FindSpawnPos: Let mapgens decide what spawn altitude is suitable

To avoid spawn search failing in new specialised mapgens
Increase spawn search range to 4000 nodes
Add getSpawnLevelAtPoint() functions to EmergeManager, class Mapgen
and all mapgens
Remove getGroundLevelAtPoint() functions from all mapgens except mgv6
(possibly to be re-added later in the correct form to return actual
ground level)
Make mgvalleys flag names consistent with other mapgens
Remove now unused 'vertical spawn range' setting

1 files changed, 14 insertions, 7 deletions

diff --git a/src/mapgen_flat.cpp b/src/mapgen_flat.cpp
index 3b7178dd7..0d071411d 100644
--- a/src/mapgen_flat.cpp
+++ b/src/mapgen_flat.cpp
@@ -192,18 +192,25 @@ void MapgenFlatParams::writeParams(Settings *settings) const
 /////////////////////////////////////////////////////////////////
 
 
-int MapgenFlat::getGroundLevelAtPoint(v2s16 p)
+int MapgenFlat::getSpawnLevelAtPoint(v2s16 p)
 {
+	s16 level_at_point = ground_level;
 	float n_terrain = NoisePerlin2D(&noise_terrain->np, p.X, p.Y, seed);
+
 	if ((spflags & MGFLAT_LAKES) && n_terrain < lake_threshold) {
-		s16 depress = (lake_threshold - n_terrain) * lake_steepness;
-		return ground_level - depress;
+		level_at_point = ground_level -
+			(lake_threshold - n_terrain) * lake_steepness;
 	} else if ((spflags & MGFLAT_HILLS) && n_terrain > hill_threshold) {
-		s16 rise = (n_terrain - hill_threshold) * hill_steepness;
-		return ground_level + rise;
-	} else {
-		return ground_level;
+		level_at_point = ground_level +
+			(n_terrain - hill_threshold) * hill_steepness;
 	}
+
+	if (ground_level < water_level)  // Ocean world, allow spawn in water
+		return MYMAX(level_at_point, water_level);
+	else if (level_at_point > water_level)
+		return level_at_point;  // Spawn on land
+	else
+		return MAX_MAP_GENERATION_LIMIT;  // Unsuitable spawn point
 }