226 lines
6.4 KiB
GLSL
226 lines
6.4 KiB
GLSL
// This shader is mostly an adaptation of the shader found at
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// http://www.bonzaisoftware.com/water_tut.html and its glsl conversion
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// available at http://forum.bonzaisoftware.com/viewthread.php?tid=10
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// © Michael Horsch - 2005
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// Major update and revisions - 2011-10-07
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// © Emilian Huminiuc and Vivian Meazza
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#version 120
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varying vec4 waterTex1;
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varying vec4 waterTex2;
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varying vec4 waterTex4;
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//varying vec4 ecPosition;
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varying vec3 relPos;
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varying vec3 specular_light;
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varying vec3 viewerdir;
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varying vec3 lightdir;
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//varying vec3 normal;
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varying float earthShade;
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varying float yprime_alt;
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varying float mie_angle;
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uniform float osg_SimulationTime;
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uniform float WindE, WindN;
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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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// 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 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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////fog "include"////////
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// uniform int fogType;
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//
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// void fog_Func(int type);
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/////////////////////////
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/////// functions /////////
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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(void)
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{
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mat4 RotationMatrix;
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// vec3 N = normalize(gl_Normal);
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// normal = N;
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vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex;
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viewerdir = vec3(gl_ModelViewMatrixInverse[3]) - vec3(gl_Vertex);
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lightdir = normalize(vec3(gl_ModelViewMatrixInverse * gl_LightSource[0].position));
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waterTex4 = vec4( ecPosition.xzy, 0.0 );
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vec4 t1 = vec4(0.0, osg_SimulationTime * 0.005217, 0.0, 0.0);
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vec4 t2 = vec4(0.0, osg_SimulationTime * -0.0012, 0.0, 0.0);
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float Angle;
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float windFactor = sqrt(WindE * WindE + WindN * WindN) * 0.05;
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if (WindN == 0.0 && WindE == 0.0) {
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Angle = 0.0;
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}else{
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Angle = atan(-WindN, WindE) - atan(1.0);
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}
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rotationmatrix(Angle, RotationMatrix);
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waterTex1 = gl_MultiTexCoord0 * RotationMatrix - t1 * windFactor;
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rotationmatrix(Angle, RotationMatrix);
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waterTex2 = gl_MultiTexCoord0 * RotationMatrix - t2 * windFactor;
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// fog_Func(fogType);
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gl_Position = ftransform();
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// here start computations for the haze layer
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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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// 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
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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 = 0.5 + 0.5 * ground_scattering + 0.5* (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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vec3 lightHorizon = normalize(vec3(lightdir.x,lightdir.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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specular_light.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0);
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specular_light.g = light_func(lightArg, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0);
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specular_light.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0);
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specular_light = specular_light * scattering;
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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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intensity = length(specular_light.rgb);
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specular_light.xyz = intensity * normalize(mix(specular_light.xyz, vec3 (0.45, 0.6, 0.8), 1.0 -smoothstep(0.1, 0.7,earthShade) ));
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}
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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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{mie_angle = (0.5 * dot(normalize(relPos), lightdir) ) + 0.5;}
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else
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{mie_angle = 1.0;}
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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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{specular_light = vec3 (1.0, 1.0, 1.0);}
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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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specular_light.b = 0.78 + lightArg * 0.21;
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specular_light.g = 0.907 + lightArg * 0.091;
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specular_light.r = 0.904 + lightArg * 0.092;
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}
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specular_light = specular_light * scattering;
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yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude);
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}
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}
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