scattering: optimize lightDepth along thw view ray

pioneerspacesim · Sep 6, 2023 · bb3519a · bb3519a
1 parent 42be989
commit bb3519a
Showing 1 changed file with 10 additions and 2 deletions.
diff --git a/data/shaders/opengl/geosphere_sky.frag b/data/shaders/opengl/geosphere_sky.frag
@@ -159,12 +159,20 @@ vec3 computeIncidentLight(const in vec3 sunDirection, in vec3 orig, const in vec
 	getCoefficients(kR, bR, cR, earthRadius, atmosphereHeight, Hr);
 	getCoefficients(kM, bM, cM, earthRadius, atmosphereHeight, Hm);
 
+	float h, t;
+	findClosestHeight(h, t, orig, dir, center);
+	h -= earthRadius;
+
+	opticalDepthR = predictDensityOut(atmosphereHeight, h, kR, bR);
+	opticalDepthM = predictDensityOut(atmosphereHeight, h, kM, bM);
+
+	opticalDepthR *= predictDensityIn(earthRadius, atmosphereHeight, h, cR, t);
+	opticalDepthM *= predictDensityIn(earthRadius, atmosphereHeight, h, cM, t);
+
 	for (int i = 0; i < numSamples; ++i) {
 		vec3 samplePosition = orig + vec3(tCurrent + segmentLength * 0.5f) * dir;
 		float hr, hm;
 		scatter(hr, hm, samplePosition, center);
-		opticalDepthR += exp(hr) * segmentLength;
-		opticalDepthM += exp(hm) * segmentLength;
 
 		// light optical depth
 		{