Add cave zone and decrease the fog effect there

mods/sf_sky/init.lua

@@ -118,7 +118,35 @@ register_sky("fog", {
         },
         day_night_ratio = 0.5,
 })
-
+register_sky("fog_underground", {
+        sky = {
+                sky_color = {
+                        night_horizon = "#909090",
+                        night_sky = "#808080",
+                        dawn_horizon = "#909090",
+                        dawn_sky = "#808080",
+                        day_horizon = "#909090",
+                        day_sky = "#808080",
+                        indoors = "#000000",
+                },
+                fog = {
+                        fog_distance = 70,
+                        fog_start = 0.5,
+                },
+                clouds = false,
+        },
+        sun = {
+                visible = false,
+                sunrise_visible = false,
+        },
+        moon = {
+                visible = false,
+        },
+        stars = {
+                visible = false,
+        },
+        day_night_ratio = 0.5,
+})
 
 register_sky("night", {
 	sky = {

mods/sf_zones/init.lua

@@ -352,8 +352,16 @@ sf_zones.register_zone("snow_mountain_shrine", {
 	}},
 	music = "crystal",
 })
-sf_zones.register_zone("fog_chasm_shrine", {
+sf_zones.register_zone("cave", {
 	parent = "fog_chasm",
+	areas = {{
+		pos_min = vector.new(281, 15, 16),
+		pos_max = vector.new(350, 22, 54),
+	}},
+	sky = "fog_underground",
+})
+sf_zones.register_zone("fog_chasm_shrine", {
+	parent = "cave",
 	areas = {{
 		pos_min = vector.new(316, 15, 20),
 		pos_max = vector.new(348, 31, 48),