Placing blocks in lua

[NiLSPACE]

Then you probably want something like this:

-- g_Areas - An array containing cuboid objects. We assume all cuboids have their coordinates sorted.
-- world - The cWorld object where all modifications will be taking place
-- g_CoolDownPeriodTicks - The amount of ticks before the areas should be replaced again.

function ReplaceAllBlocks()
	-- Assuming area is a cCuboid
	for idx, area in ipairs(g_Areas) do
		local blockArea = cBlockArea();
		blockArea:Read(world, area);
		local sizeX, sizeY, sizeZ = blockArea:GetCoordRange()
		for relX = 0, sizeX do
			for relY = 0, sizeY do
				for relZ = 0, sizeZ do
					if (blockArea:GetRelBlockType(relX, relY, relZ) == E_BLOCK_STONE) then
						blockArea:SetRelBlockType(relX, relY, relZ, E_BLOCK_DIRT)
					end
				end
			end
		end
		blockArea:Write(world, area.p1)
	end
	world:ScheduleTask(g_CoolDownPeriodTicks, world)
end

You can add new areas by putting them into g_Areas. Currently only one world is used, but it shouldn't be hard to make this work for multiple worlds.