Blurry and Double-Vision Effects

Lake

How might I go about accessing (and storing, if necessary) previous frames of the screen buffer? I'd like to be able to use them to draw blur effects, double vision effects, trail effects, and so on.

Megalomaniak

Should be able to use a viewport texture for this.

Lake

So, I got this working by rendering my game to my own viewport, than putting a script in my viewport container to save a copy of the drawn texture. So far, that's my best solution, but I'd prefer not to be using up the pointless resources of a redundant viewport (and making them play nice given resizing, etc).

I'd really like to just be able to copy the root viewport's frame, but because it has no parent in the root hierarchy, it'll always be already clear by the time my own node scripts are running. Unless... Can I attach my own script to the tree like any other node? Or is there another way I haven't considered?

Megalomaniak

Honestly, other engines might hide it away perhaps, but they effectively do the same. A viewport in godot is a glorified renderTarget and if you want to do screen space effects you'll need one as a buffer no matter what, in all engines.

As for using the root viewport, not sure but to my mind since it logically is the final output buffer, probably not.

SIsilicon28

Probably not a good idea to use the root viewport for the effect, since that same viewport will also have gui elements rendered to it as well.

Lake

Ah, I'd forgotten about the GUI - although I can think of situations where I might want to do the kinds of effects I'm thinking of there, too... How expensive is drawing to a bunch of different render targets anyway?

SIsilicon28

Depends on what you're drawing to it. If you render your entire scene in one viewport, due some postprocessing, then render that result to the root viewport, along with GUI, then the cost would be the scene + postprocessing + gui.

Also, the larger your viewports the more expensive they are; both memory and processing wise.