GPencil: Add more types of stroke extensions when filling

The motivation for this change: while working on an animation recently, I found that there are some gaps that won't close easily via stroke extension or leak size checking. In D14698, I attempted to address this by changing the algorithm of the raster-space flood fill. This patch attempts to address the same issue in vector space by adding two new cases where stroke extensions are added, as suggested by @frogstomp:

  # **Points of high curvature:** when the curvature at a point is high enough that it's hard to visually distinguish between it and an endpoint, add a stroke extension out along the normal (pointing in the opposite direction of the stroke's acceleration.) This addresses cases where technically the endpoint points up, but there's a sharp corner right below it that should extend to connect.

  # **Stroke endpoints within a radius**: when two endpoints are close together, regardless of the angle they make, connect them if they are within a radius. This addresses cases like where the two endpoints have effectively parallel tangents, so extensions won't close the gap.

Reviewed By: antoniov, mendio, frogstomp

Differential Revision: https://developer.blender.org/D14809

1 files changed, 4 insertions, 0 deletions

diff --git a/release/scripts/startup/bl_ui/space_view3d_toolbar.py b/release/scripts/startup/bl_ui/space_view3d_toolbar.py
index 78e7932433e..88add2a8f3b 100644
--- a/release/scripts/startup/bl_ui/space_view3d_toolbar.py
+++ b/release/scripts/startup/bl_ui/space_view3d_toolbar.py
@@ -1607,6 +1607,10 @@ class VIEW3D_PT_tools_grease_pencil_brush_advanced(View3DPanel, Panel):
 
                 col.separator()
                 row = col.row(align=True)
+                row.prop(gp_settings, "fill_extend_mode")
+
+                col.separator()
+                row = col.row(align=True)
                 row.prop(gp_settings, "extend_stroke_factor")
                 row.prop(
                     gp_settings,