====== How to Make Scene Auto-scrolling In Wintermute Engine ======

**__BIG THANKS__** to [[http://forum.dead-code.org/index.php?action=profile;u=9548|anarchist]] for his kind advice and knowledge in scripting! 

It is pretty common for adventure games that a scene auto-scrolls to a given point independently from actor. This scripted event can be easily achieved in WME.

Suppose, you have a scene background that exceeds the scene width. Whenever actor walks around the scene, it scrolls smoothly – you can see that in WME demo project. However you wish your scene could scroll to a given point automatically, without actor’s movement. As if a camera slid past actor to something you wanted to attract players’ attention.

**Note:** It is assumed in this tutorial that you have successfully covered [[http://docs.dead-code.org/wme/inside_scenes_step1.html]] and that the floor region in your scene is extended to the whole (even though actor isn’t going to walk during scene auto-scrolling, it is necessary for WME to “know” that the point that you want your scene to scroll is located within the walkable space). 

===== Step 1 =====

 Open **scene_init.script** and add the following piece of code wherever you want scene auto-scrolling to happen:

<code script>
Scene.AutoScroll = true; //The scene can scroll automatically.
Scene.ScrollTo(); //Scroll the scene to a given point (X, Y) or another actor (sally).
</code>

Test your scene now. Nothing happens and the scene does not scroll anywhere. What is wrong?

Now if you open **game.script** you will find this line there:

<code script>
Game.MainObject = actor;
</code>

It is written in WME Documentation online that 

   Scene.Autoscroll: Specifies whether scene automatically scrolls to the Game.MainObject.

So it makes sense that, when you set **Game.Autoscroll** to **true** the scene scrolls toward the main actor. Also the Documentation says:

   MainObject: The object which is used for the scene's auto-scrolling can be (set to) null.

Since **Game.MainObject** in your game is actor, WME cannot scroll the scene to the point you want, unless **Game.MainObject** is set to **null**. Let’s correct this. 

===== Step 2 =====
 
Add a new line to your code: 

<code script>
Game.MainObject = null; 
Scene.AutoScroll = true; //The scene can scroll automatically.
Scene.ScrollTo(); //Scroll the scene to a given point (X, Y) or another actor (sally).
</code>

Come on, test the scene now. That’s it – it is auto-scrolling smoothly to the point that you wanted!

===== Step 3 =====

And after you have done the scrolling add these two lines:

<code script>
Scene.AutoScroll = false; //The scene cannot auto-scroll.
Game.MainObject = actor; //Actor is MainObject again.
</code>

This way actor “gains control” over the scene (or whole game) again.

But what if you wanted to change the speed of auto-scrolling? What if it seems too slow or too fast? 

**ScrollSpeed** is an attribute of the Scene object. As it is said in the Documentation [[http://docs.dead-code.org/wme/generated/scripting_ref_scene.html]]:

   ScrollSpeedX: Horizontal scrolling speed (in milliseconds, default=10)
   ScrollSpeedY: Vertical scrolling speed (in milliseconds, default=10)
   ScrollPixelsX: Horizontal scrolling shift (in pixels, default=1)
   ScrollPixelsY: Vertical scrolling shift (in pixels, default=1)
   OffsetX: Current horizontal scrolling offset of the scene
   OffsetY: Current vertical scrolling offset of the scene.

As you can see, you can choose between horizontal (X) and vertical (Y) scrolling speed.

By default **ScrollSpeed** is set to 10, so you need to specify another integer if you want to change scrolling speed. 

===== Step 4 (optional) =====

Write in this line right before **Scene.ScrollTo():**

<code script>
Scene.ScrollSpeedX = 2; //Default is 10, so this will make the scene scroll faster horizontally (along X coordinate).
</code>

If your wish is to slow things down, replace “2” from our example to “20” or any other integer. 

Then run the game and enjoy.