// -*-C++-*- #version 120 varying float fogFactor; varying vec3 hazeColor; uniform float range; // From /sim/rendering/clouds3d-vis-range uniform float scattering; uniform float terminator; uniform float altitude; attribute vec3 usrAttr1; attribute vec3 usrAttr2; float shade_factor = usrAttr1.g; float cloud_height = usrAttr1.b; float bottom_factor = usrAttr2.r; float middle_factor = usrAttr2.g; float top_factor = usrAttr2.b; const float EarthRadius = 5800000.0; // light_func is a generalized logistic function fit to the light intensity as a function // of scaled terminator position obtained from Flightgear core 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 > 30.0) {return e;} if (x < -15.0) {return 0.0;} return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d)); } void main(void) { float intensity; gl_TexCoord[0] = gl_MultiTexCoord0; vec4 ep = gl_ModelViewMatrixInverse * vec4(0.0,0.0,0.0,1.0); vec4 l = gl_ModelViewMatrixInverse * vec4(0.0,0.0,1.0,1.0); vec3 u = normalize(ep.xyz - l.xyz); // Find a rotation matrix that rotates 1,0,0 into u. u, r and w are // the columns of that matrix. vec3 absu = abs(u); vec3 r = normalize(vec3(-u.y, u.x, 0.0)); vec3 w = cross(u, r); // Do the matrix multiplication by [ u r w pos]. Assume no // scaling in the homogeneous component of pos. gl_Position = vec4(0.0, 0.0, 0.0, 1.0); gl_Position.xyz = gl_Vertex.x * u; gl_Position.xyz += gl_Vertex.y * r; gl_Position.xyz += gl_Vertex.z * w; // Apply Z scaling to allow sprites to be squashed in the z-axis gl_Position.z = gl_Position.z * gl_Color.w; // Now shift the sprite to the correct position in the cloud. gl_Position.xyz += gl_Color.xyz; // Determine a lighting normal based on the vertex position from the // center of the cloud, so that sprite on the opposite side of the cloud to the sun are darker. float n = dot(normalize(-gl_LightSource[0].position.xyz), normalize(vec3(gl_ModelViewMatrix * vec4(- gl_Position.x, - gl_Position.y, - gl_Position.z, 0.0)))); // Determine the position - used for fog and shading calculations vec3 ecPosition = vec3(gl_ModelViewMatrix * gl_Position); float fogCoord = abs(ecPosition.z); // Determine the shading of the vertex. We shade it based on it's position // in the cloud relative to the sun, and it's vertical position in the cloud. float shade = mix(shade_factor, top_factor, smoothstep(-0.3, 0.3, n)); //if (n < 0) { // shade = mix(top_factor, shade_factor, abs(n)); //} if (gl_Position.z < 0.5 * cloud_height) { shade = min(shade, mix(bottom_factor, middle_factor, gl_Position.z * 2.0 / cloud_height)); } else { shade = min(shade, mix(middle_factor, top_factor, gl_Position.z * 2.0 / cloud_height - 1.0)); } //float h = gl_Position.z / cloud_height; //if (h < 0.5) { // shade = min(shade, mix(bottom_factor, middle_factor, smoothstep(0.0, 0.5, h))); //} else { // shade = min(shade, mix(middle_factor, top_factor, smoothstep(2.0 * (h - 0.5))); // } // Final position of the sprite vec3 relVector = gl_Position.xyz - ep.xyz; gl_Position = gl_ModelViewProjectionMatrix * gl_Position; // Light at the final position // first obtain normal 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, corrected for altitude // the altitude correction is clamped to reasonable values, sometimes altitude isn't parsed correctly, leading // to overbright or overdark clouds // float vertex_alt = clamp(altitude * 0.30480 + relVector.z,1000.0,10000.0); float vertex_alt = clamp(altitude + relVector.z, 300.0, 10000.0); float yprime = -dot(relVector, lightHorizon); float yprime_alt = yprime -sqrt(2.0 * EarthRadius * vertex_alt); // compute the light at the position vec4 light_diffuse; float lightArg = (terminator-yprime_alt)/100000.0; light_diffuse.b = light_func(lightArg, 1.330e-05, 0.264, 2.227, 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; intensity = length(light_diffuse); light_diffuse = intensity * normalize(mix(light_diffuse, 2.0*vec4 (0.55, 0.6, 0.8, 1.0), (1.0 - smoothstep(0.3,0.8, scattering)))); //gl_FrontColor = gl_LightSource[0].diffuse * shade + gl_FrontLightModelProduct.sceneColor; gl_FrontColor = light_diffuse * shade + gl_FrontLightModelProduct.sceneColor; // As we get within 100m of the sprite, it is faded out. Equally at large distances it also fades out. gl_FrontColor.a = min(smoothstep(10.0, 100.0, fogCoord), 1.0 - smoothstep(range*0.9, range, fogCoord)); //gl_BackColor = gl_FrontColor; // Fog doesn't affect clouds as much as other objects. float fadeScale = 0.05 + 0.2 * log(fogCoord/1000.0); if (fadeScale < 0.05) fadeScale = 0.05; fogFactor = exp( -gl_Fog.density * fogCoord * fadeScale); // Fog doesn't affect clouds as much as other objects. //fogFactor = exp( -gl_Fog.density * fogCoord * 0.5); //fogFactor = clamp(fogFactor, 0.0, 1.0); // haze of ground haze shader is slightly bluish //hazeColor = vec3 (gl_LightSource[0].diffuse.x, gl_LightSource[0].diffuse.y, gl_LightSource[0].diffuse.z); hazeColor = light_diffuse.xyz; hazeColor.x = hazeColor.x * 0.83; hazeColor.y = hazeColor.y * 0.9; hazeColor = hazeColor * scattering; // in sunset or sunrise conditions, do extra shading of clouds // two times terminator width governs how quickly light fades into shadow float terminator_width = 200000.0; float earthShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt) + 0.1; // change haze color to blue hue for strong fogging intensity = length(hazeColor); hazeColor = intensity * normalize(mix(hazeColor, 2.0* vec3 (0.55, 0.6, 0.8), (1.0 - smoothstep(0.3,0.8,scattering)))); hazeColor = hazeColor * earthShade; gl_FrontColor.xyz = gl_FrontColor.xyz * earthShade; gl_BackColor = gl_FrontColor; }