Grabbing the screen without Bitmap.snap?

[Firgof]

Working on a game that I'd like to do a 'screen ghosting' effect/glitch, where I take a snap of the present scene (aka 'taking a screenshot'), lower the snap's alpha, and place it at a random small amount of offset for a short period of time before I destroy it.  Unfortunately, Bitmap.snap is incredibly heavily burdensome (135ms!!!) and so it just can't work for real-time purposes.


You can see the effect in motion in RPG Maker VXA here:










Is there any way to ask PIXI.JS for its last rendered screen, or a faster method to grab the screen -- really, anything that would allow me to accomplish the above?  I've considered doing a shader - but I know nothing about shaders or how to implement them in RPG Maker MV.


Any and all suggestions are welcome.

 

[Tsukihime]

When I run Bitmap.snap, the first time it takes 100+ ms, but then after that it takes on average 40 ms.


The speed of the computer probably makes a difference though, as well as the size of the canvas.


I don't know any faster ways of grabbing what's rendered on the stage though.

 

[Firgof]

I'm willing to do things like just read straight from the video card buffer [thus making the game desktop only] if that's what it takes.


As aforementioned in my post, a shader would probably do what I'm asking for here a lot faster - but I don't know how to implement a shader that would accomplish the above effect.