SAPI/Noise: Add PerlinNoiseMap:getMapSlice() function

This adds the ability to grab 'slices' of noise calculated by PerlinNoiseMap.
Retrieving smaller slices of noise from the computation result as needed
optimizes memory usage while maintaining a reasonable amount of CPU overhead.

4 files changed, 159 insertions, 0 deletions

diff --git a/src/script/common/c_converter.cpp b/src/script/common/c_converter.cpp
index 6fb6f623a..211121552 100644
--- a/src/script/common/c_converter.cpp
+++ b/src/script/common/c_converter.cpp
@@ -510,3 +510,95 @@ void setboolfield(lua_State *L, int table,
 }
 
 
+////
+//// Array table slices
+////
+
+size_t write_array_slice_float(
+	lua_State *L,
+	int table_index,
+	float *data,
+	v3u16 data_size,
+	v3u16 slice_offset,
+	v3u16 slice_size)
+{
+	v3u16 pmin, pmax(data_size);
+
+	if (slice_offset.X > 0) {
+		slice_offset.X--;
+		pmin.X = slice_offset.X;
+		pmax.X = MYMIN(slice_offset.X + slice_size.X, data_size.X);
+	}
+
+	if (slice_offset.Y > 0) {
+		slice_offset.Y--;
+		pmin.Y = slice_offset.Y;
+		pmax.Y = MYMIN(slice_offset.Y + slice_size.Y, data_size.Y);
+	}
+
+	if (slice_offset.Z > 0) {
+		slice_offset.Z--;
+		pmin.Z = slice_offset.Z;
+		pmax.Z = MYMIN(slice_offset.Z + slice_size.Z, data_size.Z);
+	}
+
+	const u32 ystride = data_size.X;
+	const u32 zstride = data_size.X * data_size.Y;
+
+	u32 elem_index = 1;
+	for (u32 z = pmin.Z; z != pmax.Z; z++)
+	for (u32 y = pmin.Y; y != pmax.Y; y++)
+	for (u32 x = pmin.X; x != pmax.X; x++) {
+		u32 i = z * zstride + y * ystride + x;
+		lua_pushnumber(L, data[i]);
+		lua_rawseti(L, table_index, elem_index);
+		elem_index++;
+	}
+
+	return elem_index - 1;
+}
+
+
+size_t write_array_slice_u16(
+	lua_State *L,
+	int table_index,
+	u16 *data,
+	v3u16 data_size,
+	v3u16 slice_offset,
+	v3u16 slice_size)
+{
+	v3u16 pmin, pmax(data_size);
+
+	if (slice_offset.X > 0) {
+		slice_offset.X--;
+		pmin.X = slice_offset.X;
+		pmax.X = MYMIN(slice_offset.X + slice_size.X, data_size.X);
+	}
+
+	if (slice_offset.Y > 0) {
+		slice_offset.Y--;
+		pmin.Y = slice_offset.Y;
+		pmax.Y = MYMIN(slice_offset.Y + slice_size.Y, data_size.Y);
+	}
+
+	if (slice_offset.Z > 0) {
+		slice_offset.Z--;
+		pmin.Z = slice_offset.Z;
+		pmax.Z = MYMIN(slice_offset.Z + slice_size.Z, data_size.Z);
+	}
+
+	const u32 ystride = data_size.X;
+	const u32 zstride = data_size.X * data_size.Y;
+
+	u32 elem_index = 1;
+	for (u32 z = pmin.Z; z != pmax.Z; z++)
+	for (u32 y = pmin.Y; y != pmax.Y; y++)
+	for (u32 x = pmin.X; x != pmax.X; x++) {
+		u32 i = z * zstride + y * ystride + x;
+		lua_pushinteger(L, data[i]);
+		lua_rawseti(L, table_index, elem_index);
+		elem_index++;
+	}
+
+	return elem_index - 1;
+}
diff --git a/src/script/common/c_converter.h b/src/script/common/c_converter.h
index e99826404..e4466d97f 100644
--- a/src/script/common/c_converter.h
+++ b/src/script/common/c_converter.h
@@ -106,4 +106,9 @@ void                warn_if_field_exists(lua_State *L, int table,
                                          const char *fieldname,
                                          const std::string &message);
 
+size_t write_array_slice_float(lua_State *L, int table_index, float *data,
+	v3u16 data_size, v3u16 slice_offset, v3u16 slice_size);
+size_t write_array_slice_u16(lua_State *L, int table_index, u16 *data,
+	v3u16 data_size, v3u16 slice_offset, v3u16 slice_size);
+
 #endif /* C_CONVERTER_H_ */
diff --git a/src/script/lua_api/l_noise.cpp b/src/script/lua_api/l_noise.cpp
index 86ae9dba7..c8dc2d2dc 100644
--- a/src/script/lua_api/l_noise.cpp
+++ b/src/script/lua_api/l_noise.cpp
@@ -272,6 +272,61 @@ int LuaPerlinNoiseMap::l_get3dMap_flat(lua_State *L)
 }
 
 
+int LuaPerlinNoiseMap::l_calc2dMap(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	LuaPerlinNoiseMap *o = checkobject(L, 1);
+	v2f p                = check_v2f(L, 2);
+
+	Noise *n = o->noise;
+	n->perlinMap2D(p.X, p.Y);
+
+	return 0;
+}
+
+int LuaPerlinNoiseMap::l_calc3dMap(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	LuaPerlinNoiseMap *o = checkobject(L, 1);
+	v3f p                = check_v3f(L, 2);
+
+	if (!o->m_is3d)
+		return 0;
+
+	Noise *n = o->noise;
+	n->perlinMap3D(p.X, p.Y, p.Z);
+
+	return 0;
+}
+
+
+int LuaPerlinNoiseMap::l_getMapSlice(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	LuaPerlinNoiseMap *o = checkobject(L, 1);
+	v3s16 slice_offset   = read_v3s16(L, 2);
+	v3s16 slice_size     = read_v3s16(L, 3);
+	bool use_buffer      = lua_istable(L, 4);
+
+	Noise *n = o->noise;
+
+	if (use_buffer)
+		lua_pushvalue(L, 3);
+	else
+		lua_newtable(L);
+
+	write_array_slice_float(L, lua_gettop(L), n->result,
+		v3u16(n->sx, n->sy, n->sz),
+		v3u16(slice_offset.X, slice_offset.Y, slice_offset.Z),
+		v3u16(slice_size.X, slice_size.Y, slice_size.Z));
+
+	return 1;
+}
+
+
 int LuaPerlinNoiseMap::create_object(lua_State *L)
 {
 	NoiseParams np;
@@ -339,8 +394,11 @@ const char LuaPerlinNoiseMap::className[] = "PerlinNoiseMap";
 const luaL_reg LuaPerlinNoiseMap::methods[] = {
 	luamethod(LuaPerlinNoiseMap, get2dMap),
 	luamethod(LuaPerlinNoiseMap, get2dMap_flat),
+	luamethod(LuaPerlinNoiseMap, calc2dMap),
 	luamethod(LuaPerlinNoiseMap, get3dMap),
 	luamethod(LuaPerlinNoiseMap, get3dMap_flat),
+	luamethod(LuaPerlinNoiseMap, calc3dMap),
+	luamethod(LuaPerlinNoiseMap, getMapSlice),
 	{0,0}
 };
 
diff --git a/src/script/lua_api/l_noise.h b/src/script/lua_api/l_noise.h
index 56d2d59f8..e958c5a23 100644
--- a/src/script/lua_api/l_noise.h
+++ b/src/script/lua_api/l_noise.h
@@ -74,6 +74,10 @@ class LuaPerlinNoiseMap : public ModApiBase {
 	static int l_get3dMap(lua_State *L);
 	static int l_get3dMap_flat(lua_State *L);
 
+	static int l_calc2dMap(lua_State *L);
+	static int l_calc3dMap(lua_State *L);
+	static int l_getMapSlice(lua_State *L);
+
 public:
 	LuaPerlinNoiseMap(NoiseParams *np, int seed, v3s16 size);