// -*-C++-*- // 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. // Haze part added by Thorsten Renk, Oct. 2011 #define MODE_OFF 0 #define MODE_DIFFUSE 1 #define MODE_AMBIENT_AND_DIFFUSE 2 // The constant 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 earthShade; //varying float yprime; //varying float vertex_alt; varying float yprime_alt; varying float mie_angle; uniform int colorMode; uniform float hazeLayerAltitude; uniform float terminator; uniform float terrain_alt; uniform float avisibility; uniform float visibility; uniform float overcast; //uniform float scattering; uniform float ground_scattering; // 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)); } void main() { vec4 light_diffuse; vec4 light_ambient; //float yprime_alt; float yprime; float lightArg; float intensity; float vertex_alt; float scattering; // this code is copied from default.vert //vec4 ecPosition = gl_ModelViewMatrix * gl_Vertex; gl_Position = ftransform(); 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; } // here start computations for the haze layer // 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 = 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 = 0.0; light_diffuse = light_diffuse * scattering; light_ambient.b = light_func(lightArg, 0.000506, 0.131, -3.315, 0.000457, 0.5); light_ambient.g = light_func(lightArg, 2.264e-05, 0.134, 0.967, 3.66e-05, 0.4); light_ambient.r = light_func(lightArg, 0.236, 0.253, 1.073, 0.572, 0.33); light_ambient.a = 0.0; // 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.xyz = intensity * normalize(mix(light_ambient.xyz, vec3 (0.45, 0.6, 0.8), 1.0 -smoothstep(0.1, 0.8,earthShade) )); intensity = length(light_diffuse.xyz); light_diffuse.xyz = intensity * normalize(mix(light_diffuse.xyz, vec3 (0.45, 0.6, 0.8), 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 = 0.0; light_ambient.b = 0.41 + lightArg * 0.08; light_ambient.g = 0.333 + lightArg * 0.06; light_ambient.r = 0.316 + lightArg * 0.016; light_ambient.a = 0.0; } light_diffuse = light_diffuse * scattering; yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude); } // 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; }