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Getting Started with AGS - Part 5

Managing Inventory

Each character in the game can carry their own set of inventory items. Inventory items are totally separate from room objects, and you must explicitly set up every item which the player can carry at some point in the game.

Go to the "Inventory items" node in the project tree. We visited this briefly in part 4, but it's time to go into a bit more detail. 

The inventory editor, another look

Every inventory item that the player can carry at some point during the game is listed in the project tree. All the items there also have a number beside them - this is the inventory item ID, which is largely for backwards compatibility with older versions of AGS.

To edit an inventory item, double-click it in the project tree, and a new window will open up with the item's properties in the property grid. If you want the player character to start off carrying the selected item, set the "PlayerStartsWithItem" option to True. Remember, if you want to change which image is used for the item, select the "Image" property and click the "..." button.

Now, you may have noticed that once the player had picked up the key in our game, they could see it in their inventory window but not actually do anything to it - clicking Look or Use on the item did nothing.

In order to give the inventory item some interactivity, we once again need to call on the Events List. Click the "Events" (lightning) button to bring it up:

The events list... this time for inventory

Now, the important point to note here is that if you are using the built-in inventory window (which we are), the only events which can occur are "Look at inventory item" and "Use inventory on this item". This is because the default inventory window only has Look and Select options. The other modes are all available if you design your own inventory GUI (but that's quite complex so we'll leave it for later).

So, select the "Look at inventory item" event, and click the "..." button. You'll be taken to the script editor once more, but this time you'll notice that there's already some existing script as well as our new method:

Script for looking at the key

We are now editing the global script. This has all the script for handling events on game-wide things like inventory items and characters. Previously we were working with hotspots and objects, so they were confined to their own room script.

Anyway, for now I've just added a simple Display command to show the player a message when they look at the key. Feel free to do something similar.

Inventory item hotspots

By default, when the player selects an inventory item as their mouse cursor and clicks on the screen with it, the centre of the item will be used to decide what to activate. However, with some items you may well not want this behaviour - for example, we might want the end of our key to be the activation spot.

To set the cursor hotspot, simply click on the spot within the image. You should see a crosshair appear where you clicked.

The "Draw crosshair" option, if activated, will draw a spot on this part of the item in-game so that the player can easily tell which bit of the cursor is active. You can set the inner and outer colours for the crosshair.

Recap

• Inventory items are not objects. The two are totally seperate, although often picking up an object will give the player an inventory item.
• Each character has their own inventory. If you are making a game like Day of the Tentacle, where the player can switch between characters, then they will each have their own set of inventory items. Usually, you'll use inventory commands to operate on the current player character.

• To give the player an inventory item, use the player.AddInventory command.

Go to part 6: Using your own graphics

Tutorial last updated 17 August 2007. Copyright (c) 2001-2007 Chris Jones.