From 9ffb8a3d524ff9a866f9982b4f06acaf4545ab77 Mon Sep 17 00:00:00 2001 From: Thorsten Renk Date: Fri, 1 Mar 2013 09:11:10 +0200 Subject: [PATCH] 'The Flag' for Atmospheric Light Scattering --- Effects/flutter.eff | 219 ++++++++++++++++++++++ Shaders/flutter-lightfield.vert | 312 ++++++++++++++++++++++++++++++++ 2 files changed, 531 insertions(+) create mode 100644 Shaders/flutter-lightfield.vert diff --git a/Effects/flutter.eff b/Effects/flutter.eff index 47c46b65b..a5d9ca51d 100644 --- a/Effects/flutter.eff +++ b/Effects/flutter.eff @@ -48,6 +48,225 @@ + + + + + /sim/rendering/shaders/skydome + + + 2.0 + + + + GL_ARB_shader_objects + GL_ARB_shading_language_100 + GL_ARB_vertex_shader + GL_ARB_fragment_shader + + + + + + true + + + material/active + + + material/ambient + + + material/diffuse + + + material/specular + + + material/emissive + + + material/shininess + + + material/color-mode + + + + + blend/active + + + blend/source + + + blend/destination + + + + shade-model + + + cull-face + + + rendering-hint + + + + 0 + + + texture[0]/type + + + texture[0]/image + + + texture[0]/filter + + + texture[0]/wrap-s + + + texture[0]/wrap-t + + + + + 1 + noise + + + vertex-program-two-side + + + + Shaders/flutter-lightfield.vert + Shaders/terrain-haze.frag + + + + colorMode + int + + material/color-mode-uniform + + + + + Offset + float + + offset + + + + AmpFactor + float + + amplitude-factor + + + + Noise + sampler-3d + 1 + + + WindE + float + + windE + + + + WindN + float + + windN + + + + spd + float + + speed-kt + + + + hdg + float + + heading-deg + + + + + + visibility + float + + visibility + + + + avisibility + float + + avisibility + + + + hazeLayerAltitude + float + + lthickness + + + + scattering + float + + scattering + + + + terminator + float + + terminator + + + + fogType + int + + fogtype + + + + + + + + diff --git a/Shaders/flutter-lightfield.vert b/Shaders/flutter-lightfield.vert new file mode 100644 index 000000000..96d8ef280 --- /dev/null +++ b/Shaders/flutter-lightfield.vert @@ -0,0 +1,312 @@ +// -*-C++-*- +// © Vivian Meazza - 2011 +// adapted to Atmospheric Light Scattering by Thorsten Renk 2013 + +// Shader that uses OpenGL state values to do per-pixel lighting +// +// The only light used is gl_LightSource[0], which is assumed to be +// directional. +// +// Diffuse colors come from the gl_Color, ambient from the material. This is +// equivalent to osg::Material::DIFFUSE. + +#version 120 +#define fps2kts 0.5925 + +#define MODE_OFF 0 +#define MODE_DIFFUSE 1 +#define MODE_AMBIENT_AND_DIFFUSE 2 + +// The ambient term of the lighting equation that doesn't depend on +// the surface normal is passed in gl_{Front,Back}Color. The alpha +// component is set to 1 for front, 0 for back in order to work around +// bugs with gl_FrontFacing in the fragment shader. +varying vec4 diffuse_term; +varying vec3 normal; +varying vec3 relPos; + +varying float yprime_alt; +varying float mie_angle; + + +uniform int colorMode; +uniform float osg_SimulationTime; +uniform float Offset, AmpFactor, WindE, WindN, spd, hdg; +uniform sampler3D Noise; +uniform float hazeLayerAltitude; +uniform float terminator; +uniform float terrain_alt; +uniform float avisibility; +uniform float visibility; +uniform float overcast; +uniform float ground_scattering; +uniform float moonlight; + +// 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; + +float earthShade; + +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)); +} + +float normalize_range(float _val) + { + if (_val > 180.0) + return _val - 360.0; + else + return _val; + } + +void relWind(out float rel_wind_speed_kts, out float rel_wind_from_rad) + { + //calculate 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(pow(abs(rel_wind_speed_from_east_kts), 2.0) + + pow(abs(rel_wind_speed_from_north_kts), 2.0)); + + //calculate the relative wind direction + float rel_wind_from_deg = degrees(atan(rel_wind_speed_from_east_kts, rel_wind_speed_from_north_kts)); + //rel_wind_from_rad = atan(rel_wind_speed_from_east_kts, rel_wind_speed_from_north_kts); + float rel_wind = rel_wind_from_deg - hdg; + rel_wind = normalize_range(rel_wind); + rel_wind_from_rad = radians(rel_wind); + } + +void rotationmatrix(in float angle, out mat4 rotmat) + { + rotmat = mat4( cos( angle ), -sin( angle ), 0.0, 0.0, + sin( angle ), cos( angle ), 0.0, 0.0, + 0.0 , 0.0 , 1.0, 0.0, + 0.0 , 0.0 , 0.0, 1.0 ); + } + +void main() + { + vec4 light_diffuse; + vec4 light_ambient; + vec3 shadedFogColor = vec3(0.65, 0.67, 0.78); + vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight; + + + float yprime; + float lightArg; + float intensity; + float vertex_alt; + float scattering; + + + + mat4 RotationMatrix; + + float relWindspd=0.0; + float relWinddir=0.0; + + // compute relative wind speed and direction + relWind (relWindspd, relWinddir); + + // map noise vector + vec4 noisevec = texture3D(Noise, gl_Vertex.xyz); + + //waving effect + float tsec = osg_SimulationTime; + vec4 pos = gl_Vertex; + vec4 oldpos = gl_Vertex; + + float freq = (10.0 * relWindspd) + 10.0; + pos.y = sin((pos.x * 5.0 + tsec * freq )/5.0) * 0.5 ; + pos.y += sin((pos.z * 5.0 + tsec * freq/2.0)/5.0) * 0.125 ; + + pos.y *= pow(pos.x - Offset, 2.0) * AmpFactor; + + //rotate the flag to align with relative wind + rotationmatrix(-relWinddir, RotationMatrix); + pos *= RotationMatrix; + gl_Position = gl_ModelViewProjectionMatrix * pos; + + //do the colour and fog + vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex; + + + gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0; + normal = gl_NormalMatrix * gl_Normal; + vec4 ambient_color, diffuse_color; + + if (colorMode == MODE_DIFFUSE) { + diffuse_color = gl_Color; + ambient_color = gl_FrontMaterial.ambient; + } else if (colorMode == MODE_AMBIENT_AND_DIFFUSE) { + diffuse_color = gl_Color; + ambient_color = gl_Color; + } else { + diffuse_color = gl_FrontMaterial.diffuse; + ambient_color = gl_FrontMaterial.ambient; + } + + + // 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 = 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.xyz); + + light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,earthShade) )); + light_ambient.rgb = light_ambient.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade)); + + intensity = length(light_diffuse.xyz); + light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 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); +} + + + + + + diffuse_term = diffuse_color * light_diffuse; + vec4 ambient_term = ambient_color * 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 = ambient_term.rgb; gl_FrontColor.a = 0.0; + gl_BackColor.rgb = ambient_term.rgb; gl_FrontColor.a = 1.0; +// fogCoord = abs(ecPosition.z / ecPosition.w); + + //fog_Func(fogType); + + }