Minetest-WorldEditAdditions/worldeditadditions_commands/commands/selectors/srect.lua

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-- ███████ ██   ██ ███████  ██████    ██
worldedit.register_command("srect", {
	params = "[<axis1> [<axis2>]] <length>",
	description = "Set WorldEdit region position 2 at a set distance along 2 axes.",
	privs = { worldedit = true },
	require_pos = 1,
	parse = function(params_text)
		local wea = worldeditadditions
		local find = wea.split(params_text, "%s", false)
		local ax1, ax2, len = find[1], find[2], find[table.maxn(find)]
		
		-- If ax1 is bad set to player facing dir
		if ax1 == len or not ax1:match('[xyz]') then ax1 = "get"
		else
			local success, value = wea.getsign(ax1, "int")
			if not success then return success, value
			else ax1 = { value, ax1:gsub('[^xyz]', ''):sub(1, 1) } end
		end
		-- If ax2 is bad set to +y
		if not ax2 or ax2 == len or not ax2:match('[xyz]') then ax2 = "y" end
		local success, value = wea.getsign(ax2, "int")
		if not success then return success, value end
		ax2 = { value, ax2:gsub('[^xyz]', ''):sub(1, 1) }
		
		len = tonumber(len)
		-- If len == nill cancel the operation
		if len == nil then
			return false, "No length specified."
		end
		
		return true, ax1, ax2, len
	end,
	func = function(name, axis1, axis2, len)
		if axis1 == "get" then axis1 = worldeditadditions.player_axis2d(name) end
		
		local p2 = vector.new(worldedit.pos1[name])
		
		p2[axis1[2]] = p2[axis1[2]] + tonumber(len) * axis1[1]
		p2[axis2[2]] = p2[axis2[2]] + tonumber(len) * axis2[1]
		
		worldedit.pos2[name] = p2
		worldedit.mark_pos2(name)
		return true, "position 2 set to " .. minetest.pos_to_string(p2)
	end,
})

-- Tests
-- /multi //fp set1 -63 19 -20 //srect 5
-- /multi //fp set1 -63 19 -20 //srect z 5
-- /multi //fp set1 -63 19 -20 //srect a z 5
-- /multi //fp set1 -63 19 -20 //srect z a 5
-- /multi //fp set1 -63 19 -20 //srect -z 5
-- /multi //fp set1 -63 19 -20 //srect a -x 5
-- /multi //fp set1 -63 19 -20 //srect -x -a 5