Sculpt: Experimental Pen Tilt Support

This adds support for pen tilt in sculpt mode. For now, pen tilt is used
by tweaking the tilt strength property, which controls how much the pen
angle affects the sculpt normal. This is available in Draw, Draw Sharp,
Flatten, Fill, Scrape and Clay Strips brushes, but it can be enabled in
more tools later.

The purpose of this patch is to have a usable implementation of pen tilt
in a painting mode, so users can test and see in which hardware and
platforms this feature is supported and how well it works. If it works
ok, more tools and features that rely on pen tilt can be implemented,
like brushes that blend between two deformations depending on the angle.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D8893

1 files changed, 3 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_brush_types.h b/source/blender/makesdna/DNA_brush_types.h
index 3acdbbb79fa..8437d782e98 100644
--- a/source/blender/makesdna/DNA_brush_types.h
+++ b/source/blender/makesdna/DNA_brush_types.h
@@ -568,10 +568,12 @@ typedef struct Brush {
   char gpencil_sculpt_tool;
   /** Active grease pencil weight tool. */
   char gpencil_weight_tool;
-  char _pad1[2];
+  char _pad1[6];
 
   float autosmooth_factor;
 
+  float tilt_strength_factor;
+
   float topology_rake_factor;
 
   float crease_pinch_factor;