315 lines
9.7 KiB
GLSL
315 lines
9.7 KiB
GLSL
// -*-C++-*-
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// © Vivian Meazza - 2011
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// adapted to Atmospheric Light Scattering by Thorsten Renk 2013
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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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#version 120
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#define fps2kts 0.5925
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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 ambient 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 flogz;
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uniform int colorMode;
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uniform float osg_SimulationTime;
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uniform float Offset, AmpFactor, WindE, WindN, spd, hdg;
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uniform sampler3D Noise;
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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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// 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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float normalize_range(float _val)
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{
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if (_val > 180.0)
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return _val - 360.0;
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else
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return _val;
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}
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void relWind(out float rel_wind_speed_kts, out float rel_wind_from_rad)
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{
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//calculate speed north and east in kts
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float speed_north_kts = cos(radians(hdg)) * spd ;
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float speed_east_kts = sin(radians(hdg)) * spd ;
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//calculate the relative wind speed north and east in kts
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float rel_wind_speed_from_east_kts = WindE*fps2kts + speed_east_kts;
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float rel_wind_speed_from_north_kts = WindN*fps2kts + speed_north_kts;
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//combine relative speeds north and east to get relative windspeed in kts
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rel_wind_speed_kts = sqrt(pow(abs(rel_wind_speed_from_east_kts), 2.0)
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+ pow(abs(rel_wind_speed_from_north_kts), 2.0));
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//calculate the relative wind direction
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float rel_wind_from_deg = degrees(atan(rel_wind_speed_from_east_kts, rel_wind_speed_from_north_kts));
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//rel_wind_from_rad = atan(rel_wind_speed_from_east_kts, rel_wind_speed_from_north_kts);
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float rel_wind = rel_wind_from_deg - hdg;
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rel_wind = normalize_range(rel_wind);
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rel_wind_from_rad = radians(rel_wind);
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}
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void rotationmatrix(in float angle, out mat4 rotmat)
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{
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rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0,
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sin( angle ), cos( angle ), 0.0, 0.0,
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0.0 , 0.0 , 1.0, 0.0,
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0.0 , 0.0 , 0.0, 1.0 );
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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;
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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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mat4 RotationMatrix;
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float relWindspd=0.0;
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float relWinddir=0.0;
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// compute relative wind speed and direction
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relWind (relWindspd, relWinddir);
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// map noise vector
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vec4 noisevec = texture3D(Noise, gl_Vertex.xyz);
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//waving effect
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float tsec = osg_SimulationTime;
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vec4 pos = gl_Vertex;
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vec4 oldpos = gl_Vertex;
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float freq = (10.0 * relWindspd) + 10.0;
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pos.y = sin((pos.x * 5.0 + tsec * freq )/5.0) * 0.5 ;
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pos.y += sin((pos.z * 5.0 + tsec * freq/2.0)/5.0) * 0.125 ;
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pos.y *= pow(pos.x - Offset, 2.0) * AmpFactor;
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//rotate the flag to align with relative wind
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rotationmatrix(-relWinddir, RotationMatrix);
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pos *= RotationMatrix;
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gl_Position = gl_ModelViewProjectionMatrix * pos;
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// logarithmic depth
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flogz = 1.0 + gl_Position.w;
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//do the colour and fog
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vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
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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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// 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
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relPos = gl_Vertex.xyz - ep.xyz;
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// unfortunately, we need the distance in the vertex shader, although the more accurate version
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// is later computed in the fragment shader again
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float dist = length(relPos);
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// altitude of the vertex in question, somehow zero leads to artefacts, so ensure it is at least 100m
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vertex_alt = max(gl_Vertex.z,100.0);
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scattering = ground_scattering + (1.0 - ground_scattering) * smoothstep(hazeLayerAltitude -100.0, hazeLayerAltitude + 100.0, vertex_alt);
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// branch dependent on daytime
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if (terminator < 1000000.0) // the full, sunrise and sunset computation
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{
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// establish coordinates relative to sun position
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vec3 lightFull = (gl_ModelViewMatrixInverse * gl_LightSource[0].position).xyz;
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vec3 lightHorizon = normalize(vec3(lightFull.x,lightFull.y, 0.0));
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// yprime is the distance of the vertex into sun direction
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yprime = -dot(relPos, lightHorizon);
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// this gets an altitude correction, higher terrain gets to see the sun earlier
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yprime_alt = yprime - sqrt(2.0 * EarthRadius * vertex_alt);
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// two times terminator width governs how quickly light fades into shadow
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// now the light-dimming factor
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earthShade = 0.6 * (1.0 - smoothstep(-terminator_width+ terminator, terminator_width + terminator, yprime_alt)) + 0.4;
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// parametrized version of the Flightgear ground lighting function
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lightArg = (terminator-yprime_alt)/100000.0;
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// directional scattering for low sun
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if (lightArg < 10.0)
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{mie_angle = (0.5 * dot(normalize(relPos), normalize(lightFull)) ) + 0.5;}
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else
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{mie_angle = 1.0;}
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light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0);
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light_diffuse.g = light_func(lightArg, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
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light_diffuse.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
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light_diffuse.a = 1.0;
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light_diffuse = light_diffuse * scattering;
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light_ambient.r = light_func(lightArg, 0.236, 0.253, 1.073, 0.572, 0.33);
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light_ambient.g = light_ambient.r * 0.4/0.33;
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light_ambient.b = light_ambient.r * 0.5/0.33;
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light_ambient.a = 1.0;
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// correct ambient light intensity and hue before sunrise
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if (earthShade < 0.5)
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{
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//light_ambient = light_ambient * (0.7 + 0.3 * smoothstep(0.2, 0.5, earthShade));
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intensity = length(light_ambient.xyz);
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light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,earthShade) ));
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light_ambient.rgb = light_ambient.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade));
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intensity = length(light_diffuse.xyz);
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light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.7,earthShade) ));
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}
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// the haze gets the light at the altitude of the haze top if the vertex in view is below
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// but the light at the vertex if the vertex is above
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vertex_alt = max(vertex_alt,hazeLayerAltitude);
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if (vertex_alt > hazeLayerAltitude)
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{
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if (dist > 0.8 * avisibility)
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{
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vertex_alt = mix(vertex_alt, hazeLayerAltitude, smoothstep(0.8*avisibility, avisibility, dist));
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yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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}
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}
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else
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{
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vertex_alt = hazeLayerAltitude;
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yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt);
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}
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}
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else // the faster, full-day version without lightfields
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{
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//vertex_alt = max(gl_Vertex.z,100.0);
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earthShade = 1.0;
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mie_angle = 1.0;
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if (terminator > 3000000.0)
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{light_diffuse = vec4 (1.0, 1.0, 1.0, 0.0);
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light_ambient = vec4 (0.33, 0.4, 0.5, 0.0); }
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else
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{
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lightArg = (terminator/100000.0 - 10.0)/20.0;
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light_diffuse.b = 0.78 + lightArg * 0.21;
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light_diffuse.g = 0.907 + lightArg * 0.091;
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light_diffuse.r = 0.904 + lightArg * 0.092;
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light_diffuse.a = 1.0;
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light_ambient.r = 0.316 + lightArg * 0.016;
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light_ambient.g = light_ambient.r * 0.4/0.33;
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light_ambient.b = light_ambient.r * 0.5/0.33;
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light_ambient.a = 1.0;
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}
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light_diffuse = light_diffuse * scattering;
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yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
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}
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diffuse_term = diffuse_color * light_diffuse;
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vec4 ambient_term = ambient_color * light_ambient;
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// Super hack: if diffuse material alpha is less than 1, assume a
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// transparency animation is at work
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if (gl_FrontMaterial.diffuse.a < 1.0)
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diffuse_term.a = gl_FrontMaterial.diffuse.a;
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else
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diffuse_term.a = gl_Color.a;
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// Another hack for supporting two-sided lighting without using
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// gl_FrontFacing in the fragment shader.
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gl_FrontColor.rgb = ambient_term.rgb; gl_FrontColor.a = 0.0;
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gl_BackColor.rgb = ambient_term.rgb; gl_FrontColor.a = 1.0;
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// fogCoord = abs(ecPosition.z / ecPosition.w);
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//fog_Func(fogType);
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}
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