Inventory

Overview

This article describes how to set up inventory items and how they can be given to an entity. The purpose of the inventory is, to keep track of all items that are in an entities possessions. I delibaretly use "entity" here because, in principle, all entities can have an inventory, even though it may only make sense for AI and the player to actuall have one. For future improvements it might be usefull for other purposes as well though. Also included is a script interface, so that a mapper can interact with the inventory in a more sophisticated way, if the default implementation is not sufficient.

Definitions

The spawnargs can be either set in the def file as a default, or in the map file to override settings for specific entities. Naturaly this also means that they can be manipulated by scripts as well, since they are the standard way of configuring objects in Doom 3.

IMPORTANT!!! Normally items will vanish from the map as soon as the item is successfully put into the inventory. If this doesn't work, then the item will stay visible. This is a intentionally so, to make the mapper aware of the problem. Currently there is only one error condition that can really trigger this, which is that an item is configured to not be anonymous, but has an empty inv_icon entry.

There are several terms and types of items that can be used in the inventory:

• anonymous items An anonymous object means that it will not show up as a seperate item in the inventory. An example would be normal loot like coins or golden dishes. Since they should not be stored in the inventory as seperate items, they don't need to be displayed either. In this case they only count for the total of loot and are discarded afterwards. Anonymous items also can not be dropped after they went into the inventory because they essentially no longer exist. For the loot count it obviously doesn't matter wether an item is anonymous or not, as all are added up into the loot categories. Examples are gold coins and all the other (mostly loot) items that are collected but not being used individually.

• stackable items These are items that can be stacked in the inventory. This means that the player can acquire multiple instances of such items, but only one entry is shown in the inventory with a counter of how many currently are available. An example would be a health potion. The player can posses more than one health potion at a time and this would be indicated by the counter. Stackable items are identified by setting the stackable property. They also must always use the same name and category. If this doesn't match, they are considered to be of different types. This also allows for dealing out i.e. fake health potions which have no effect or deal damage instead (as an example).

• Category is a classification of items, to visually group them together. This allows the player to faster scroll through the inventory because he doesn't have to cycle through all the individual items. For example a category would be 'Readables' where books and scrolls are stored, and another Category would be 'Tools' where lockpicks and other items can be stored. Note that this category is entirely up to the mapper to decide and also is option. it doesn't has any consequence as to the playabillity and is only a convenience for the player. Categories can switched of on the HUD, so that the player can use the inventory also in the Thief style (which is the default).

Spawnargs

  inv_category : string
  Specifies the cagtegory that the object should be filed under. This 
  allows for player convenience and also is needed for stackable items.
  example: "inv_name" "Health Potion"

  inv_name : string
  Specifies the name the object should display when it is activated in the inventory.
  example: "inv_name" "Health Potion"

  inv_icon : D3 path to icon
  Points to an icon that is to be displayed when the object is selected in the inventory.
  This entry also determines wether an object is to be considered anonymous or not. 

  inv_stackable : [0/1]
  Determines wether an item is an individual or can be a stack of similar objects. An
  Example would be the various potions. The player can pick up more than one health 
  potion, but in the inventory he will only get one item with a counter. Keep in mind
  though that a stack of gold coins is not per se stackable, because usually it will be
  only one model of a stack of coin with a value of i.E. 10 Gold, so this means that it
  is not to be confused with a a single gold coin having 10 items with a value of 1 each.

  inv_count : <N>
  Determines the number of items this represents. This is only needed for items where
  stackable is 1, otherwise it is set to 0. Als the option for stackable must always 
  precede the count, otherwise the count is set to 0.

  inv_droppable : [0/1]
  If set to 1 the item can be dropped into the map by the player. This will not
  work for anonymous items, since they will have no representation after they
  were put into the inventory.

  inv_delete : [0/1]
  Determines if an anonymous object can be deleted, after it was put into the inventory.
  This is advisable, because the entity will stay in memory and a mapper could still
  access it via scripting. If the mapper decides that an item will no longer be accessed
  after it has been acquired, this key should be set to 1. This can affect loading time
  of saved games, as entities, that are no longer needed, don't need to be saved and
  restored.
  If the mapper also creates entities on the fly, with the help of scripts, it might
  better to set this flag on appropriate objects to free up the limited number of
  entities a map can hold. The usuals candidates for this flag are all the regular loot
  items, because they wont be used anymore after they have been found (lik coins, purses,
  etc.). Also note that, if dropappable is set to 1, then this key will be ignored, since
  droppabale items must be turned into entities again to be placed in the map.

  inv_loot_type : [ 0 | 1 | 2 | 3 ]
  * 0 = No lootitem (default)
  * 1 = Jewelry/Gems
  * 2 = Gold
  * 3 = Goods
  This has to be set in order to define what kind of item it is and if it is a loot item,
  which category of loot it should account for.

  inv_loot_value : <N>
  Determines the amount of loot this item accounts for. This value is ignore if it is
  set on an item, which is of loot_type = 0.

  inv_map_start : [0|1]
  Determines wether this object should be assigned to an inventory at map start.

  inv_target : <entityname>
  If the item should be assigned to an entity at map start, this should get the name
  of the entity who shold recive it. To give an item to the player, you would use
  "player1" as the name, because this is the name that the player entity gets by
  default. If inv_map_start is not set or set to 0, then this key doesn't need to be
  set and is ignored. Since the name can be arbitrary, this means of course, that you
  can also give it to an AI, which the player later on meets. This should not be confused
  with loot, that is to be attached to an AI though. If you attach a purse or a key to
  an AI, which the player can frob later on, then it doesn't need to get this set, because
  such things will not be stored in the inventory. You could assign such things to an
  chest though, to give the objects to the player when he opens it. This is not directly
  support though, because it is assumed that chests will be filled with real objects, like
  TDS did it. However the T1/T2 style chests are still possible to do with some scripting.

Default equipment for map start

This describes how to give items to the player at the mapstart, but the same mechanism can be applied to any other AI (or entity for that matter) as well.

• First create your object in the editor, just like you would if you wanted to put it in the map. Create brush, select the item and/or models and place it anywhere you like in the map

• Set the key inv_map_start on the object entity to the value 1.

• Set the key inv_target on the object entity to the value player1. If you want to assign this object to, as an example, a guard with the name Benny, then set it to benny, assuming the entity key "name" is also set to "benny".

The objects can really be placed anyhwere you like and it doesn't really matter. As soon as the map starts, the objects will be put in the inventory, and will vanish from the map. So you could put them right in front of the players eyes, and he still wouldn't see them, as this happens at the intialization time, before the map actually becomes visible.

That's it. Quite simple I would say. :)