First step for GSoC: the Painterly Color Mixer.

[Emanuele Tamponi]

Bart Coppens ha scritto:
>>     The mixer takes the footprint of the paintop. Then the
>>     footprint is mixed with the underlying colors. Optionally, the
>>     result is automatically set as the current color of the
>>     paintop.
>>     
> Ok, but how will you introduce new colors on the mixer? Like you write a bit 
> later on: you want to set the color of the dab to 'white'. That way, no new 
> colors will ever be introduced onto the mixer except white. So if you start 
> with a white mixer, it'll never get anything else.
> So I think you should also allow the current paintop color to be transfered to 
> the mixer, instead of only allowing the transfer of the color from the mixer 
> to the paintop. In essence, you want a bidi approach here, I think :-)
>   
I set the color of the dab to white (or, well, transparent). Then I draw 
the footprint
on the dab: now the dab is no more white, it has the color drawn by the 
paintop :)
Is it clear now?
>>     To do this, we need to know the nature of the current paintop:
>>     we expect that a pencil mixes colors in a different way
>>     respect a brush; and this just because the brush is wetter
>>     than the pencil.
>>     
> Yep, that is indeed a hard problem.
>
>   
>>     But current brush and pencil paintops (to make an example)
>>     don't have any painterly properties, so the mixer doesn't know
>>     about their wetness. On the other hand, there will be some
>>     paintops that do have painterly properties.
>>     
> Indeed.
>
>   
>>     My idea is: for all non-painterly paintops, the mixer guesses
>>     about their wetness using their ids. For painterly paintops,
>>     the mixer takes their properties using KisPaintOpSettings.
>>     
> *cringe* This sounds very bad. 'Guessing' is always a bad thing if computers 
> are involved :-) If you really need this information, you might want to 
> introduce a new derivative class of KoColorspace or so called 
> KoPainterlyColorspace. Then you can try to dynamic_cast into it, to see if 
> the paintop can do cool wetness stuff, and then put some wetness info in that 
> class, so you can use it.
>   
Your idea is just an implementation of what I called "guessing"... Since 
that class
will contain guessed stuff for non-painterly paintops :)
>>     First issue: we don't want to respect exactly current paintop
>>     settings: for example, it's better if we use a different size
>>     for the paintop, and, if the current dab of the paintop is a
>>     pattern, we will ignore it (we mix colors, not peppers! ;) and
>>     take a default color instead.
>>     
> I agree on the pattern, I don't on the paintop size. That you don't want to 
> see a pattern being drawn sounds OK, since they don't have wetness 
> information and so ;-). On the other hand, the user might want to choose a 
> huge brush size to make a huge dab of 'base mix color', and then use a 
> smaller brush to finetune different parts of it. At least, that's how I 
> imagine how I'd use it, but I'm not a real artist :-)
>   
This is an interesting point. But in Corel Painter X, the brush size in 
the mixer
can be different from the "main"/"real" one. You just need to "magnify" 
the result...
>   
>>     Another issue: the bidirectional paintop that I'm going to
>>     implement will interfere with the behavior of the mixer. In my
>>     opinion, his "bidirectionality" (excuse me for the term :) has
>>     to be deactivated while you use it in the mixer.
>>     
> Well, I think I would expect a bidi behaviour in the mixer, so I'm not sure 
> about this.
>   
Now perhaps you understand this point: the bidirectional paintop does 
more or
less the same thing that the mixer does.
You say: "so let use the mixer only with the bidirectional paintop"
I say: "let the mixer work with *any* paintop, and deactivate the 
duplicate behavior
of the bidirectional paintop".
Got it? What do you think?
>>     To do all this, my idea is:
>>     - Draw the paintop footprint in a white dab (this way, the
>>       bidirectional paintop can't do its stuff).
>> [...]
>>     - Mix up the color on the dab with the color in the mixer
>>       canvas.
>>     
> This confuses me even more. Which is why I think I misunderstand =)
>
>   
Again, I hope you understand now :)
> Monday or Tuesday is so fast :D Even if it is not what I think would work, a 
> prototype of this would be interesting to see in action anyway, might 
> convince me that it's actually a good thing to have. Cool.
>   
Too fast? We'll see ;)

Emanuele