// This shader is mostly an adaptation of the shader found at // http://www.bonzaisoftware.com/water_tut.html and its glsl conversion // available at http://forum.bonzaisoftware.com/viewthread.php?tid=10 // © Michael Horsch - 2005 // Major update and revisions - 2011-10-07 // © Emilian Huminiuc and Vivian Meazza // Optimisation - 2012-5-05 // © Emilian Huminiuc and Vivian Meazza // Ported to the Atmospheric Light Scattering Framework // by Thorsten Renk, Aug. 2013 #version 120 #define fps2kts 0.5925 varying vec4 waterTex1; varying vec4 waterTex2; varying vec3 relPos; varying vec3 rawPos; varying vec3 viewerdir; varying vec3 lightdir; varying vec3 normal; varying float steepness; varying float earthShade; varying float yprime_alt; varying float mie_angle; varying float flogz; uniform float osg_SimulationTime; uniform float WindE, WindN, spd, hdg; uniform float hazeLayerAltitude; uniform float terminator; uniform float terrain_alt; uniform float avisibility; uniform float visibility; uniform float overcast; uniform float ground_scattering; uniform mat4 osg_ViewMatrixInverse; vec3 specular_light; // This is the value used in the skydome scattering shader - use the same here for consistency? const float EarthRadius = 5800000.0; const float terminator_width = 200000.0; ///////////////////////// /////// functions ///////// void relWind(out float rel_wind_speed_kts, float rel_wind_from_deg) { //calculate the carrier speed north and east in kts float speed_north_kts = cos(radians(hdg)) * spd ; float speed_east_kts = sin(radians(hdg)) * spd ; //calculate the relative wind speed north and east in kts float rel_wind_speed_from_east_kts = WindE*fps2kts + speed_east_kts; float rel_wind_speed_from_north_kts = WindN*fps2kts + speed_north_kts; //combine relative speeds north and east to get relative windspeed in kts rel_wind_speed_kts = sqrt((rel_wind_speed_from_east_kts * rel_wind_speed_from_east_kts) + (rel_wind_speed_from_north_kts * rel_wind_speed_from_north_kts)); //calculate the relative wind direction rel_wind_from_deg = degrees(atan(rel_wind_speed_from_east_kts, rel_wind_speed_from_north_kts)); } 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 < -15.0) {return 0.0;} return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d)); } void main(void) { float relWindspd=0; float relWinddir=0; //compute relative wind speed and direction relWind (relWindspd, relWinddir); vec3 N = normalize(gl_Normal); normal = N; viewerdir = vec3(gl_ModelViewMatrixInverse[3]) - vec3(gl_Vertex); lightdir = normalize(vec3(gl_ModelViewMatrixInverse * gl_LightSource[0].position)); vec3 shadedFogColor = vec3(0.55, 0.67, 0.88); rawPos = (osg_ViewMatrixInverse *gl_ModelViewMatrix * gl_Vertex).xyz; vec4 t1 = vec4(osg_SimulationTime*0.005217, 0.0, 0.0, 0.0); vec4 t2 = vec4(osg_SimulationTime*-0.0012, 0.0, 0.0, 0.0); float windFactor = -relWindspd * 0.1; // float windFactor = sqrt(pow(abs(WindE),2)+pow(abs(WindN),2)) * 0.6; waterTex1 = gl_MultiTexCoord0 + t1 * windFactor; waterTex2 = gl_MultiTexCoord0 + t2 * windFactor; gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0; gl_Position = ftransform(); // logarithmic depth flogz = 1.0 + gl_Position.w; // here start computations for the haze layer float yprime; float lightArg; float intensity; float vertex_alt; float scattering; // we need several geometrical quantities // first current altitude of eye position in model space vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0); // 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 = 0.5 + 0.5 * ground_scattering + 0.5* (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 lightHorizon = normalize(vec3(lightdir.x,lightdir.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; specular_light.b = light_func(lightArg, 1.330e-05, 0.264, 3.827, 1.08e-05, 1.0); specular_light.g = light_func(lightArg, 3.931e-06, 0.264, 3.827, 7.93e-06, 1.0); specular_light.r = light_func(lightArg, 8.305e-06, 0.161, 3.827, 3.04e-05, 1.0); specular_light = max(specular_light * scattering, vec3 (0.05, 0.05, 0.05)); intensity = length(specular_light.rgb); specular_light.rgb = intensity * normalize(mix(specular_light.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.6,ground_scattering) )); specular_light.rgb = intensity * normalize(mix(specular_light.rgb, shadedFogColor, 1.0 -smoothstep(0.5, 0.7,earthShade))); // directional scattering for low sun if (lightArg < 10.0) {mie_angle = (0.5 * dot(normalize(relPos), lightdir) ) + 0.5;} else {mie_angle = 1.0;} // 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) {specular_light = vec3 (1.0, 1.0, 1.0);} else { lightArg = (terminator/100000.0 - 10.0)/20.0; specular_light.b = 0.78 + lightArg * 0.21; specular_light.g = 0.907 + lightArg * 0.091; specular_light.r = 0.904 + lightArg * 0.092; } specular_light = specular_light * scattering; yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude); } gl_FrontColor.rgb = specular_light; gl_BackColor.rgb = gl_FrontColor.rgb; }