On Mon, May 29, 2000 at 02:28:33PM +0200, Raphael Quinet wrote:
> Well, it looks like I will not be able to attend the GIMP Developers
> Conference at the end of this week (too bad - I really wanted to be
> there), so here is an idea that could be discussed: there could be
> an option to rotate a brush automatically according to the local
> tangent of the path that the brush is following.  To make it even
> nicer, the user should be able to specify what is "local": how many
> pixels should be taken into account for calculating the angle.

I was thinking about this yesterday! I think brush spacing is also
important in this case - you would want to be able to stroke with,
say, a rainbow line, and have both edges of the stroke come out
perfectly smoothly, as if you had stroked with a couple dozen parallel
single-pixel brushes.

Brush pressure/alpha/transparency is also important. When you're
stroking a circle, you don't always want the inside of the circle to
be more opaque just because the brushstrokes are somehow "denser"
there. You _do_ want this if you're trying to imitate natural media,

If I recall correctly, DeluxePaint IV on the Amiga (or DeluxePaint
Animation on the PC) and an animbrush auto-gen facility which let you
turn your static brush into an animated brush by rotating it and
storing all the frames. Maybe I did that by hand - I don't remember
now. Anyways, this would end up being a _lot_ of data to have in your
image hose so I agree that rotating the brush automagically to match
the local tangent is a good idea.

[example of walking person snipped]

If you're stroking a circle clockwise and your animated person will be
walking around the outside, then stroking the circle counterclockwise
would make your person walk on the _inside_ of the circle ... so there
should be built-in facilities to mirror/flip the active brush as well.

I think that most basic image transformations should be applicable to
an XCF that is intended to be used as an image hose. For example, if
you have a 15-layer image of a person walking, there should be a
one-step script to make it N times as tall, rotating N steps through
360 degress. That would cut out a lot of tedious rotation.

What other transformations could be added? How about: blur, colour
rotation, scaling...

Oooh, here's an interesting question: what happens when you're using
the smear tool with a brush which gets smaller the faster you go?  Is
the smeared data shrunk along with the brush? That could look really
really cool.

Of course all these transformations should be available on-the-fly,
and it would be nice to be able to load an image hose and then just
"add" another dimension to it - a dynamic version of the image hose
save dialog.

Just my 2/100 of a Euro.


--   Tom Rathborne     [EMAIL PROTECTED]     http://www.aceldama.com/~tomr/
--  "We promise according to our hopes, and perform according to our fears."
--                                     -- Francois, Duc de la Rochefoucauld 

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