Hi,

On Thu, 2007-07-19 at 19:40 +0200, Jürgen Hubert wrote:

Especially interesting is its tilt sensitivity. However, the only tool tilt sensitivity seems to have an effect on is the Ink tool. Is this accurate or am I missing something?

That is mostly accurate. In theory one could also create a brush pipe that reacts to tilt but I am not sure if this really works. As far as I know no one has tried this yet and it would be very tedious, to say the least.

Furthermore, I've noticed that you apparently can't use the "Undo" function for the Ink tool. Is there a specific reason for this?

If Undo doesn't work, that would be a bug. But it seems to work fine for me.

Sven

Hi,

On Thu, 2007-07-19 at 22:08 +0200, Jürgen Hubert wrote:

I tested it again, and it seems that this only happens when I use the Ink tool with the Intuos (1) tablet (whether I use the pen tool or the Intuos mouse) - when I use my regular mouse instead, I can use the Undo function.

That is very strange as it shouldn't make any difference. Have you had a look at the Undo dialog?

Sven

On 7/19/07, Sven Neumann wrote:

Hi,

On Thu, 2007-07-19 at 19:40 +0200, Jürgen Hubert wrote:

Especially interesting is its tilt sensitivity. However, the only tool

tilt

sensitivity seems to have an effect on is the Ink tool. Is this

accurate or

am I missing something?

That is mostly accurate. In theory one could also create a brush pipe that reacts to tilt but I am not sure if this really works. As far as I know no one has tried this yet and it would be very tedious, to say the least.

I have personally tried to create such a brush, but the results are inconclusive. I use an Intuos 3 tablet and have created (just for test) a 3 x 3 matrix containing 9 images and 2 ranks, first for x-tilt and second for y-tilt. As far as I understood, this would have created one image for: negative X tilt, negative Y tilt
no X tilt, negative Y tilt
positive X tilt, negative Y tilt
negative X tilt, no Y tilt
no X tilt, no Y tilt
positive X tilt, no Y tilt
negative X tilt, positive Y tilt
no X tilt, positive Y tilt
positive X tilt, positive Y tilt

I was not able to consistently paint with the images corresponding to the tilt I was using then (i.e. had my stylus inclined top left, which I considered negative X tilt, negative Y tilt) in order to paint with the image from cell 1. Sometimes it worked, sometimes it used one of the images 7, 8 or 9, sometimes it used image 3.

I suspect the code is bugged, but I gave up on that idea and would not want to submit a bug report that is not thoroughly tested (I know most developers love to discard those :) )

Sven Neumann (sven@gimp.org) wrote:

On Thu, 2007-07-19 at 19:40 +0200, Jürgen Hubert wrote:

Especially interesting is its tilt sensitivity. However, the only tool tilt sensitivity seems to have an effect on is the Ink tool. Is this accurate or am I missing something?

That is mostly accurate. In theory one could also create a brush pipe that reacts to tilt but I am not sure if this really works. As far as I know no one has tried this yet and it would be very tedious, to say the least.

The "Felt Pen" brush is tilt-sensitive.

Bye, Simon

Hi,
acgaber@gmail.com (2007-07-19 at 1856.54 -0400):

I have personally tried to create such a brush, but the results are inconclusive. I use an Intuos 3 tablet and have created (just for test) a 3
x 3 matrix containing 9 images and 2 ranks, first for x-tilt and second for
y-tilt. As far as I understood, this would have created one image for:

[...]

I did a demo for some "doubts" in IRC, over two years ago, and I barely remember it so excuse the fuzzyness of the description (currently I do not have access to the tablet, so no way to test it again): 3*3 items per layer were for tilt, using each axis as indexer, and the layers were another indexer or two (2 groups of 2 layers), thus giving 3D or 4D "image". I think it worked at the time, allowing people to see the effects of the 3 or 4 tablet variables.

http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-angle-and-tilts.gih http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-angle-and-tilts.xcf.bz2 http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-pressure-angle-and-tilts.gih http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-pressure-angle-and-tilts.xcf.bz2

GSR

Hi GSR,

Thank you very much for your examples, they also helped me understand a bit more the "Save as GIH" dialogue. One of the things that strikes me as illogical was that you start the ranks from the bottom and go to the top as you add more ranks?... It seemed more logical to me to have the first governing rank on top, while the second is underneath it, etc. If you don't mind explaining the logic, it would be great and might teach me a thing or two about GIMP and this concept.

So, taking your brush "pipe-brush-pressure-angle-and-tilts.gih", I read the first rank for x-tilt, composed of 3 cells. Next rank, y-tilt, created from 3 cells as well - so far, that's a 9 cell matrix with the numbers 1 through 9, printed according to the X/Y tilt. Then you have an angular brush with two ranks (the black and red colored numbers governing the angle of your stroke, somehow the black only appears from degree 0 (upwards) to 90 (right), from 90 to 359 the red takes over? Shouldn't it be black from degrees 0 to 179 and red from 180 to 359?) and the last rank, pressure, uses black and red colors for a light pressure and green and blue for harder pressure, alternating colors as per the angle of your brush.

P.S. I'm "explaining" these things back to you just to make sure I understood things right, please don't feel offended if I state the "obvious" :) But your example is much appreciated, it proved the options work as expected (except that weird angular decision) and also gave me an insight the manual was not able to provide.

On 7/21/07, GSR - FR wrote:

Hi,
acgaber@gmail.com (2007-07-19 at 1856.54 -0400):

I have personally tried to create such a brush, but the results are inconclusive. I use an Intuos 3 tablet and have created (just for test)

a

3
x 3 matrix containing 9 images and 2 ranks, first for x-tilt and second for
y-tilt. As far as I understood, this would have created one image for:

[...]

I did a demo for some "doubts" in IRC, over two years ago, and I barely remember it so excuse the fuzzyness of the description (currently I do not have access to the tablet, so no way to test it again): 3*3 items per layer were for tilt, using each axis as indexer, and the layers were another indexer or two (2 groups of 2 layers), thus giving 3D or 4D "image". I think it worked at the time, allowing people to see the effects of the 3 or 4 tablet variables.

http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-angle-and-tilts.gih

http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-angle-and-tilts.xcf.bz2

http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-pressure-angle-and-tilts.gih

http://www.infernal-iceberg.com/gimp/tmp/pipe-brush-pressure-angle-and-tilts.xcf.bz2

GSR

Hi,
acgaber@gmail.com (2007-07-22 at 1801.32 -0400):

Thank you very much for your examples, they also helped me understand a bit more the "Save as GIH" dialogue. One of the things that strikes me as illogical was that you start the ranks from the bottom and go to the top as you add more ranks?... It seemed more logical to me to have the first governing rank on top, while the second is underneath it, etc. If you don't mind explaining the logic, it would be great and might teach me a thing or two about GIMP and this concept.

Origin of coords does not need "common sense", just that the rules are known and not ignored. Someone decides 0,0 is somewhere, and +X goes this way and +Y this other. That applies both to maths and to this. :] Sadly "known" is not 100% in GIH-land (I remember Gimp 1.2 dialog had controls to the side and even allowed 5 dimensions, even if only 4 controls were provided... what was the 5th?), at best you have to go with empiric conclusions.

So, taking your brush "pipe-brush-pressure-angle-and-tilts.gih", I read the first rank for x-tilt, composed of 3 cells. Next rank, y-tilt, created from 3 cells as well - so far, that's a 9 cell matrix with the numbers 1 through 9, printed according to the X/Y tilt. Then you have an angular brush with two ranks (the black and red colored numbers governing the angle of your stroke, somehow the black only appears from degree 0 (upwards) to 90 (right), from 90 to 359 the red takes over? Shouldn't it be black from degrees 0 to 179 and red from 180 to 359?) and the last rank, pressure, uses
black and red colors for a light pressure and green and blue for harder pressure, alternating colors as per the angle of your brush.

I learnt that looking inside the GIH files was a sure way to get a headache. I always looked at XCF versions, and considered GIH a nasty manual step required to get brushes working, instead of having the XCF as single file that had to be created and tweaked. Or even better, having that and run-time controls to change the mappings (what goes with pressure, etc), so not saving at all except to change "images" or default mappings.

The 3D angle-and-tilts brush works, giving ~90 deg to each of the four layers. But yes, I checked the 4D pressure-angle-and-tilts brush with mouse, and it strangely gives a 90-270 instead of 180-180. I thought (or so my memory says I did), that it would select one of two groups by angle (KR or GB), and then select the exact layer by pressure (if it got to KR, K or R). I am unable to test pressure (or tilt), but if you say it selects two colours for high and the other two for low, that part seems to match what I thought.

When the dialog was to the side, I read it this way, for 4D:

Select Select Select Select group of -> one layer -> cells in -> cell in layers from group Y axis X axis

The example brush has the following:

Pressure -> Angle -> Y tilt -> X tilt

So the path would be, with mouse (fixed pressure, fixed 0 tilt):

KR GB -> K R -> 2 5 8 -> 5 -> Black or red 5s Mouse 0-90 0-deg 0-deg pressure or tilt tilt says 90-360
"1st" (?)
always

Maybe there is a bug, or I set something wrong in the save dialog or some hidden rule escaped my experiments (maybe there is "no layers in groups" after all, go figure).

P.S. I'm "explaining" these things back to you just to make sure I understood things right, please don't feel offended if I state the "obvious"
:) But your example is much appreciated, it proved the options work as expected (except that weird angular decision) and also gave me an insight the manual was not able to provide.

No problem, I remember the issue is far from documented, it seems barely anybody knows how things work or worse, how it should work, so the topic quickly gets discarded. Experimenting without going into the deeper levels is enough for me, even if not being 100% sure the things are correct. This is the third time, at least, years ago first, the IRC session second, and some parts still unclear. Sadly all the manual steps (including for single image brushes) makes the brush system really tedious and clunky, so I understand that as things get more complex they get less use and less understanding.

Good luck trying to figure any misconceptions or missing details. See the issue with 90+270 deg instead of 180+180, and I would add why you can control the cells up to 1000 or why playing with different buttons makes other values change (cell size -> number of cells and count in first rank, but not other ranks). Best would be figuring how it was planned to be.

GSR