Getting Started with AGS - Part 4

Objects

Objects are images on the screen which, unlike the screen background, can move, change and disappear. You use objects for things in the room that the player can take (since they can disappear), and for things which need to animate.

So, let's revisit the age-old "key" inventory item. Let's say we've got a locked door, and the player can pick up a key from another room to open it with. Please don't use this puzzle when you're making a proper game, it's been done far too many times ;-)

Go to the Objects pane under the Room Editor. Click the "New object" button at the top of the screen. Nothing will seem to happen, but you now click on the background image, and a new object will be placed there as a blue cup. Don't worry if you don't put it in the right place, you can move it later.

The first thing we need to do is to change how it looks. That blue cup we can see is the default sprite in AGS, and will appear anywhere that you haven't chosen a replacement for. Click the "Change image" button in the top part of the screen.

The screen will now change to present you with the Sprite Manager. We'll explain this in more detail later, but basically it is the focal point of AGS where you import and export all the graphics (except room backgrounds). You should see a small key picture as sprite number 2. Double-click that for now, we'll import our own graphics later.

You should now be returned to the Objects pane, and see that the blue cup has changed into a key. You can move it around by left-clicking and dragging the sprite within the background image. Place it somewhere sensible on your screen. Also, notice in the top part of the editor is an "Object name" box. This allows you to name the item, similar to the Hotspot Name box for hotspots.

I've placed the key cunningly in the middle of the walkway ;-)

Before we enable the key to be taken by the player, let me quickly go over the other options on this screen:

Lock this object in position - sometimes, you might have two objects that are overlapping each other. In this case, you can lock one of the objects, which prevents it from being selected and dragged. The Lock setting is only temporary and is not saved in your game files, as it's only needed briefly in order to get at an object that's stuck behind another.
Set baseline - normally, the baseline for an object is set to the bottom of the object graphic (baselines are used to calculate which items on the screen are drawn in front and which are drawn at the back). However, in some cases you might want to override this.
What you'll notice with our key is that if the player walks just behind it, the key will appear in front of his feet. This is not what we want, since the key is supposed to be lying flat on the ground. To correct this, click Set Baseline, then click near the top of the room image. A blue line will be drawn across. This will make sure that the player is always drawn in front of the key.
Object is initially visible - this toggles whether the object is switched on at the beginning of the game or not. For our key we want it checked, but sometimes you'll have objects which you don't want the player to see until they've done something else in the game.

The game speed is directly related to the number and size of objects on-screen. AGS imposes a limit of 15 objects per room, but even if you use all of these and have them visible at the same time, the game speed could suffer.

Right, now back to the pressing matter at hand - letting the player pick up the key.

Inventory

Now wait, there's one more step we need to do first. At the moment we could let the player pick up the key, but then what would happen to it? Where would it go? We need to define the player's inventory.

Click on the "Inventory Items" mode in the left-hand tree. You will see that there are already two items defined - "Key" and "Pink poster". These are just defaults to help you get started. Select "1: Key" in the list. You should see the key image appear on the right. But that's a bit small for an inventory item, I'm sure I saw something better in the sprite list earlier.

Click the "Change image" button below the key, and the sprite manager re-appears. Find sprite number 5, and you should see that it's a much larger picture of a key. Let's use that as our inventory icon. Double-click the sprite to select it.

Yay, we've got a big inventory icon for the key

Ok, there are a few other settings on this screen, but let's return to our objective - letting the player pick up the key. Note that the inventory item number of the key here is 1, as we will need it later.

Back to the interactions

Go back to the Objects pane of the Room Editor, and click on, yes you've guessed it, the Interaction button. We see our old friend, the Interaction Editor, once again. The events here are very similar to the ones we had for the hotspot.

Notice there are two possibilities - "Interact object" and "Pick up object". We actually want to use the "Interact object" event, because we are using the default Sierra-style interface which doesn't have a specific Pick Up mode. The "Pick up", "Usermode1" and "Usermode2" events are useful if you go for a lucasarts-style interface which has more verb types available to the player.

So, double-click on "Interact object". Now, when the player picks it up we want two things to happen - firstly, the object on-screen needs to disappear, and secondly, the inventory item needs to be added to the player's inventory.

See if you can guess which commands we'll need from the listbox. As a clue, we are removing object number 0 from the room, and adding inventory item number 1 to the player's inventory.

Remember, to add more than one command to an event, right-click the event and choose "New action...".

Ok, well here's my solution. As an added bonus, I've also given the player 5 points for their trouble, but you don't need to have that third command:

I've added the two commands we need (and one we don't)

Note that our solution is not perfect - the player can click the hand icon on the key from anywhere in the room and it will disappear. We are also not displaying a message informing the player of what happened. But, the functionality is there, and this will do fine for now.

Okey, so we now have a fully-working first room. Save and test the game as before, and try it out. Once the player has taken the key, call up his inventory and you should see the large key picture there.

Roger stands contemplating the key

Room Settings

Finally, let's just quickly go over the available settings on the Settings pane:

Play music on room load - if set, you can type a music number in the box and that background music will start playing when the player enters the room. For more about music and sound, see later in the manual.
Save/load disabled - if checked, then if the player tries to save or load the game while in this room, global message 983 ("Sorry, not now") is displayed instead. Global messages are described later.
Hide player character - if checked, the player character will not be visible in this room, and the Walk mode will be disabled. Useful for close-up displays of control panels and so forth.
Player character view - you can type a number in here to override the player character's graphic for this room. For example, if you have an overhead map screen, you will probably want a different image of the character from an overhead perspective.
Music volume adjustment - this allows you to modify the background music volume for this screen.

Go to part 5: Global messages and Inventory