Lessen the sky color glitch when quickly turning to look up after looking at...

Lessen the sky color glitch when quickly turning to look up after looking at ground that contains caves

src/sky.cpp

@@ -433,9 +433,14 @@ void Sky::update(float time_of_day, float time_brightness,
 	//video::SColorf cloudcolor_bright_dawn_f(1.0, 0.65, 0.44);
 	video::SColorf cloudcolor_bright_dawn_f(1.0, 0.7, 0.5);
 
+	float cloud_color_change_fraction = 0.95;
 	if(sunlight_seen){
-		//m_brightness = m_brightness * 0.95 + direct_brightness * 0.05;
-		m_brightness = m_brightness * 0.95 + time_brightness * 0.05;
+		if(fabs(time_brightness - m_brightness) < 0.2){
+			m_brightness = m_brightness * 0.95 + time_brightness * 0.05;
+		} else {
+			m_brightness = m_brightness * 0.80 + time_brightness * 0.20;
+			cloud_color_change_fraction = 0.0;
+		}
 	}
 	else{
 		if(direct_brightness < m_brightness)
@@ -493,8 +498,8 @@ void Sky::update(float time_of_day, float time_brightness,
 	} else {
 		cloud_direct_brightness = direct_brightness;
 	}
-	m_cloud_brightness = m_cloud_brightness * 0.95 +
-			cloud_direct_brightness * (1.0 - 0.95);
+	m_cloud_brightness = m_cloud_brightness * cloud_color_change_fraction +
+			cloud_direct_brightness * (1.0 - cloud_color_change_fraction);
 	m_cloudcolor_f = video::SColorf(
 			m_cloudcolor_bright_f.getRed() * m_cloud_brightness,
 			m_cloudcolor_bright_f.getGreen() * m_cloud_brightness,