61 lines
1.9 KiB
Text
61 lines
1.9 KiB
Text
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#version 330 core
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uniform sampler2D transmittance_tex;
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uniform vec3 fg_CameraPositionCart;
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uniform vec3 fg_SunDirectionWorld;
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const int AERIAL_PERSPECTIVE_ENVMAP_STEPS = 4;
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// atmos.glsl
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float get_earth_radius();
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float get_ray_end(vec3 ray_origin, vec3 ray_dir, float t_max);
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vec4 compute_inscattering(in vec3 ray_origin,
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in vec3 ray_dir,
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in float t_max,
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in vec3 sun_dir,
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in int steps,
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in sampler2D transmittance_lut,
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out vec4 transmittance);
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// atmos_spectral.glsl
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vec4 get_sun_spectral_irradiance();
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vec3 linear_srgb_from_spectral_samples(vec4 L);
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vec4 get_aerial_perspective(vec3 pos)
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{
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vec3 ray_origin = fg_CameraPositionCart;
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vec3 ray_end = pos;
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// Make sure both ray ends are above the ground.
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// We also apply a small bias to the ray end to prevent both points from
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// being at the exact same place due to floating point precision.
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float radius = get_earth_radius();
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ray_origin += max(0.0, radius - length(ray_origin));
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ray_end += max(0.0, radius - length(ray_end)) + 1.0;
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vec3 ray_dir = ray_end - ray_origin;
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float t_d = length(ray_dir);
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ray_dir /= t_d;
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float t_max = get_ray_end(ray_origin, ray_dir, t_d);
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vec4 transmittance;
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vec4 L = compute_inscattering(ray_origin,
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ray_dir,
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t_max,
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fg_SunDirectionWorld,
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AERIAL_PERSPECTIVE_ENVMAP_STEPS,
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transmittance_tex,
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transmittance);
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vec4 ap;
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ap.rgb = linear_srgb_from_spectral_samples(L * get_sun_spectral_irradiance());
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ap.a = dot(transmittance, vec4(0.25));
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return ap;
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}
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vec3 mix_aerial_perspective(vec3 color, vec4 ap)
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{
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return color * ap.a + ap.rgb;
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}
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