From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 8 Oct 2021 06:16:41 +0000 (+0300)
Subject: Add a shadowing term from the planet to atmospheric transmittance
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=a5f76ec38d682108e8c655a25b32b88e19bd8783;p=libs%2Fgl.git

Add a shadowing term from the planet to atmospheric transmittance

This makes the sky properly dark if the sun is below the horizon.
---

diff --git a/builtin_data/_sky.glsl b/builtin_data/_sky.glsl
index 3493b5a4..81f9d163 100644
--- a/builtin_data/_sky.glsl
+++ b/builtin_data/_sky.glsl
@@ -123,11 +123,15 @@ OpticalPathInfo raymarch_path(float start_height, vec3 look_dir)
 
 		AtmosphericEvents ev = calculate_events(height);
 		vec3 transmittance = exp(-path_extinction);
-		vec3 in_transmittance = texture(transmittance_lookup, vec2(sqrt(height/atmosphere_thickness), light_z)).rgb;
-		vec3 in_luminance = (ev.rayleigh_scatter*p_rayleigh+ev.mie_scatter*p_mie)*step_size;
-		if(i==n_steps && ground_t>0.0)
-			in_luminance += ground_albedo*light_z/PI;
-		path_luminance += transmittance*in_transmittance*in_luminance;
+		float in_ground_t = ray_sphere_intersect(pos+light_dir, light_dir, planet_center, planet_radius);
+		if(in_ground_t<0.0)
+		{
+			vec3 in_transmittance = texture(transmittance_lookup, vec2(sqrt(height/atmosphere_thickness), light_z)).rgb;
+			vec3 in_luminance = (ev.rayleigh_scatter*p_rayleigh+ev.mie_scatter*p_mie)*step_size;
+			if(i==n_steps && ground_t>0.0 && light_z>0.0)
+				in_luminance += ground_albedo*light_z/PI;
+			path_luminance += transmittance*in_transmittance*in_luminance;
+		}
 
 		path_extinction += total_extinction(ev)*step_size;
 		pos += look_dir*step_size;