From b2acf5a623a3bb059bc1f3811ecff13589688b41 Mon Sep 17 00:00:00 2001
From: Scott Giese <scttgs0@gmail.com>
Date: Thu, 24 Dec 2020 15:39:39 -0600
Subject: [PATCH] fix: sky and cockpit to turn black

Metar sky condition without base layer height (e.g. FEW///) is the cause of this issue.
Randomize the base layer height when the actual height is unknown.
---
 simgear/environment/metar.cxx | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/simgear/environment/metar.cxx b/simgear/environment/metar.cxx
index 3a70842e..789f7a0d 100644
--- a/simgear/environment/metar.cxx
+++ b/simgear/environment/metar.cxx
@@ -46,6 +46,7 @@
 #include <sstream>
 
 #include <simgear/debug/logstream.hxx>
+#include <simgear/math/sg_random.h>
 #include <simgear/structure/exception.hxx>
 
 #include "metar.hxx"
@@ -1068,9 +1069,12 @@ bool SGMetar::scanSkyCondition()
 		return false;
 	m += i;
 
-	if (!strncmp(m, "///", 3))	// vis not measurable (e.g. because of heavy snowing)
+	if (!strncmp(m, "///", 3))	{ // vis not measurable (e.g. because of heavy snowing)
 		m += 3, i = -1;
-	else if (scanBoundary(&m)) {
+		sg_srandom_time();
+		// randomize the base height to avoid the black sky issue
+		i = 50 + static_cast<int>(sg_random() * 250.0);		// range [5,000, 30,000]
+	} else if (scanBoundary(&m)) {
 		_m = m;
 		return true;				// ignore single OVC/BKN/...
 	} else if (!scanNumber(&m, &i, 3))