need help with alpha channels

[morboz]

hi everyone
im kinda new to this software, so far im loving it
had some trouble adjusting to the way of thinking when working with it, but i overcame those issues thanks to some common sense and the very helpful information found around this forum.
now, this time i just cant seem to solve this on my own and i couldnt find an answer around here
i need to create an alpha channel for a sequence of animation, my goal is to make a part of the frame transparent
it can easily be done for one frame in a number of ways (erasing it manually for instance) , but it gets tricky when attempting to apply this to the whole sequence
i hope im being clear enough here, in any case everything regarding alpha channels is unclear to me in tvpaint, creating them and using them in a project, using one layer as a mask for another and so on...
for starters id be glad to get some help on this little conundrum, and later it would also be nice to have some input on tvpaint way with alpha channels in general
thanks in advance.

[ZigOtto]

hi Morboz and welcome !

... it can easily be done for one frame in a number of ways (erasing it manually for instance) , but it gets tricky when attempting to apply this to the whole sequence ...

not that tricky,
proceed as you said on one frame, hit "Undo" select your sequence, and hit "Enter", il will process the whole sequence instead of a single frame.

[morboz]

hi ZigOtto and thanks
well, indeed it works, and its true that its simple, but where did it came from?
i would have never guessed anything close to this, care to explain whats the logic behind this operation?
what does 'Enter" do anyway? simply runs the last action on all selected frames? if so can it be used for other things aswell?
sorry for being so inquisitive, but it just amazes me how different this software is from everything else i have worked with.
and since alpha channel is still something i want to get my head around, it would be nice if someone can elaborate on that matter or refer me to some source of information.
thanks

[ZigOtto]

... what does 'Enter" do anyway?

Enter does "Re-Apply" (the last action).

I don't use Alpha so much, and when I do, it's from specific animlayer used as animated stencil (or inverted stencil),
apart that, what I use the more is the "Preserve Transparency" (or lock alpha) button, to paint over something already painted.

[Paul Fierlinger]

i would have never guessed anything close to this, care to explain whats the logic behind this operation?

If you do an operation such as this one on one frame, then undo it, select all frames, and redo it again, you are fooling TVP into just redoing what you had undone but it doesn't know the difference between one or more frames -- kind of like a dog.

[morboz]

when I do, it's from specific animlayer used as animated stencil (or inverted stencil),

as in you use a certain layer as a mask to paint on (inside,outside)?
anyway, the next time ill encounter a problem that this undo/redo trick cant solve ill be back with more specific questions

it doesn't know the difference between one or more frames -- kind of like a dog.

hi paul, its an honor! i see that dogs are not only a passion of yours you put into your movies, but also a philosophy on the mechanics of tvpaint