plantlife_modpack/API.txt

This document briefly describes the Plantlife API.

=========
Functions
=========

There are five main functions defined by the main "plants_lib" mod:

spawn_on_surfaces()
grow_plants()
plant_valid_wall()
is_node_loaded()
dbg()

-----
The first of these, spawn_on_surfaces() is defined with quite a large number
of variables.  All of the variables below, if specified at all, must be
specified exactly in the order given here.  This function has no return value.

spawn_on_surfaces = function(sdelay, splant, sradius, schance, ssurface,
		    savoid, seed_diff, lightmin, lightmax, nneighbors, ocount,
			facedir, depthmax, altitudemin, altitudemax, tempmin, tempmax)

The first several of these are all required, and are from the last version of
the flowers mod, so this part of the API should be the same as before.

sdelay:				The value passed to the ABM's interval parameter, usually
					in the 1000-3000 range.
splant:				The node name of the item to spawn (e.g.
					"flowers:flower_rose").  Note that if the plant is
					"poisonivy:seedling", and it's next to a wall at spawn
					time, it automatically becomes the wall-climbing variety.
					A plant will of course only be spawned if the node about
					to be replaced is air.
sradius:			Don't spawn within this many nodes of the avoid items
					mentioned below.
schance:			The value passed to the ABM's chance parameter, normally
					in the 10-100 range.
ssurface:			Table with the names of the nodes on which to spawn the
					plant in question, such as {"default:sand",
					"default:dirt_with_grass"}.  It is not recommended to put
					"default:dirt" or "default:stone" into this table if you
					can do without it, as this will cause the engine to
					process potentially large numbers of such nodes when
					deciding when to execute the ABM and where it should
					operate.
savoid:				Table with a list of groups and/or node names to avoid
					when spawning the plant, such as {"group:flowers",
					"default:tree"}.

From here down are several optional parameters.  You can use as many as you
need, but you must specify them in order (so if you want lightmax, you need
lightmin and seed_diff also, but not the rest).

seed_diff:			The Perlin seed difference value passed to the
					minetest.env:get_perlin() function.  Used along with the
					global Perlin controls below to create the "biome" in
					which the plants will spawn.  Usually a value of somewhere
					in the 10 to 100 range is good.  Defaults to 0 if not
					provided.
lightmin:			Minimum amount of light necessary to make a plant spawn.
					Defaults to 0.
lightmax:			Maximum amount of light present to allow a plant to spawn. 
					Defaults to the engine's MAX_LIGHT value of 14.
nneighbors:			Table with a list of neighboring nodes, passed to the ABM
					as the "neighbors" parameter, indicating what needs to be
					next to the node the plant is about to spawn on, such as
					{"default:stone","default:water_source"}.  Defaults to the
					value of ssurface if not provided.
ocount:				There must be at least this many of the above neighbors in
					the eight spaces immediately surrounding the node the
					plant is about to spawn on for it to happen.  Defaults to
					0.
facedir:			The value passed to the param2 variable when adding the
					plant node to the map.  Defaults to 0.
depthmax:			If a node spawns on top of a water source, the water must
					be at most this deep.  Defaults to 1 node.
altitudemin:		Items must be at this altitude or higher to spawn at all.
					Defaults to -31000.
altitudemax:		But no higher than this altitude.  Defaults to +31000.
sbiome:				List of nodes that must be somewhere in the vicinity in
					order for the plant to spawn.  Typically this would be 
					something like "default:water_source" or "default:sand".
					Defaults to the value of ssurface if not provided.
sbiomesize:			How large of an area to check for the above node.
					Specifically, this checks a cuboid area centered on the
					node to be spawned on, 3 tall and this wide/long.
					Defaults to 0.
sbiomecount:		How many of the above nodes must be within that radius.
					Defaults to 1.
airradius:			How large of an area to check for air around the target.
					Defaults to 0 (only check the target).
aircount:			How many of the surrounding nodes need to be air for the
					above check to return true.  Defaults to 1.
tempmin:			Minimum 2d Perlin value (which has a floating point range of
					-1 to +1) needed in the temperature map for the desired
					plant to spawn.  Defaults to -1 if not supplied.
tempmax:			Maximum temperature.  Defaults to +1.

By default, if a biome node, size, and count are not defined, the biome
checking is disabled.  Same holds true for the nneighbors bit above that.

-----
The second function, grow_plants() is used to turn the spawned nodes above
into something else over time.  This function has no return value, and is
defined like so:

grow_plants = function(gdelay, gchance, gplant, gresult, dry_early_node,
		grow_nodes, facedir, need_wall, grow_vertically, height_limit,
		ground_nodes, grow_function)

gdelay:				Passed as the ABM "interval" parameter, as with spawning.
gchance:			Passed as the ABM "chance" parameter.
gplant:				Name of the node being grown.  This value is passed as the 
					only item in the table given to the ABM as the nodenames
					parameter, so it is the plants themselves that are the ABM
					trigger, rather than the ground they spawned on.  A plant
					will only grow if the node above it is air.
gresult:			Name of the node into which the above should transform
					when the ABM executes.
dry_early_node:		This value is ignored except for jungle grass, where it
					indicates which node the grass must be on in order for it
					to turn from "short" to default:dry_shrub.
grow_nodes:			This node must be under the plant in order for it to grow
					at all.  Normally this should be the same as the list of 
					surfaces passed to the spawning ABM as the "nodenames"
					parameter, such as {"default:dirt_with_grass",
					"default:sand"}.  This is so that the plant can be
					manually placed on something like a flower pot or
					something without it growing and eventually dieing.
facedir:			Same as with spawning a plant.  If supplied, this value is
					passed to the param2 variable when changing the plant.  If
					nil or left out, no new param2 value is applied.
need_wall:			Set this to true if you the plant needs to grow against a
					wall.  Defaults to false.
grow_vertically:	Set this to true if the plant needs to grow vertically, as
					in climbing poison ivy.  Defaults to false.
height_limit:		Just how tall can a vertically-growing plant go?  Set this
					accordingly.  The mod will search straight down from the
					position being spawned at to find a ground node, below.
					Defaults to 62000 (unlimited).
ground_nodes:		What nodes should be treated as "the ground" below a
					vertically-growing plant.  Usually this will be the same
					as the grow_nodes table, but might also include, for
					example, water or some other surrounding material.
					Defaults to "default:dirt_with_grass".
grow_function:		Execute the named function (which must be supplied as just
					the name of the function as a string) when growing this
					node, rather than using the method provided by the default
					growing code.  Note that if this is specified, only the
					gdelay, gchance, and gplant variables will be used, the
					rest will be ignored by the growing ABM.  You can still
					read them from within the function if you need to.  The
					function will be passed two parameters in order:  The
					position of the node to be "grown" (in the usual table
					format), and the Perlin noise value at the location in
					question.
seed_diff:			The Perlin seed diff to be use to calculate the noise 
					value given to the above grow_function.  Should be the
					same as the seed diff used when first spawning the plant
					that's being grown.

-----
plant_valid_wall() expects only a single parameter, "pos", which is the usual
table indicating the coordinates around which to search for adjacent walls.
This function returns the location of the first wall found as a facedir value,
or nil if there are no adjacent walls.

-----
is_node_loaded() is defined in exactly the same manner (that is, "node_pos" is
a set of coordinates), and acts as a wrapper for the
minetest.env:get_node_or_nil(node_pos) function.  Returns true if the node in
question is already loaded, or false if not.

-----
dbg() is a simple debug output function which takes one string parameter.  It
just checks if plantlife_debug is true and outputs the phrase "[Plantlife] "
followed by the supplied string, via the print() function.


===============
Global Settings
===============

Enable this if you want the mod to spam your console with debug info :-)

	plantlife_debug = false

The mod uses Perlin noise to create "biomes" of the various plants.  Aside
from plantlife_seed_diff (see below), these values are the ones plugged 
directly into the minetest.env:get_perlin() function.  For more information on
how Perlin noise is generated, you will need to search the web, as these
default values were arrived at through trial and error.

	plantlife_seed_diff = 123
	perlin_octaves = 3
	perlin_persistence = 0.2
	perlin_scale = 25

This value is compared against the output of the above Perlin noise function
to decide when to actually place a plant.  Smaller numbers mean larger biomes
and more abundant plants.

	plantlife_limit = 0.6

These three are pretty obvious.  Basically they control the shape and 
distribution of the biomes in which the various plants will appear.

	flowers_seed_diff = plantlife_seed_diff
	junglegrass_seed_diff = plantlife_seed_diff + 10
	poisonivy_seed_diff = plantlife_seed_diff + 10

==============
Local settings
==============

Each of the three components of this modpack has an init.lua file, as usual,
and at the top of those files are four variables that affect how and when the
ABMs are run.  In each one, the spawn_delay value is used as the 'interval'
parameter and controls how often to run the ABM (in in-game tenths of
seconds), while spawn_chance is used for the ABM's "chance" parameter, and is
basically how likely the ABM is to actually execute (a 1 to (1/chance)
probability).

	spawn_delay = 2000
	spawn_chance = 100

The other two in each init.lua file control the same two settings used by the
growing ABM.

	grow_delay = 1000
	grow_chance = 10

===================
Temperature Mapping
===================

This mod uses Perlin noise to establish a rough temperature map, with values
taken from Splizard's Snow Biomes mod so that the two will be compatible,
since that mod appears to be the standard now.

The way Perlin values are used by this mod, in keeping with the snow mod's 
apparent methods, larger values returned by the Perlin function represent
*colder* temperatures.  In this mod, the following table gives a rough
approximation of how temperature maps to these values, normalized to
0.53 = 0 °C and +1.0 = -25 °C.

Perlin		Approx. Temperature
-1.0		 81 °C	( 178 °F)
-0.75		 68 °C	( 155 °F)
-0.56		 58 °C	( 136 °F)
-0.5		 55 °C	( 131 °F)
-0.25		 41 °C	( 107 °F)
-0.18		 38 °C	( 100 °F)
 0			 28 °C	(  83 °F)
 0.13		 21 °C	(  70 °F)
 0.25		 15 °C	(  59 °F)
 0.5		  2 °C	(  35 °F)
 0.53		  0 °C	(  32 °F)
 0.75		-12 °C	(  11 °F)
 0.86		-18 °C	(   0 °F)
 1.0		-25 °C	(- 13 °F)

Included in this table are even 0.25 steps in Perlin values along with some
common temperatures on both the Centigrade and Fahrenheit scales.  Note that
unless you're trying to model the Moon or perhaps Mercury in your mods/maps, 
you probably won't need to bother with Perlin values of less than -0.56 or so.