134 lines
4.8 KiB
GLSL
134 lines
4.8 KiB
GLSL
// -*-C++-*-
|
|
#version 120
|
|
|
|
varying float fogFactor;
|
|
varying vec3 hazeColor;
|
|
|
|
uniform float terminator;
|
|
uniform float altitude;
|
|
uniform float cloud_self_shading;
|
|
uniform float moonlight;
|
|
|
|
const float shade = 1.0;
|
|
const float cloud_height = 1000.0;
|
|
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 0.03;}
|
|
|
|
|
|
return e / pow((1.0 + a * exp(-b * (x-c)) ),(1.0/d));
|
|
}
|
|
|
|
void main(void)
|
|
{
|
|
|
|
vec3 shadedFogColor = vec3 (0.55, 0.67, 0.88);
|
|
vec3 moonLightColor = vec3 (0.095, 0.095, 0.15) * moonlight;
|
|
|
|
gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;
|
|
//gl_TexCoord[0] = gl_MultiTexCoord0 + vec4(textureIndexX, textureIndexY, 0.0, 0.0);
|
|
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);
|
|
|
|
gl_Position = vec4(0.0, 0.0, 0.0, 1.0);
|
|
gl_Position.x = gl_Vertex.x;
|
|
gl_Position.y += gl_Vertex.y;
|
|
gl_Position.z += gl_Vertex.z;
|
|
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(mat3x3(gl_ModelViewMatrix) * (- gl_Position.xyz)));;
|
|
|
|
// Determine the position - used for fog and shading calculations
|
|
vec3 ecPosition = vec3(gl_ModelViewMatrix * gl_Position);
|
|
float fogCoord = abs(ecPosition.z);
|
|
float fract = smoothstep(0.0, cloud_height, gl_Position.z + cloud_height);
|
|
|
|
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
|
|
//float vertex_alt = max(altitude * 0.30480 + relVector.z,100.0);
|
|
float vertex_alt = altitude + relVector.z;
|
|
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 = 1.0;
|
|
|
|
float intensity = length(light_diffuse.rgb);
|
|
light_diffuse.rgb = intensity * normalize(mix(light_diffuse.rgb, shadedFogColor, (1.0 - smoothstep(0.5,0.9, cloud_self_shading ))));
|
|
|
|
// Determine the shading of the sprite based on its vertical position and position relative to the sun.
|
|
n = min(smoothstep(-0.5, 0.0, n), fract);
|
|
// Determine the shading based on a mixture from the backlight to the front
|
|
vec4 backlight = light_diffuse * shade;
|
|
|
|
gl_FrontColor = mix(backlight, light_diffuse, n);
|
|
gl_FrontColor += 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(100.0, 250.0, fogCoord), 1.0 - smoothstep(70000.0, 75000.0, fogCoord));
|
|
|
|
// Fog doesn't affect rain as much as other objects.
|
|
//fogFactor = exp( -gl_Fog.density * fogCoord * 0.4);
|
|
//fogFactor = clamp(fogFactor, 0.0, 1.0);
|
|
|
|
float fadeScale = 0.05 + 0.2 * log(fogCoord/1000.0);
|
|
if (fadeScale < 0.05) fadeScale = 0.05;
|
|
fogFactor = exp( -gl_Fog.density * fogCoord * fadeScale);
|
|
|
|
hazeColor = light_diffuse.rgb;
|
|
hazeColor.r = hazeColor.r * 0.83;
|
|
hazeColor.g = hazeColor.g * 0.9;
|
|
|
|
// 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;
|
|
|
|
// now dim the light
|
|
float earthShade = 0.9 * smoothstep(terminator_width+ terminator, -terminator_width + terminator, yprime_alt) + 0.1;
|
|
|
|
if (earthShade < 0.8)
|
|
{
|
|
intensity = length(light_diffuse.rgb);
|
|
gl_FrontColor.rgb = intensity * normalize(mix(gl_FrontColor.rgb, shadedFogColor, 1.0 -smoothstep(0.1, 0.8,earthShade ) ));
|
|
}
|
|
|
|
hazeColor = hazeColor * earthShade;
|
|
gl_FrontColor.rgb = gl_FrontColor.rgb * earthShade;
|
|
gl_FrontColor.rgb = gl_FrontColor.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade));
|
|
hazeColor.rgb = hazeColor.rgb + moonLightColor * (1.0 - smoothstep(0.4, 0.5, earthShade));
|
|
gl_BackColor = gl_FrontColor;
|
|
|
|
}
|