Biome API: Add decoration flags for underground decorations

Add "all_floors" and "all_ceilings" flags for simple and schematic
decorations. Decorations are placed on all floor and/or ceiling surfaces.
Decorations are placed before dungeon generation so placement in dungeons
is not possible.

Add 'getSurfaces()' function to mapgen.cpp that returns 2 arrays of y
coordinates for all floor and ceiling surfaces in a specified node column.

Move 'getHeight()' checks into DecoSimple and DecoSchematic. Delete
'getHeight()' functions.

1 files changed, 5 insertions, 6 deletions

diff --git a/src/mg_decoration.h b/src/mg_decoration.h
index 9295d1a20..1ca632f25 100644
--- a/src/mg_decoration.h
+++ b/src/mg_decoration.h
@@ -42,6 +42,8 @@ enum DecorationType {
 #define DECO_USE_NOISE       0x08
 #define DECO_FORCE_PLACEMENT 0x10
 #define DECO_LIQUID_SURFACE  0x20
+#define DECO_ALL_FLOORS      0x40
+#define DECO_ALL_CEILINGS    0x80
 
 extern FlagDesc flagdesc_deco[];
 
@@ -56,8 +58,7 @@ public:
 	bool canPlaceDecoration(MMVManip *vm, v3s16 p);
 	size_t placeDeco(Mapgen *mg, u32 blockseed, v3s16 nmin, v3s16 nmax);
 
-	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p) = 0;
-	virtual int getHeight() = 0;
+	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p, bool ceiling) = 0;
 
 	u32 flags = 0;
 	int mapseed = 0;
@@ -78,8 +79,7 @@ public:
 class DecoSimple : public Decoration {
 public:
 	virtual void resolveNodeNames();
-	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p);
-	virtual int getHeight();
+	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p, bool ceiling);
 
 	std::vector<content_t> c_decos;
 	s16 deco_height;
@@ -93,8 +93,7 @@ class DecoSchematic : public Decoration {
 public:
 	DecoSchematic() = default;
 
-	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p);
-	virtual int getHeight();
+	virtual size_t generate(MMVManip *vm, PcgRandom *pr, v3s16 p, bool ceiling);
 
 	Rotation rotation;
 	Schematic *schematic = nullptr;