I recently got a XP-PEN Artist 15.6 Pro which I am using with the Krita 4.3.0 beta on Linux Mint 19.3. When drawing with it, I am noticing a strange issue when trying to use the tilt, specifically with brushes like the tilt pencil that have their rotation linked to the tilt rotation of the pen. With these settings, I am unable to rotate the brush to be directly horizontal or vertical. The rotation instead “snaps” from one side of horizontal or vertical to the other, which produces discontinuities in my drawing. here is an example of what this looks like with the tilt pencil:
Here is a video of the issue in action. The issue also occurs when using Krita 4.2.9 on Windows 10, as well as with the spray brush in ArtRage 5, also on Windows 10. I’ve been in touch with XP-Pen support and they can reproduce the the issue on ArtRage, so it doesn’t seem like I simply have a defective tablet.
Are there any other Artist 15.6 Pro owners here? Do you experience this issue with the tilt as well? Are there any settings in Krita that could be affecting this?
c) Pencil-5 Tilted uses Tllt direction to control the brush rotation and your video shows you varying tilt direction - ok.
Is there a Tilt elevation output?
What is your stylus output supposed to be?
Using only stylus pressure to control the brush rotation, I get a smooth 0-360 degree variation. This suggests that your tilt-direction output has a limited range and perhaps effectively goes from -X to +X instead of 0 to 2X, which would give you a discontinuity and a snap/flip from one part of the standard transfer curve to the other.
EDIT:Additional: Here is an extract from the XP-Pen Artist 15.6 Pro website where it states that it “supports 60 degrees of tilt function”.
That diagram seems to indicate 60 degrees of tilt elevation down from vertical, unless I’ve misinterpreted it. Maybe it’s tilt direction around from ‘north’?
I was using the default settings for the tilt pencil, so tilt elevation was controlling brush size. I’m not sure what you mean by “what is your stylus output supposed to be”, could you elaborate? Your explanation makes it sound like a driver issue, but it also occurs when using the vendor-supplied drivers on Windows, which is puzzling. I wonder if it might just be an issue in the design of the tablet itself.
I’m almost positive it means 60 degrees of tilt elevation from vertical.
If you’re using c) Pencil-5 Tilted with the default settings, its size is controlled by tilt elevation and its rotation is controlled by tilt direction.
In your video, you were varying tilt direction (I assume you were keeping tilt elevation more or less constant) and so the rotation of the brush tip was varying, as might be expected.
From what I saw in your video, it does produce a varying output for tilt direction, but over a very limited range and with a step transition in the output.
What happens to the brush outline if you vary the tilt elevation? i.e, if you have it almost laying flat on the tabet varying up to standing vertically on the tablet?
I’ve never used a tilt sensitive stylus so I don’t know what they’re supposed to do (in detail).
The standard transfer curve for tilt elevation is a straight line with input 90-0 degrees and an output of 0-100 %. I assume you’ll get an input value (from the stylus) of 90 - 30 at the most and you should see some size variation with tilt elevation using the c) Pencil-5 Tilted brush preset with default settings.
You need to examine the tilt output(s) from your stylus by isolating the elevation from the direction. You do that by turning off all control inputs except for having tilt elevation control brush rotation and seeing how far you can vary it. Then have tilt direction control brush rotation and see how far you can vary it. At the moment, it’s not clear if your stylus produces a tilt direction output or a tilt elevation output (or both?)
I get smooth transitions around horizontal/vertical rotation if I link the rotation with pressure, tilt direction, X tilt, or Y tilt. Though with the latter three, the rotation doesn’t seem to reverse when the pen is exactly vertical like I’d expect–it gets erratic when the elevation is close to vertical and then similarly “snaps” to another rotation when I move the elevation far enough from 0. It seems like my stylus might be producing separate X and Y tilt angle outputs which are combined mathematically to get the tilt elevation and angle, but those X and Y outputs get unreliable when they are close to 0 and tend to snap from one side of sensing vertical to the other. I wish I could directly view the tilt outputs my tablet is producing instead of having to link them to a brush.
Also, I noticed that the X tilt and Y tilt go from -30 to 30 degrees. Is this supposed to be 0 to 60?
Understanding what the stylus is giving you, in detail, is definitely a confusing task. I’d have thought that the manufacturer should be able to tell you the details, at least about what it was supposed to do.
I’ve no idea where X tilt and Y tilt come from but they could be derived from elevation and direction values. You’d need a developer to explain that to you. As for the internal input range of -30 to +30 degrees for those control inputs, that does seem to suggest that a range of 60 degrees is some kind of standard expectation, maybe as +/- 30 around a ‘neutral’ position? Again, you’d need a developer to explain the details.
It would be useful to be able to see the tilt related values in the same way that you can directly see the pressure input values and the tablet/stylus button actions in the tablet tester. You could raise that topic as a suggested improvement.
If the stylus is vertical then small wobbles would give a large change in direction and that may be what is happening there, assuming it is giving an output related to direction.
Until you understand what the stylus actually does and gives, in terms of its outputs, then it will be difficult to design/modify a brush preset to properly make use of it in a predictable way. I wish you luck, I really do.
Just want to leave this here in case someone else stumbles upon this.
This is an Xp-Pen issue it cannot be fixed with any software as of now. It’s an issues that needs a firmwared update but there are some difficulties and xp-pen so far doesn’t know when (or if at all) they will be able to make a firmware update.
It’s a common problem with xp-pen tablet’s tilt function across at this point probably all products supporting the tilt functionality.
Note: Wacom so far is probably the only company with decently working tilt functionality, Huion has similar issues to xp-pen (everything applies to as of now) - though I can’t confirm if it’s on all products or only with specific lines of pen displays.
