Re: [Gimp-developer] Shape layers for GIMP?

[Jeremy Morton <admin game-point net>]

Yes, processors nowadays are very powerful and indeed applying a bunch 
of effects onto a shape layer every time you make a change takes a good 
amount of CPU power; but that's fundamentally different, because at 
least there, there is a finite limit of the number of operations that 
will need to be reapplied per change (ie. every single layer effect is 
turned on, the CPU will have to re-apply every single layer effect). 
However, the idea of being able to modify any change in the undo buffer 
is much more difficult, because there is a potentially infinite number 
of past changes.  I could design a really complex shape, apply 100 
effects, then go away and do loads more complex work with loads more 
complex effects, then design another really complex shape, etc.  By the 
time I want to go back 1000 (by the way, actually finding the edit I 
want to modify would be rather difficult at this point too!), the CPU 
has to apply 1000 processor-intensive effects.  That's WAY more work 
than even the worst-case scenario with something like a shape layer. 
But it just gets worse and worse.  What will the performance be like if 
I want to modify something 10,000 moves back?  100,000?  At some point 
this idea because unfeasible, it seems to me.  Modern CPUs can perform 
"quite a lot of operations without cumbersome delay", but even the most 
powerful CPU is going to start to hurt at some point, and in advanced 
graphics editing, that point may arrive rather quickly.

> operations without cumbersome delay. And, clearly: if many slow
> filters have to be recalculated
> in order to update the screen, the user may have to wait. But again,
> what would be the better
> alternative -- simply not allow to re-adjust that operation from long
> ago?

Yes.  Or to give the user a warning that this operation is likely to 
take a long time.  But because it may be likely to take a long time, it 
is no replacement for shape layers.  The great thing about shape layers 
in Photoshop is that you get a "live preview" - it is able to render the 
layer effects almost immediately every time you make a change.  It 
wouldn't be worth it if you had to wait 10 seconds every time.

--
Best regards,
Jeremy Morton (Jez)

On 09/09/2012 20:10, yahvuu wrote:
> Hi Jeremy,
>
> Am 09.09.2012 13:32, schrieb Jeremy Morton:
> > On 09/09/2012 12:24, yahvuu wrote:
> > > My understanding is that you will be able to go back in the operations history and just modify the path.
> > > All consequences of this modification will be displayed live. No need to declare special "layer effects"
> > > or special "shape layers".
> >
> > Well that sounds great, but I don't really see how it's feasible.  What if you want to modify an operation 1000 complex edits ago?  The CPU is going to have to redo those 1000 edits every time you modify; surely this would become cumbersome very quickly?
> what gets better if you redo those 1000 complex edits manually?
>
> Your shape layer example probably shows that current computers can perform quite a lot of
> operations without cumbersome delay. And, clearly: if many slow filters have to be recalculated
> in order to update the screen, the user may have to wait. But again, what would be the better
> alternative -- simply not allow to re-adjust that operation from long ago?
>
> There is a wide range of possible optimizations, so it is probably better to think of
> non-destructive editing not as a macro-recorder which has to replay any stroke and user action
> in strictly the same way, but rather as building a list of operations that achieves the desired effect
> in the shortest way possible.
>
>
> best regards,
> yahvuu