1 files changed, 125 insertions, 0 deletions
diff --git a/utils.lua b/utils.lua
new file mode 100644
index 0000000..b6a7ef9
--- /dev/null
+++ b/utils.lua
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+-- misc. utilities
+
+-- returns a list of directions to where this cell in a structure is at the structure border.
+-- returns an empty list for inner nodes
+-- horizontal_only restricts search to only the horizontal plane (no y)
+function cellworld.get_border_sides(rel_pos, str_size, horizontal_only)
+	local borders = {}
+	
+	if rel_pos.z == str_size.z-1 then
+		borders[#borders+1] = cellworld.NORTH
+	end
+	if rel_pos.x == str_size.x-1 then
+		borders[#borders+1] = cellworld.EAST
+	end
+	
+	if rel_pos.z == 0 then
+		borders[#borders+1] = cellworld.SOUTH
+	end
+	if rel_pos.x == 0 then
+		borders[#borders+1] = cellworld.WEST
+	end
+	
+	if not horizontal_only then
+		if rel_pos.y == str_size.y-1 then
+			borders[#borders+1] = cellworld.UP
+		end
+		if rel_pos.y == 0 then
+			borders[#borders+1] = cellworld.DOWN
+		end
+	end
+	
+	return borders
+	
+end
+
+cellworld.opposite_directions = {
+	[cellworld.EAST] = cellworld.WEST,
+	[cellworld.WEST] = cellworld.EAST,
+	[cellworld.NORTH]= cellworld.SOUTH,
+	[cellworld.SOUTH]= cellworld.NORTH,
+	[cellworld.UP]   = cellworld.DOWN,
+	[cellworld.DOWN] = cellworld.UP,
+}
+
+cellworld.direction_to_vector = {
+	[cellworld.EAST] = vector.new(1,0,0),
+	[cellworld.WEST] = vector.new(-1,0,0),
+	[cellworld.NORTH]= vector.new(0,0,1),
+	[cellworld.SOUTH]= vector.new(0,0,-1),
+	[cellworld.UP]   = vector.new(0,1,0),
+	[cellworld.DOWN] = vector.new(0,-1,0),
+}
+
+-- quickly hash a position. Only suitable for relative positions, limited to a range of 0..255 each coordinate
+function cellworld.small_pos_hash(x,y,z)
+	return y*65536 + x*256 + z
+end
+
+-- returns the relative structure cell definition
+function cellworld.get_structure_cell(struct, relpos)
+	if struct.cells then
+		local pstr = relpos.x.."|"..relpos.y.."|"..relpos.z
+		if struct.cells[pstr] then
+			return struct.cells[pstr]
+		end
+	end
+	return struct.cell
+end
+
+cellworld.pcgrandom = PcgRandom(os.time())
+
+function cellworld.random(min, max)
+	return cellworld.pcgrandom:next(min,max)
+end
+
+-- returns random element from the list
+function cellworld.select_random_element(list)
+	local r = cellworld.random(1, #list)
+	return list[r]
+end
+
+-- returns a for iterator that iterates from 'from' to 'to' integers but in random order
+function iterate_random_order(from, to)
+	local list = {}
+	for i=from,to do
+		list[#list+1] = i
+	end
+	return function()
+		if #list==0 then return nil end
+		local r = cellworld.random(1, #list)
+		return table.remove(list, r)
+	end
+end
+
+function cellworld.v_decompose(vec)
+	return vec.x, vec.y, vec.z
+end
+
+-- convert back and forth
+function cellworld.world_to_cell_pos(wpos)
+	if not cellworld.grid_size then
+		error("Grid size hasn't been configured yet, is a structure set loaded?")
+	end
+	return vector.new(
+		math.floor(wpos.x / cellworld.grid_size),
+		math.floor(wpos.y / cellworld.grid_size),
+		math.floor(wpos.z / cellworld.grid_size)
+	)
+end
+
+-- upper: output the upper corner of the cell
+function cellworld.cell_to_world_pos(cpos, upper)
+	if not cellworld.grid_size then
+		error("Grid size hasn't been configured yet, is a structure set loaded?")
+	end
+	local wi=0
+	if upper then
+		wi = cellworld.grid_size-1
+	end
+	return vector.new(
+		cpos.x * cellworld.grid_size + wi,
+		cpos.y * cellworld.grid_size + wi,
+		cpos.z * cellworld.grid_size + wi
+	)
+end