[Gimp-developer] What would it take to add an option for the Pencil tool to support brush transparency?

[James Houx <pha3zme gmail com>]

I /really, really /badly want this feature!  Badly enough that I will 
have to figure out how to hack the source myself unless can tell me a 
way to accomplish it.

Basically, the problem is this:

The brush tool uses sub-pixel sampling to get an anti-aliased effect 
when you paint.  I don't want this, because I'm working at pixel-level 
scale and I need exact pixel painting with anti-aliasing.

The pencil tool would be the natural solution, but the pencil tool does 
not support transparency for RGB brushes!  I'm surprised because it 
seems like such a very simple feature. :(

Without this, there's no way to do per-pixel precise painting that 
supports transparency.  Is this something that would be possible to add 
in the current developer release?  Or if nobody has time, could someone 
please tell me where I'd have to look in the code to add support for it?

Fyi, no other paint program out there supports this entirely.  I checked 
Krita, Paint Shop Pro, and Photoshop.  Paint Shop Pro technically does 
do it, but the features of the "Picture Tube" are absolutely horrible in 
their limitations.  GIMP should be able to do it *easily* if the pencil 
tool could just be modified with an option to support transparency from 
the source brush image.

I really desperately need to be able to do this exact technique for a 
game I'm developing that requires a tremendous amount of by-hand, 
per-pixel terrain and vegetation painting.  I would be so greatly 
appreciative if anyone can tell me how to make this technique possible! 
/Thank you in advance!/

James