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/**
* @file WLCloudsF.glsl
*
* $LicenseInfo:firstyear=2005&license=viewerlgpl$
* $/LicenseInfo$
*/
#version 120
/////////////////////////////////////////////////////////////////////////
// The fragment shader for the sky
/////////////////////////////////////////////////////////////////////////
varying vec4 vary_CloudColorSun;
varying vec4 vary_CloudColorAmbient;
varying float vary_CloudDensity;
uniform sampler2D cloud_noise_texture;
uniform vec4 cloud_pos_density1;
uniform vec4 cloud_pos_density2;
uniform vec4 gamma;
/// Soft clips the light with a gamma correction
vec3 scaleSoftClip(vec3 light) {
//soft clip effect:
light = 1. - clamp(light, vec3(0.), vec3(1.));
light = 1. - pow(light, gamma.xxx);
return light;
}
void main()
{
// Set variables
vec2 uv1 = gl_TexCoord[0].xy;
vec2 uv2 = gl_TexCoord[1].xy;
vec4 cloudColorSun = vary_CloudColorSun;
vec4 cloudColorAmbient = vary_CloudColorAmbient;
float cloudDensity = vary_CloudDensity;
vec2 uv3 = gl_TexCoord[2].xy;
vec2 uv4 = gl_TexCoord[3].xy;
// Offset texture coords
uv1 += cloud_pos_density1.xy; //large texture, visible density
uv2 += cloud_pos_density1.xy; //large texture, self shadow
uv3 += cloud_pos_density2.xy; //small texture, visible density
uv4 += cloud_pos_density2.xy; //small texture, self shadow
// Compute alpha1, the main cloud opacity
float alpha1 = (texture2D(cloud_noise_texture, uv1).x - 0.5) + (texture2D(cloud_noise_texture, uv3).x - 0.5) * cloud_pos_density2.z;
alpha1 = min(max(alpha1 + cloudDensity, 0.) * 10. * cloud_pos_density1.z, 1.);
// And smooth
alpha1 = 1. - alpha1 * alpha1;
alpha1 = 1. - alpha1 * alpha1;
// Compute alpha2, for self shadowing effect
// (1 - alpha2) will later be used as percentage of incoming sunlight
float alpha2 = (texture2D(cloud_noise_texture, uv2).x - 0.5);
alpha2 = min(max(alpha2 + cloudDensity, 0.) * 2.5 * cloud_pos_density1.z, 1.);
// And smooth
alpha2 = 1. - alpha2;
alpha2 = 1. - alpha2 * alpha2;
// Combine
vec4 color;
color = (cloudColorSun*(1.-alpha2) + cloudColorAmbient);
color *= 2.;
/// Gamma correct for WL (soft clip effect).
gl_FragColor.rgb = scaleSoftClip(color.rgb);
gl_FragColor.a = alpha1;
}
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