iPad Pressure Curve Input Bug - Initial Input Value Stuck

[Robert Hansford]

Hey guys, hope all is well!

I ran into a strange behavior on iPad last night that I thought I'd share. I'm on 1.10.3, Late 2020 iPad Pro 12.9, using 2nd gen apple pencil. iPad running OS 15.1, M1 Mac running Monterey 12.0.1

So, I was working on a drawing using some vector inking brushes I made. The size variance of the brushes is set to 100%, and the brushes were designed to produce very fine tapered points. Everything was going fine until suddenly I started getting really strange results from my strokes.

No matter how lightly or heavily I touch the screen with the pencil the initial input value appears to be stuck at the exact same value/percentage which indicates to me that the error/bug is consistent. The ends of the strokes didn't appear to be affected, and I was able to produce a variety of values at the ends of strokes. Only the initial contact/input seems to be affected.

I'll attach a video I took of the behavior below, as well as video of a test I ran using my iPad to draw on the M1 Mini in Designer.

Here are some notes regarding the testing I performed.

1. At first I thought it might have been either my own hand or the apple pencil. So I opened up a few other apps like procreate and Vectornator and tested it out. The behavior was not successfully reproduced.

2. I went back into Designer's pencil settings, reset the pressure curve, and tried to produce the behavior again. The behavior was successfully reproduced.

3. Then, I opened up the 1.10.3(1.10.19)beta and tried again. The behavior was successfully reproduced.

4. After this, I wondered if the phenomenon was isolated to the iPad versions of the app, so I opened up Designer on the M1, hooked up the iPad and recorded. The behavior was not successfully reproduced; input from the Apple pencil appeared as normal.

Thank you for your time. Keep at it!

 

[Sean P]

Hi Robert,

Thanks for the information and videos. What you're seeing is actually a workaround we've implemented due to a problem with the hardware sending an incorrect high pressure value at the start of the stroke. This was causing 'blobs' to appear at the start of a stroke when using a low pressure. To work around this we've limited the initial pressure to 20%, which is why you're seeing the pressure values you are.

Unfortunately this isn't the most ideal of situations and it is something we're wanting to improve in the future!

[Robert Hansford]

Dang. This is unfortunate, but I've got to admit its fascinating. So many questions! - Alas, It sounds like you guys have your hands full. I hope you guys can get it sorted well. Take care! I'll be looking forward to all the good stuff coming down the pike!

[Robert Hansford]

Quote

...a problem with the hardware sending an incorrect high pressure value at the start of the stroke. This was causing 'blobs' to appear at the start of a stroke when using a low pressure. To work around this we've limited the initial pressure to 20%...

Sean, is this adjustment limited to Vector Persona or was it implemented in Pixel Persona as well? I'm wondering how this will effect pressure sensitive brushes and shaders in Pixel Persona.

[Bryan Rieger]

Just bumping this Affinity Designer / Apple Pencil issue on iPad as it's still driving me nuts in v2. Every time I draw a line using the vector pencil or brush I often get additional data (points, pressure, etc) at the beginning and end of the stroke. Cleaning this up is SO tedious, especially as we still don't have a stroke width tool which means you still have to edit widths in the awful (and very small) pressure graph.

After all these years (9+ with Affinity Designer on macOS, since November 2017 on iPad, and 2 major versions) this is something I would have expected to be fixed (as a priority) years ago. It's supposed to be a bloody drawing app?!