// -*-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 vec3 relPos; varying float yprime_alt; varying float autumn_flag; uniform int colorMode; uniform int wind_effects; uniform int forest_effects; uniform int num_deciduous_trees; 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 snow_level; uniform float season; uniform float WindN; uniform float WindE; uniform float osg_SimulationTime; uniform int cloud_shadow_flag; float earthShade; float mie_angle; float shadow_func (in float x, in float y, in float noise, in float dist); float VoronoiNoise2D(in vec2 coord, in float wavelength, in float xrand, in float yrand); // 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 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_ambient; vec3 shadedFogColor = vec3(0.55, 0.67, 0.88); float yprime; float lightArg; float intensity; float vertex_alt; float scattering; // this code is copied from tree.vert float numVarieties = gl_Normal.z; float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties; // determine whether the tree changes color in autumn if (texFract < (float) num_deciduous_trees/numVarieties) {autumn_flag = 0.5 + fract(gl_Color.x);} else {autumn_flag = 0.0;} texFract += floor(gl_MultiTexCoord0.x) / numVarieties; // Determine the rotation for the tree. The Fog Coordinate provides rotation information // to rotate one of the quands by 90 degrees. We then apply an additional position seed // so that trees aren't all oriented N/S float sr = sin(gl_FogCoord + gl_Color.x); float cr = cos(gl_FogCoord + gl_Color.x); gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0); // Determine the y texture coordinate based on whether it's summer, winter, snowy. gl_TexCoord[0].y = gl_TexCoord[0].y + 0.25 * step(snow_level, gl_Color.z) + 0.5 * season; // scaling vec3 position = gl_Vertex.xyz * gl_Normal.xxy; // Rotation of the generic quad to specific one for the tree. position.xy = vec2(dot(position.xy, vec2(cr, sr)), dot(position.xy, vec2(-sr, cr))); // Shear by wind. Note that this only applies to the top vertices if (wind_effects > 0) { position.x = position.x + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindN; position.y = position.y + position.z * (sin(osg_SimulationTime * 1.8 + (gl_Color.x + gl_Color.y + gl_Color.z) * 0.01) + 1.0) * 0.0025 * WindE; } // Scale by random domains float voronoi; if (forest_effects > 0) { voronoi = 0.5 + 1.0 * VoronoiNoise2D(gl_Color.xy, 200.0, 1.5, 1.5); position.xyz = position.xyz * voronoi; } // Move to correct location (stored in gl_Color) position = position + gl_Color.xyz; gl_Position = gl_ModelViewProjectionMatrix * vec4(position,1.0); vec3 ecPosition = vec3(gl_ModelViewMatrix * vec4(position, 1.0)); //normal = normalize(-ecPosition); //float n = dot(normalize(gl_LightSource[0].position.xyz), normalize(-ecPosition)); //vec4 diffuse_color = gl_FrontMaterial.diffuse * max(0.1, n); //diffuse_color.a = 1.0; vec4 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 = position - 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(position.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_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 * (0.4 + 0.6 * smoothstep(0.2, 0.5, earthShade)); intensity = length(light_ambient.rgb); light_ambient.rgb = intensity * normalize(mix(light_ambient.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,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 { earthShade = 1.0; mie_angle = 1.0; if (terminator > 3000000.0) {light_ambient = vec4 (0.33, 0.4, 0.5, 1.0); } else { lightArg = (terminator/100000.0 - 10.0)/20.0; 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; } yprime_alt = -sqrt(2.0 * EarthRadius * hazeLayerAltitude); } light_ambient.rgb = light_ambient.rgb * (1.0 + smoothstep(1000000.0, 3000000.0,terminator)); // tree shader lighting if (cloud_shadow_flag == 1) {light_ambient.rgb = light_ambient.rgb * (0.5 + 0.5 * shadow_func(relPos.x, relPos.y, 1.0, dist));} //vec4 ambientColor = gl_FrontLightModelProduct.sceneColor + //gl_FrontColor = ambientColor; gl_FrontColor = light_ambient * gl_FrontMaterial.ambient; gl_FrontColor.a = mie_angle; gl_BackColor.a = mie_angle; }