Add Ore generation flags, implement ore absolute height

doc/lua_api.txt

@@ -394,6 +394,13 @@ All default ores are of the uniformly-distributed scatter type.
     Places ore if there are no more than clust_scarcity number of specified nodes within a Von Neumann
     neighborhood of clust_size radius.
 
+Ore attributes
+-------------------
+Currently supported flags:  absheight
+ - absheight
+    Also produce this same ore between the height range of -height_max and -height_min.
+    Useful for having ore in sky realms without having to duplicate ore entries.
+
 Representations of simple things
 --------------------------------
 Position/vector:
@@ -1723,6 +1730,8 @@ Ore definition (register_ore)
     ^ In this example, there is a 3x3x3 cluster where 8 out of the 27 nodes are coal ore
     height_min = -31000,
     height_max = 64,
+    flags = "",
+    ^ Attributes for this ore generation
     noise_threshhold = 0.5,
     ^ If noise is above this threshhold, ore is placed.  Not needed for a uniform distribution
     noise_params = {offset=0, scale=1, spread={x=100, y=100, z=100}, seed=23, octaves=3, persist=0.70}

src/mapgen.cpp

@@ -42,7 +42,14 @@ FlagDesc flagdesc_mapgen[] = {
 	{"v6_jungles",     MGV6_JUNGLES},
 	{"v6_biome_blend", MGV6_BIOME_BLEND},
 	{"flat",           MG_FLAT},
-	{NULL,			   0}
+	{NULL,             0}
+};
+
+FlagDesc flagdesc_ore[] = {
+	{"absheight",            OREFLAG_ABSHEIGHT},
+	{"scatter_noisedensity", OREFLAG_DENSITY},
+	{"claylike_nodeisnt",    OREFLAG_NODEISNT},
+	{NULL,                   0}
 };
 
 
@@ -87,17 +94,28 @@ void Ore::resolveNodeNames(INodeDefManager *ndef) {
 
 
 void OreScatter::generate(Mapgen *mg, u32 blockseed, v3s16 nmin, v3s16 nmax) {
-	if (nmin.Y > height_max || nmax.Y < height_min)
+	int in_range = 0;
+
+	in_range |= (nmin.Y <= height_max && nmax.Y >= height_min);
+	if (flags & OREFLAG_ABSHEIGHT)
+		in_range |= (nmin.Y >= -height_max && nmax.Y <= -height_min) << 1;
+	if (!in_range)
 		return;
-	
+
 	resolveNodeNames(mg->ndef);
 	
 	MapNode n_ore(ore);
 	ManualMapVoxelManipulator *vm = mg->vm;
 	PseudoRandom pr(blockseed);
+	int ymin, ymax;
 	
-	int ymin   = MYMAX(nmin.Y, height_min);
-	int ymax   = MYMIN(nmax.Y, height_max);
+	if (in_range & ORE_RANGE_MIRROR) {
+		ymin = MYMAX(nmin.Y, -height_max);
+		ymax = MYMIN(nmax.Y, -height_min);
+	} else {
+		ymin = MYMAX(nmin.Y, height_min);
+		ymax = MYMIN(nmax.Y, height_max);
+	}
 	if (clust_size >= ymax - ymin + 1)
 		return;
 	
@@ -131,17 +149,29 @@ void OreScatter::generate(Mapgen *mg, u32 blockseed, v3s16 nmin, v3s16 nmax) {
 
 
 void OreSheet::generate(Mapgen *mg, u32 blockseed, v3s16 nmin, v3s16 nmax) {
-	if (nmin.Y > height_max || nmax.Y < height_min)
-		return;
+	int in_range = 0;
 
+	in_range |= (nmin.Y <= height_max && nmax.Y >= height_min);
+	if (flags & OREFLAG_ABSHEIGHT)
+		in_range |= (nmin.Y >= -height_max && nmax.Y <= -height_min) << 1;
+	if (!in_range)
+		return;
+		
 	resolveNodeNames(mg->ndef);
 
 	MapNode n_ore(ore);
 	ManualMapVoxelManipulator *vm = mg->vm;
 	PseudoRandom pr(blockseed + 4234);
+	int ymin, ymax;
 	
-	int ymin = MYMAX(nmin.Y, height_min);
-	int ymax = MYMIN(nmax.Y, height_max);
+	if (in_range & ORE_RANGE_MIRROR) {
+		ymin = MYMAX(nmin.Y, -height_max);
+		ymax = MYMIN(nmax.Y, -height_min);
+	} else {
+		ymin = MYMAX(nmin.Y, height_min);
+		ymax = MYMIN(nmax.Y, height_max);
+	}
+
 	if (clust_size >= ymax - ymin + 1)
 		return;
 		

src/mapgen.h

@@ -36,7 +36,17 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #define MGV6_BIOME_BLEND 0x10
 #define MG_FLAT          0x20
 
+/////////////////// Ore generation flags
+// Use absolute value of height to determine ore placement
+#define OREFLAG_ABSHEIGHT 0x01 
+// Use 3d noise to get density of ore placement, instead of just the position
+#define OREFLAG_DENSITY   0x02 // not yet implemented
+// For claylike ore types, place ore if the number of surrounding
+// nodes isn't the specified node
+#define OREFLAG_NODEISNT  0x04 // not yet implemented
+
 extern FlagDesc flagdesc_mapgen[];
+extern FlagDesc flagdesc_ore[];
 
 class BiomeDefManager;
 class Biome;
@@ -103,6 +113,9 @@ enum OreType {
 	ORE_CLAYLIKE
 };
 
+#define ORE_RANGE_ACTUAL 1
+#define ORE_RANGE_MIRROR 2
+
 class Ore {
 public:
 	std::string ore_name;
@@ -115,6 +128,7 @@ public:
 	s16 clust_size;     // how large (in nodes) a chunk of ore is
 	s16 height_min;
 	s16 height_max;
+	u32 flags;          // attributes for this ore
 	float nthresh;      // threshhold for noise at which an ore is placed 
 	NoiseParams *np;    // noise for distribution of clusters (NULL for uniform scattering)
 	Noise *noise;

src/scriptapi.cpp

@@ -717,6 +717,7 @@ static int l_register_ore(lua_State *L)
 	ore->clust_size     = getintfield_default(L, index, "clust_size", 0);
 	ore->height_min     = getintfield_default(L, index, "height_min", 0);
 	ore->height_max     = getintfield_default(L, index, "height_max", 0);
+	ore->flags          = getflagsfield(L, index, "flags", flagdesc_ore);
 	ore->nthresh        = getfloatfield_default(L, index, "noise_threshhold", 0.);
 
 	lua_getfield(L, index, "noise_params");

src/scriptapi_types.cpp

@@ -336,6 +336,13 @@ void setboolfield(lua_State *L, int table,
 	lua_setfield(L, table, fieldname);
 }
 
+u32 getflagsfield(lua_State *L, int table,
+		const char *fieldname, FlagDesc *flagdesc) {
+	std::string flagstring;
+	
+	flagstring = getstringfield_default(L, table, fieldname, "");
+	return readFlagString(flagstring, flagdesc);
+}
 
 /* minetest specific types */
 MapNode readnode(lua_State *L, int index, INodeDefManager *ndef)

src/scriptapi_types.h

@@ -51,6 +51,8 @@ bool               getboolfield(lua_State *L, int table,
                              const char *fieldname, bool &result);
 bool               getfloatfield(lua_State *L, int table,
                              const char *fieldname, float &result);
+u32                getflagsfield(lua_State *L, int table,
+                             const char *fieldname, FlagDesc *flagdesc);
 
 std::string        checkstringfield(lua_State *L, int table,
                              const char *fieldname);