-- These functions are a minor modification of the voxel area iterator defined in the built in voxelarea.lua lua code.
-- As such, this file is separately licened under the LGPL as follows:

-- License of Minetest source code
-------------------------------

--Minetest
--Copyright (C) 2010-2018 celeron55, Perttu Ahola <celeron55@gmail.com>

--This program is free software; you can redistribute it and/or modify
--it under the terms of the GNU Lesser General Public License as published by
--the Free Software Foundation; either version 2.1 of the License, or
--(at your option) any later version.

--This program is distributed in the hope that it will be useful,
--but WITHOUT ANY WARRANTY; without even the implied warranty of
--MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
--GNU Lesser General Public License for more details.

--You should have received a copy of the GNU Lesser General Public License along
--with this program; if not, write to the Free Software Foundation, Inc.,
--51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

function VoxelArea:iter_xyz(minx, miny, minz, maxx, maxy, maxz)
    local i = self:index(minx, miny, minz) - 1

    local x = minx - 1 -- subtracting one because x gets incremented before it gets returned the first time.
    local xrange = maxx - minx + 1
    local nextaction = i + 1 + xrange

    local y = 0
    local yrange = maxy - miny + 1
    local yreqstride = self.ystride - xrange

    local z = 0
    local zrange = maxz - minz + 1
    local multistride = self.zstride - ((yrange - 1) * self.ystride + xrange)

    return function()
        -- continue i until it needs to jump
        i = i + 1
        x = x + 1
        if i ~= nextaction then
            return i, x, y+miny, z+minz
        end

        -- continue y until maxy is exceeded
        y = y + 1
        x = minx -- new line
        if y ~= yrange then
            -- set i to index(minx, miny + y, minz + z) - 1
            i = i + yreqstride
            nextaction = i + xrange
            return i, x, y+miny, z+minz
        end

        -- continue z until maxz is exceeded
        z = z + 1
        if z == zrange then
            -- cuboid finished, return nil
            return
        end

        -- set i to index(minx, miny, minz + z) - 1
        i = i + multistride

        y = 0
        nextaction = i + xrange
        return i, x, y+miny, z+minz
    end
end

function VoxelArea:iterp_xyz(minp, maxp)
    return self:iter_xyz(minp.x, minp.y, minp.z, maxp.x, maxp.y, maxp.z)
end