Hey guys, Is this preventable? I tried Selecting the canvas with ctrl+A and paint but the brush smudges beyond that. Any ideas?

No, it is not possible to prevent.

At best you could try to go image->trim layers to image size to get the outside bits gone, or use the crop tool, but not sure if that it what you were looking for...

It seems smudge brushes don't take selections into consideration when mapping the colors. They seem to sample colors even from outside the current selection. And if I make the selection in a new layer, it still samples colors from outside the selection from the layer below it. Is that an intended behavior?

That's actually a feature of a handful of smudge brushes. You can turn it off via f5->overlay. Do note that unless you have the opacity locked, all smudge brushes will try to shift around opacity too.

TheraHedwig wrote:That's actually a feature of a handful of smudge brushes. You can turn it off via f5->overlay. Do note that unless you have the opacity locked, all smudge brushes will try to shift around opacity too.

I was aware of the overlay setting in the brush settings and I had that checked off for all my smudge brushes. I was under the impression that checking it on would make the brush sample colors from all layers, but it seems like it's opposite. I just checked it on for the brushes and now they don't sample colors from any other layer other than the current layer. But for the selections, the brush samples the colors from outside of the boundaries, but from the same layer where the selection is made, not from other layers. And when I select all with ctrl + A, now the brushes don't sample colors from outside the canvas too, with overlay turned on.

Uuuuh... That's not supossed to happen. (It is supossed to be like you say, the opposite) Can you tell me which version of Krita you are using and which OS? Because I cannot reproduce that behaviour here on Ubuntu 16.04 with a compiled version of krita...

I'm using 3.0 as well as 3.01 alpha, alongside 2.9.11 repository version of krita, OS- PCLinuxOS. And I tested all of it again, and I think there is something more here. That opacity shift you mentioned, seems like it gets activated when overlay is turned off and deactivated when overlay is on. When the overlay is on, opacity shift doesn't happen , only color mixing happen. I checked it closely, it seems like krita chooses to blend colors two different ways based on the overlay on and off. When off, only opacity shift occur, allowing the colors below show through causing the blending. But when the layers below are turned off, it shows that color weren't mixed, but rather opacity shift was causing that illusion of mixing. But when overlay is on, the colors actually mix! When I turned off the layers below, the paint strokes showed the colors from the current layer, and the layer below mixed. And with overlay on, the brushes respect the boundaries of selections too, by not letting the colors inside or outside the selection mix. But when overlay is off, the opacity shift happens and it doesn't consider the boundaries of selection, making edges transparent with each strokes, which was causing me to think the brush is sampling colors from layers below, or outside the selection. I'm not sure if I'm understanding this right though.

Yes, no, that makes sense. Opacity-shift should also not happen if you have opacity/alpha lock on on a layer (that's done by clickin the checkerbox in the docker)

We've considered getting the opacity shiftnot to happen, but it is super tricky programming wise.

Yeah, I tried alpha locking the layer too. Seems like it works well with selections. Thanks for that opacity shift info too. I had no idea about that. Smudge brushes are probably my most used brushes, so this was a slight annoyance i was facing while working with selections and around the edges of the canvas. Anyway, good to know the workaround.