GNOME Bugzilla – Bug 50638
Use lookup table for tablet pressure
Last modified: 2010-03-07 16:52:30 UTC
Using a lookup table to filter the pressure information would result in highly customizeable tools together with a graphicstablet. Seems easy to implement to me and the WACOM Windows driver also does it so this is a MUST HAVE. :)
Re-assigning all Gimp bugs to default component owner (Gimp bugs list)
Perhaps instead of a lookup table, we could have a pressure curve somewhat like Painter and gsumi have. That way, each tool can be fully customized and would aid in simulating natural materials with a tablet. Each attribute of a certain tool could have its own curve, resulting in very high levels of customization.
Brett, that is exactly what this bug report is all about. A lookup table is how this would be implemented internally.
We just tried a Wacom Intuos 3 tablet on a fresh install of Gimp (latest 2.2 in Win XP Pro). We get mouse control (move cursor, operate controls, draw etc) with no pressure response. A search on the forums found reference to this with an explanation that under the XP version of GIMP there is no support for Windows' Wintab dll. Is this relevant? We would love to get pressure support as Gimp now looks very real indeed. Cheers Peter Robertson
Comment #4 asks reasonable questions, but it is out of place in this bug report. In fact, it is a request for information rather than a bug report, and should be asked in a forum such as the mailing list gimp-user@lists.xcf.berkeley.edu.
I just saw a demo of Krita 1.6.2 taht includes editable curves for how the pressure information is mapped to brush size, opacity and color. There are 3 separate curves, easily editable by the user (just like our curves tool).
@Raphaël Quinet: http://alexmac.cc/tablet-apps/
Almost the entire infrastructure for this is there now. I'd like to implement that for 2.8.
I think not only pressure but also velocity may need an editable curve in The Gimp. With my Wacom tablet under Windows it's very hard to take advantage of the velocity setting, as maximum effect is achieved only by moving the pen very fast.
The sensitivity for velocity is configurable already in the Brush Dynamics expander in the paint tool options.
The setting works, but not in the way I would expect. It affects how big the maximum effect should be, but not how fast the pen needs to move to achieve it. For example, if I set the velocity setting to have effect on color (the faster the pen moves, the more the stroke color is closer to the foreground color), no matter how the sensitivity is set, to completely reach the same color as the foreground color settings I still need to move the pen very fast. If I set the velocity setting to have effect on brush size, the sensitivity adjusts only how small the size can get as the pen velocity rises. But the pen still needs to be moved very fast to get the maximum effect allowed.
When curves get added for pressure, they will at the same time be added for all other valuators, including velocity. This will happen for 2.8.
*** Bug 572100 has been marked as a duplicate of this bug. ***
reassigning to myself to keep track of this.
Michael has implemented it for pressure, but not for velocity and velocity probably wont make it to 2.8. Dynamics curves will however let one compensate for this limitation.
Let's close this as FIXED then. It's about pressurem which is there now, or actually about compensating for whatever physical tablet properties, and "velocity" is not a direct input value from the tablet, it's derived by GIMP.