
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</PropertyList>
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330
Shaders/space-ALS-base.frag
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Shaders/space-ALS-base.frag
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// -*-C++-*-
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// written by Thorsten Renk, Oct 2011, based on default.frag
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// Ambient term comes in gl_Color.rgb.
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varying vec4 diffuse_term;
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varying vec3 normal;
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varying vec3 relPos;
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uniform sampler2D texture;
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varying float yprime_alt;
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varying float mie_angle;
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uniform float visibility;
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uniform float avisibility;
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uniform float scattering;
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uniform float terminator;
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uniform float terrain_alt;
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uniform float hazeLayerAltitude;
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uniform float overcast;
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uniform float eye_alt;
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uniform float cloud_self_shading;
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uniform float air_pollution;
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uniform float landing_light1_offset;
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uniform float landing_light2_offset;
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uniform int quality_level;
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uniform int tquality_level;
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uniform int use_searchlight;
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uniform int use_landing_light;
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uniform int use_alt_landing_light;
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const float EarthRadius = 5800000.0;
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const float terminator_width = 200000.0;
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float alt;
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float eShade;
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float fog_func (in float targ, in float alt);
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float rayleigh_in_func(in float dist, in float air_pollution, in float avisibility, in float eye_alt, in float vertex_alt);
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float alt_factor(in float eye_alt, in float vertex_alt);
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float light_distance_fading(in float dist);
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float fog_backscatter(in float avisibility);
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vec3 rayleigh_out_shift(in vec3 color, in float outscatter);
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vec3 get_hazeColor(in float light_arg);
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vec3 searchlight();
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vec3 landing_light(in float offset);
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float luminance(vec3 color)
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{
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return dot(vec3(0.212671, 0.715160, 0.072169), color);
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}
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float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
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{
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x = x - 0.5;
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// use the asymptotics to shorten computations
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if (x > 30.0) {return e;}
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if (x < -15.0) {return 0.0;}
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return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
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}
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// this determines how light is attenuated in the distance
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// physically this should be exp(-arg) but for technical reasons we use a sharper cutoff
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// for distance > visibility
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void main()
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{
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vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
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// this is taken from default.frag
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vec3 n;
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float NdotL, NdotHV, fogFactor;
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vec4 color = gl_Color;
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vec3 lightDir = gl_LightSource[0].position.xyz;
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vec3 halfVector = gl_LightSource[0].halfVector.xyz;
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vec4 texel;
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vec4 fragColor;
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vec4 specular = vec4(0.0);
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float intensity;
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float effective_scattering = min(scattering, cloud_self_shading);
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eShade = 1.0 - 0.9 * smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt);
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vec4 light_specular = gl_LightSource[0].specular * (eShade - 0.1);
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// If gl_Color.a == 0, this is a back-facing polygon and the
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// normal should be reversed.
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n = (2.0 * gl_Color.a - 1.0) * normal;
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n = normalize(n);
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NdotL = dot(n, lightDir);
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if (NdotL > 0.0) {
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color += diffuse_term * NdotL;
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NdotHV = max(dot(n, halfVector), 0.0);
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if (gl_FrontMaterial.shininess > 0.0)
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specular.rgb = (gl_FrontMaterial.specular.rgb
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* light_specular.rgb
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* pow(NdotHV, gl_FrontMaterial.shininess));
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}
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//vec3 up = (gl_ModelViewMatrix * vec4(0.0,0.0,1.0,0.0)).xyz;
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//vec3 sky_blue = vec3 (0.17, 0.52, 0.87);
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//NdotL = dot(n, -up);
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//if (NdotL > 0.0)
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//{
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//color.rgb += sky_blue * NdotL;
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//}
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color.a = diffuse_term.a;
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// This shouldn't be necessary, but our lighting becomes very
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// saturated. Clamping the color before modulating by the texture
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// is closer to what the OpenGL fixed function pipeline does.
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color = clamp(color, 0.0, 1.0);
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float dist = length(relPos);
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vec3 secondary_light = vec3 (0.0,0.0,0.0);
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if ((quality_level > 5) && (tquality_level > 5))
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{
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if (use_searchlight == 1)
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{
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secondary_light += searchlight();
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}
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if (use_landing_light == 1)
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{
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secondary_light += landing_light(landing_light1_offset);
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}
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if (use_alt_landing_light == 1)
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{
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secondary_light += landing_light(landing_light2_offset);
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}
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if (dist > 2.0) // we don't want to light the cockpit...
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{color.rgb +=secondary_light * light_distance_fading(dist);}
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}
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texel = texture2D(texture, gl_TexCoord[0].st);
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fragColor = color * texel + specular;
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float lightArg = (terminator-yprime_alt)/100000.0;
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vec3 hazeColor = get_hazeColor(lightArg);
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// Rayleigh color shift due to in-scattering
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if ((quality_level > 5) && (tquality_level > 5))
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{
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float rayleigh_length = 0.5 * avisibility * (2.5 - 1.9 * air_pollution)/alt_factor(eye_alt, eye_alt+relPos.z);
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float outscatter = 1.0-exp(-dist/rayleigh_length);
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fragColor.rgb = rayleigh_out_shift(fragColor.rgb,outscatter);
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float rShade = 1.0 - 0.9 * smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt + 420000.0);
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float lightIntensity = length(hazeColor * effective_scattering) * rShade;
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vec3 rayleighColor = vec3 (0.17, 0.52, 0.87) * lightIntensity;
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float rayleighStrength = rayleigh_in_func(dist, air_pollution, avisibility/max(lightIntensity,0.05), eye_alt, eye_alt + relPos.z);
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fragColor.rgb = mix(fragColor.rgb, rayleighColor,rayleighStrength);
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}
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// here comes the terrain haze model
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float delta_z = hazeLayerAltitude - eye_alt;
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float mvisibility = min(visibility, avisibility);
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if (dist > 0.04 * mvisibility)
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{
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alt = eye_alt;
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float transmission;
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float vAltitude;
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float delta_zv;
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float H;
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float distance_in_layer;
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float transmission_arg;
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// angle with horizon
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float ct = dot(vec3(0.0, 0.0, 1.0), relPos)/dist;
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// we solve the geometry what part of the light path is attenuated normally and what is through the haze layer
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if (delta_z > 0.0) // we're inside the layer
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{
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if (ct < 0.0) // we look down
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{
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distance_in_layer = dist;
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vAltitude = min(distance_in_layer,mvisibility) * ct;
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delta_zv = delta_z - vAltitude;
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}
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else // we may look through upper layer edge
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{
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H = dist * ct;
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if (H > delta_z) {distance_in_layer = dist/H * delta_z;}
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else {distance_in_layer = dist;}
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vAltitude = min(distance_in_layer,visibility) * ct;
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delta_zv = delta_z - vAltitude;
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}
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}
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else // we see the layer from above, delta_z < 0.0
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{
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H = dist * -ct;
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if (H < (-delta_z)) // we don't see into the layer at all, aloft visibility is the only fading
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{
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distance_in_layer = 0.0;
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delta_zv = 0.0;
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}
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else
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{
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vAltitude = H + delta_z;
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distance_in_layer = vAltitude/H * dist;
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vAltitude = min(distance_in_layer,visibility) * (-ct);
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delta_zv = vAltitude;
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}
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}
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// ground haze cannot be thinner than aloft visibility in the model,
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// so we need to use aloft visibility otherwise
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transmission_arg = (dist-distance_in_layer)/avisibility;
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float eqColorFactor;
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//float scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, relPos.z + eye_alt);
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if (visibility < avisibility)
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{
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transmission_arg = transmission_arg + (distance_in_layer/visibility);
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// this combines the Weber-Fechner intensity
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eqColorFactor = 1.0 - 0.1 * delta_zv/visibility - (1.0 -effective_scattering);
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}
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else
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{
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transmission_arg = transmission_arg + (distance_in_layer/avisibility);
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// this combines the Weber-Fechner intensity
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eqColorFactor = 1.0 - 0.1 * delta_zv/avisibility - (1.0 -effective_scattering);
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}
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transmission = fog_func(transmission_arg, alt);
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// there's always residual intensity, we should never be driven to zero
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if (eqColorFactor < 0.2) eqColorFactor = 0.2;
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// Mie-like factor
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if (lightArg < 10.0)
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{intensity = length(hazeColor);
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float mie_magnitude = 0.5 * smoothstep(350000.0, 150000.0, terminator-sqrt(2.0 * EarthRadius * terrain_alt));
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hazeColor = intensity * ((1.0 - mie_magnitude) + mie_magnitude * mie_angle) * normalize(mix(hazeColor, vec3 (0.5, 0.58, 0.65), mie_magnitude * (0.5 - 0.5 * mie_angle)) );
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}
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// high altitude desaturation of the haze color
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intensity = length(hazeColor);
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hazeColor = intensity * normalize (mix(hazeColor, intensity * vec3 (1.0,1.0,1.0), 0.7* smoothstep(5000.0, 50000.0, alt)));
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// blue hue of haze
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hazeColor.x = hazeColor.x * 0.83;
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hazeColor.y = hazeColor.y * 0.9;
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// additional blue in indirect light
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float fade_out = max(0.65 - 0.3 *overcast, 0.45);
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intensity = length(hazeColor);
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hazeColor = intensity * normalize(mix(hazeColor, 1.5* shadedFogColor, 1.0 -smoothstep(0.25, fade_out,eShade) ));
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// change haze color to blue hue for strong fogging
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//intensity = length(hazeColor);
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hazeColor = intensity * normalize(mix(hazeColor, shadedFogColor, (1.0-smoothstep(0.5,0.9,eqColorFactor))));
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// reduce haze intensity when looking at shaded surfaces, only in terminator region
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float shadow = mix( min(1.0 + dot(normal,lightDir),1.0), 1.0, 1.0-smoothstep(0.1, 0.4, transmission));
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hazeColor = mix(shadow * hazeColor, hazeColor, 0.3 + 0.7* smoothstep(250000.0, 400000.0, terminator));
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// don't let the light fade out too rapidly
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lightArg = (terminator + 200000.0)/100000.0;
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float minLightIntensity = min(0.2,0.16 * lightArg + 0.5);
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vec3 minLight = minLightIntensity * vec3 (0.2, 0.3, 0.4);
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hazeColor *= eqColorFactor * eShade;
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hazeColor.rgb = max(hazeColor.rgb, minLight.rgb);
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// determine the right mix of transmission and haze
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fragColor.rgb = mix(hazeColor + secondary_light * fog_backscatter(mvisibility), fragColor.rgb,transmission);
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}
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gl_FragColor = fragColor;
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}
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264
Shaders/space-ALS-base.vert
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264
Shaders/space-ALS-base.vert
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@ -0,0 +1,264 @@
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// -*-C++-*-
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// Shader that uses OpenGL state values to do per-pixel lighting
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//
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// The only light used is gl_LightSource[0], which is assumed to be
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// directional.
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//
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// Diffuse colors come from the gl_Color, ambient from the material. This is
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// equivalent to osg::Material::DIFFUSE.
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// Haze part added by Thorsten Renk, Oct. 2011
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#define MODE_OFF 0
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#define MODE_DIFFUSE 1
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#define MODE_AMBIENT_AND_DIFFUSE 2
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// The constant term of the lighting equation that doesn't depend on
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// the surface normal is passed in gl_{Front,Back}Color. The alpha
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// component is set to 1 for front, 0 for back in order to work around
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// bugs with gl_FrontFacing in the fragment shader.
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varying vec4 diffuse_term;
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varying vec3 normal;
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varying vec3 relPos;
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varying float yprime_alt;
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varying float mie_angle;
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varying float alt_factor;
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uniform int colorMode;
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uniform float hazeLayerAltitude;
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uniform float terminator;
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uniform float terrain_alt;
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uniform float avisibility;
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uniform float visibility;
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uniform float overcast;
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uniform float ground_scattering;
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uniform float moonlight;
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uniform float eye_alt;
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// This is the value used in the skydome scattering shader - use the same here for consistency?
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const float EarthRadius = 5800000.0;
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const float terminator_width = 200000.0;
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float earthShade;
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float light_func (in float x, in float a, in float b, in float c, in float d, in float e)
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{
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//x = x - 0.5;
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// use the asymptotics to shorten computations
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if (x < -15.0) {return 0.0;}
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return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
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}
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void main()
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{
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vec4 light_diffuse;
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vec4 light_ambient;
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vec3 shadedFogColor = vec3(0.55, 0.67, 0.88);
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vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight;
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//float yprime_alt;
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float yprime;
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float lightArg;
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float intensity;
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float vertex_alt;
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float scattering;
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// this code is copied from default.vert
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//vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
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gl_Position = ftransform();
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gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
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normal = gl_NormalMatrix * gl_Normal;
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vec4 ambient_color, diffuse_color;
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if (colorMode == MODE_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_FrontMaterial.ambient;
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} else if (colorMode == MODE_AMBIENT_AND_DIFFUSE) {
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diffuse_color = gl_Color;
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ambient_color = gl_Color;
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} else {
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diffuse_color = gl_FrontMaterial.diffuse;
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ambient_color = gl_FrontMaterial.ambient;
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}
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// here start computations for the haze layer
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// we need several geometrical quantities
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// first current altitude of eye position in model space
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vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0);
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// 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.rgb);
|
||||
|
||||
light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.4, 0.8,earthShade) ));
|
||||
|
||||
|
||||
intensity = length(light_diffuse.rgb);
|
||||
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);
|
||||
}
|
||||
|
||||
// at high altitude, the light gets de-saturated and the ambient channel dies out
|
||||
// whereas the diffuse channel is enhanced
|
||||
|
||||
alt_factor = smoothstep(10000.0, 100000.0, eye_alt);
|
||||
float ambient_reduction = 0.25 + 0.75 * (1.0-alt_factor);
|
||||
float diffuse_enhancement = 1.0 + 1.0 * (1.0 - ambient_reduction);
|
||||
|
||||
light_ambient.rgb = light_ambient.rgb * ambient_reduction;
|
||||
light_diffuse.rgb = light_diffuse.rgb * diffuse_enhancement;
|
||||
light_ambient.rgb = light_ambient.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade));
|
||||
|
||||
vec3 sky_blue = normalize (vec3 (0.17, 0.52, 0.87));
|
||||
intensity = length(light_ambient.rgb);
|
||||
light_ambient.rgb = mix(light_ambient.rgb, intensity * sky_blue, alt_factor);
|
||||
|
||||
intensity = length(light_diffuse.rgb);
|
||||
light_diffuse.rgb = mix(light_diffuse.rgb, intensity * vec3 (1.0,1.0,1.0), alt_factor);
|
||||
|
||||
// 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;
|
||||
|
||||
}
|
||||
|
||||
|
||||
|
||||
|
||||
Loading…
Add table
Reference in a new issue