Game Maker

Backgrounds

thanks to:

margaret.meijers@education.tas.gov.au. This page was last modified on Sunday, 27 May 2007. The URL for this page is http://www.mindtools.tased.edu.au/gamemaker/tutorials/tiledbackgrounds.htm .
This work is licensed under a Creative Commons Licence.
Some pages of this site have been developed with support from the SiMERR Project.

If you want a nice looking background you can create lots of objects and build your rooms from these objects.  This however takes a lot of work and makes your game slow because of the large number of objects. 

The best way to make good looking backgrounds is to use tiles.  Tiles are bits and pieces of an image that can be placed in different places on the background.  Memory usage is much less, and as tiles are not game objects and don't have collision checking your game will run much faster.

First you need to get a suitable tile set to use.  You can download some from the resources section of the official Game Maker site at http://www.gamemaker.nl/resource.html

I will be using this one from the Game Maker site:

 

Start with a new empty room

Add a background and name it bgrTiles.  Load one of the tiled images you downloaded.

Click the 'Use as Tileset' option:

You then need to adjust the Tile Properties (width, height etc) until the grid lines match those on the image.

Add another regular background, such as sky.gif to go behind your tiled picture.

Now go to your room, select the tiles tab.  Click on a tile, then click to place it in your room.  Build your world.

Now go to the backgrounds tab, choose the sky background.

Untick the Draw background colour option.

  This causes a problem though.  How does your game know when something has collided with a object that is just part of the background picture? The secret is to place plain wall objects wherever there are walls (exactly the same size and in the same place as the background pictures) but make the plain objects invisible.  When you play the game you don't see the plain invisible wall objects, you see the attractive background.
Create a new sprite sprPlatform that is just a square block of colour the same size as your grid.  Untick transparent.

Create an object objPlatform and attach the sprite to it.  Untick Visible.

Place the objPlatform blocks on top of your tiled image platforms.  Don't worry that your platforms seem to be hidden.  The objPlatform blocks are invisible, so you won't see them when you try the game, but you can collide with them. 
 
By using tiled backgrounds, you can make a platform game with only one platform object, but it looks like the player is walking along all sorts of different things, such as fences, castles, grass, water etc.    
You can create blocks smaller than your grid size to get more accurate positioning for your characters when they land. Create half size blocks: a 16x8 block and call it objPlatform_horiz and an 8x16 block called objPlatform_vert

Make the objPlatform block the parent block for each of these.  That way they will inherit the same behaviours, so you do not need to set events for them.

Now you can place them where only half a grid square is covered by the background.  eg for the end of clouds etc.