Document the deprecation of hardcoded cave liquids (#8692)

src/mapgen/cavegen.cpp

@@ -29,6 +29,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "mg_biome.h"
 #include "cavegen.h"
 
+// TODO Remove this. Cave liquids are now defined and located using biome definitions
 static NoiseParams nparams_caveliquids(0, 1, v3f(150.0, 150.0, 150.0), 776, 3, 0.6, 2.0);
 
 
@@ -526,7 +527,9 @@ void CavesRandomWalk::carveRoute(v3f vec, float f, bool randomize_xz)
 		if (use_biome_liquid) {
 			liquidnode = c_biome_liquid;
 		} else {
-			// If cave liquid not defined by biome, fallback to old hardcoded behaviour
+			// TODO remove this. Cave liquids are now defined and located using biome
+			// definitions.
+			// If cave liquid not defined by biome, fallback to old hardcoded behaviour.
 			float nval = NoisePerlin3D(np_caveliquids, startp.X,
 				startp.Y, startp.Z, seed);
 			liquidnode = (nval < 0.40f && node_max.Y < lava_depth) ?

src/mapgen/cavegen.h

@@ -119,6 +119,8 @@ public:
 	// configurable parameters
 	s32 seed;
 	int water_level;
+	// TODO 'lava_depth' and 'np_caveliquids' are deprecated and should be removed.
+	// Cave liquids are now defined and located using biome definitions.
 	int lava_depth;
 	NoiseParams *np_caveliquids;
 

src/mapgen/mapgen.h

@@ -278,5 +278,7 @@ protected:
 	float cavern_limit;
 	float cavern_taper;
 	float cavern_threshold;
+	// TODO 'lava_depth' is deprecated and should be removed. Cave liquids are
+	// now defined and located using biome definitions.
 	int lava_depth;
 };