background_add(fname, removeback, smooth);
|fname||The name (string) of the file to added.|
|removeback||Indicates whether to make all pixels with the selected colour (left-bottom pixel) transparent.|
|smooth||Indicates whether to smooth the edges if transparent.|
With this function you can add an image as a background, loading
it from an external source where the image file to be loaded should
always be *.png format. The function returns the
new background index which must then be used in all further codes
that relate to this background. If you use this function with HTML5
or are getting an image from an URL, this function will also
generate an asynchronous event. See
Advanced Use - More About Async Events for more
Setting the "removeback" argument to true will remove a colour from the background, by checking the bottom left pixel of the defined area for the colour there and then using that as the colour to be removed.
If you choose the "removeback" option, you may also want GameMaker: Studio to smooth the edges of the background by setting the "smooth" argument to true. All this does is create a semi-transparent border around the edges of the background after it has had its background removed.
It is worth noting that when you load a background into GameMaker: Studio in this way you must remember to remove it again (with background_delete) when no longer needed, otherwise there is risk of a memory leak which will slow down and eventually crash your game.
NOTE: Depending on the target platform that is chosen you are limited as to where you can save and load files from. See Reference - Files for more information.
NOTE: You should be aware that if you are using this function in your HTML5 target game to load resources from an external server, then, due to XSS protection in browsers, attempts to load resources from across domains can be blocked and may appear to return blank results.
bck = background_add("Sky_5.png");
The above code loads a background into the game and stores its index in the variable "bck".