init.lua

--[[

Solar Mana mod [solarmana]
==========================

A mana regeneration controller: only regenerate mana in sunlight.

Copyright (C) 2015 Ben Deutsch <ben@bendeutsch.de>

This library 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 library 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 library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
USA

]]


local time_total_regen_check = 0.5
local time_next_regen_check = time_total_regen_check

-- TODO: make this globally accessible
local mana_from_node = {
    ['default:goldblock'] = 0.5,
    ['group:wood'] = 0.2,
    ['default:stone'] = -0.2,
}

-- just for debugging: see below
local time_total_mana_reset = 10.0
local time_next_mana_reset = time_total_mana_reset

minetest.register_globalstep(function(dtime)

    -- We do not care if this does not run as often as possible,
    -- as all it does is change the regeneration to a fixed number
    time_next_regen_check = time_next_regen_check - dtime
    if time_next_regen_check < 0.0 then
        time_next_regen_check = time_total_regen_check
        for _,player in ipairs(minetest.get_connected_players()) do
            local name = player:get_player_name()
            local pos  = player:getpos()
            local pos_y = pos.y
            -- the middle of the block with the player's head
            pos.y = math.floor(pos_y) + 1.5
            local node = minetest.get_node(pos)

            -- Currently uses 'get_node_light' to determine whether
            -- a node is "in sunlight".
            local light_day   = minetest.get_node_light(pos, 0.5)
            local light_night = minetest.get_node_light(pos, 0.0)
            local light_now   = minetest.get_node_light(pos) or 0
            local regen_to = 0

            -- simplest version checks for "full sunlight now"
            if light_now >= 15 then
                regen_to = 1
            end

            -- we can get a bit more lenience by testing whether
            -- * a node is "affected by sunlight" (day > night)
            -- * the node is "bright enough now"
            -- However: you could deny yourself mana regeneration
            --          with torches :-/
            --[[
            if light_day > light_night and light_now > 12 then
                regen_to = 1
            end
            --]]

            -- next, check the block we're standing on.
            pos.y = math.floor(pos_y) - 0.5
            node = minetest.get_node(pos)
            local nodemana = mana_from_node[node.name]
            for key, value in pairs(mana_from_node) do
                if key:split(":")[1] == "group" then
                    local groupname = key:split(":")[2]
                    if minetest.get_node_group(node.name, groupname) > 0 then
                        if nodemana then
                            nodemana = math.max(nodemana, value) -- We get the greater one (if the node is part of 2 or more groups)
                        else
                            nodemana = value
                        end
                    end
                end
            end
            if nodemana then
                if nodemana > 0 then
                    regen_to = math.max(regen_to, nodemana)
                else
                    regen_to = regen_to + nodemana -- negative, remember?
                end
                --print("Regen to "..regen_to.." : "..node.name)
            end


            mana.setregen(name, regen_to)
            --print("Regen to "..regen_to.." : "..light_day.."/"..light_now.."/"..light_night)
        end
    end

    --[[ Comment this in for testing if you have no mana sink

    time_next_mana_reset = time_next_mana_reset - dtime
    if time_next_mana_reset < 0.0 then
        time_next_mana_reset = time_total_mana_reset
        mana.set('singleplayer', 100)
        print("Resetting mana")
    end

    --]]

end)