Implement basic global tablet pressure curve options.

Grease Pencil already implements support for full-featured
per-brush pressure curves, but it is useful to have some
basic global settings that affect all brushes and tools.

This adds two simple options:

- Raw pressure required to achieve full brush intensity.
- Softness control, using a gamma curve internally.

The most important one is the max pressure setting, because it is
critical for ergonomics, but the Linux Wacom driver lacks it.

The softness option internally converts to gamma = 4^-softness.

Reviewers: brecht, campbellbarton

Differential Revision: https://developer.blender.org/D3967

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/windowmanager/wm_event_system.h b/source/blender/windowmanager/wm_event_system.h
index a0610ffcff3..fe28cbf9895 100644
--- a/source/blender/windowmanager/wm_event_system.h
+++ b/source/blender/windowmanager/wm_event_system.h
@@ -101,6 +101,8 @@ void        wm_event_do_depsgraph(bContext *C);
 void        wm_event_do_refresh_wm_and_depsgraph(bContext *C);
 void        wm_event_do_notifiers(bContext *C);
 
+float       wm_pressure_curve(float raw_pressure);
+
 /* wm_keymap.c */
 
 /* wm_dropbox.c */