Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread David Gowers
On Mon, Apr 27, 2009 at 4:42 AM, Rob Antonishen
 wrote:
> Here is another question... Should the basic paint calls (I.e. Those
> with the description "using current brush") that have no parameters
> just be changed to paint respecting all the current brush options,
> like scaling, jitter, etc. ?

We cannot do that, unfortunately, as it would substantially change the
meaning and effect of some existing scripts and plug-ins.

David
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Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread Rob Antonishen
So is your thought to provide a new set of PDB calls with extra
parameters like brush scale, jitter, etc?  The drawback to this might
be that as more brush dynamics get added the functions will get
obsoleted, much the current set that provide gradient colouring.

Here is another question... Should the basic paint calls (I.e. Those
with the description "using current brush") that have no parameters
just be changed to paint respecting all the current brush options,
like scaling, jitter, etc. ?

-Rob A>

On 4/26/09, LightningIsMyName  wrote:
> Hello,
>
> On Sun, Apr 26, 2009 at 1:43 PM, David Gowers <00a...@gmail.com> wrote:
>
>>> I'm willing to try to write a patch to add this for gimp-paintbrush,
>>> gimp-airbrush, etc.
>> Do you understand that you must not change the api of gimp-paintbrush,
>> gimp-airbrush, etc? Because that would break a lot of scripts and
>> plugins. This is part of the problem with the current PDB interface to
>> tools; supporting new options must be done through additional PDB
>> functions.
>>
>> David
>>
>
> I understand that, we obviously mustn't change the old API. What I
> meant was to create something like gimp-paintbrush-wtih-dynamics.
>
> The question is, when and how do we want to do this? Do we want to
> give some sort of option now, and we will replace it when we move to
> GEGL painting, or should we wait? I would like to see it implemented
> before 2.8 if possible, however If we need to wait with this, i'll
> wait.
>
> ~LightningIsMyName
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Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread LightningIsMyName
Hello,

On Sun, Apr 26, 2009 at 1:43 PM, David Gowers <00a...@gmail.com> wrote:

>> I'm willing to try to write a patch to add this for gimp-paintbrush,
>> gimp-airbrush, etc.
> Do you understand that you must not change the api of gimp-paintbrush,
> gimp-airbrush, etc? Because that would break a lot of scripts and
> plugins. This is part of the problem with the current PDB interface to
> tools; supporting new options must be done through additional PDB
> functions.
>
> David
>

I understand that, we obviously mustn't change the old API. What I
meant was to create something like gimp-paintbrush-wtih-dynamics.

The question is, when and how do we want to do this? Do we want to
give some sort of option now, and we will replace it when we move to
GEGL painting, or should we wait? I would like to see it implemented
before 2.8 if possible, however If we need to wait with this, i'll
wait.

~LightningIsMyName
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Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread David Gowers
Hi Theodore,

On Sun, Apr 26, 2009 at 8:00 PM, Theodore Imre  wrote:
> gimp is not a good choise for digital painting because it doesnt have a
> blending tool. Paint tool sai in the respect is far superior because its
> brush engine is much more advanced for smooth blending
Please keep your replies on topic.

This thread is about improving the plugin API to the painting system
of GIMP (which is not, anyway, a program for digital painting, but a
'Image Manipulation Program'; naturally tools designed for digital
painting, Like MyPaint or Krita, will be better for digital painting.)

As Paint Tool Sai is also not open-source, it definitely has no
relevance to this thread, unless it also possesses a programming API
for plugins or scripts to non-interactively paint which solves this
same problem, and which you will describe.

David
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Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread David Gowers
Hi LIMN,

On Sun, Apr 26, 2009 at 7:07 PM, LightningIsMyName
 wrote:
> Hello,
>
> Gimp 2.6 allows to use brush dynamics to control opacity, size, hard and 
> color.
> These features greatly increase the drawing capabilities of gimp, and many
> users find them very useful.
> However, we don't have any way to access these from inside the PDB...
>
> I think that it would be nice to be able to access these using the PDB, 
> however
> I'm not sure about the right method:
> Do we want to allow the user to specify velocity, and pressure for each coord,
> or should we use the "emulate brush dynamics" feature (the same one we have in
> the libart stroking)? Personally, I believe that the "emulate brush dynamics"
> is the right method.

We should definitely make dynamics available, but IMO both of these
methods is quite unsuitable and would only add to the current
inconsistencies of the pdb interface to paint tools.

In my opinion this is what needs to happen:
 A) Migrate paint tools at least partially to GEGL (so that the actual
rendering of strokes is done by evaluating a 1-node GEGL graph). This
will help us define a consistent, expansion-compatible way of
communicating and storing stroke information.
 B) Make a system for handling both full strokes (where each point
specifies parameters such as brush scale, rotation, aspect ratio,
spacing directly) and simple strokes (where each point only specifies
the 'source' information -- pressure, velocity, angle, etc.), and
converting simple to full strokes
 C) Work out a way to pass this information through the PDB, in a
backwards + forwards-compatible way
  -- so that older scripts work in newer versions because their
missing fields are automatically expanded and filled in with sensible
default values, and that newer scripts work (in a limited sense) in
older versions of GIMP.
 D) Provide a method of constructing and communicating GEGL graphs
through the PDB.
  This can be used by scripts to actually do the required painting.
 E) Use it (and deprecate the current 'gimp-paintbrush' etc API)

I also think we need to look harder at our current inability to
communicate various tool options such as Jitter,  Color from Gradient,
 and Incremental; possibly communicate these via a keyword-argument
sort of interface (ala Python)

>
> I'm willing to try to write a patch to add this for gimp-paintbrush,
> gimp-airbrush, etc.
Do you understand that you must not change the api of gimp-paintbrush,
gimp-airbrush, etc? Because that would break a lot of scripts and
plugins. This is part of the problem with the current PDB interface to
tools; supporting new options must be done through additional PDB
functions.

David
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Re: [Gimp-developer] Should we add the option to use brush dynamics from the PDB?

2009-04-26 Thread Theodore Imre
gimp is not a good choise for digital painting because it doesnt have a
blending tool. Paint tool sai in the respect is far superior because its
brush engine is much more advanced for smooth blending

On Sun, Apr 26, 2009 at 11:37 AM, LightningIsMyName <
lightningismyn...@gmail.com> wrote:

> Hello,
>
> Gimp 2.6 allows to use brush dynamics to control opacity, size, hard and
> color.
> These features greatly increase the drawing capabilities of gimp, and many
> users find them very useful.
> However, we don't have any way to access these from inside the PDB...
>
> I think that it would be nice to be able to access these using the PDB,
> however
> I'm not sure about the right method:
> Do we want to allow the user to specify velocity, and pressure for each
> coord,
> or should we use the "emulate brush dynamics" feature (the same one we have
> in
> the libart stroking)? Personally, I believe that the "emulate brush
> dynamics"
> is the right method.
>
> I'm willing to try to write a patch to add this for gimp-paintbrush,
> gimp-airbrush, etc.
>
> ~LightningIsMyName
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>
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