Separate canvas for background image.

[opd]

Hi,

I'm finishing up my first Pixi project and am thinking about performance.  

I'm using the PIXI.Application class which creates the canvas, renderer, ticker and then updates the canvas every frame.  As I understand it, this means that the whole canvas gets redrawn every frame.

Would it be a good idea to put the background image into a separate canvas below the app, so it doesn't have to be redrawn each time? 

Also, is it best practice to manually handle updating the canvas and to only redraw the parts that change?

[ivan.popelyshev]

For older mobiles - yes.

> is it best practice to manually handle updating the canvas and to only redraw the parts that change?

Only if you have many filters and you know how to use renderTexture to cache those parts. Otherwise, its very bothersome. Also, there's no guarantee that canvas contents are preserved between frames, so trying to update only certain regions will certainly fail in webgl.