GPencil: Smooth thickness when joining strokes

When joining two strokes in paint mode using the auto merge option, the join was very hard if the thickness was too different.

This patch adds a smooth to the join in order to get better transition.

Also fixed the problem to join existing strokes very far from actual stroke.

Some cleanup and rename of old code is included in order to make code more readable.

Reviewed By: pepeland

Differential Revision: https://developer.blender.org/D12362

1 files changed, 7 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_gpencil.h b/source/blender/editors/include/ED_gpencil.h
index 8a8d91a570c..c760b661373 100644
--- a/source/blender/editors/include/ED_gpencil.h
+++ b/source/blender/editors/include/ED_gpencil.h
@@ -391,8 +391,15 @@ struct bGPDstroke *ED_gpencil_stroke_nearest_to_ends(struct bContext *C,
                                                      struct bGPDlayer *gpl,
                                                      struct bGPDframe *gpf,
                                                      struct bGPDstroke *gps,
+                                                     const float ctrl1[2],
+                                                     const float ctrl2[2],
                                                      const float radius,
                                                      int *r_index);
+void ED_gpencil_stroke_extremes_to2d(const struct GP_SpaceConversion *gsc,
+                                     const float diff_mat[4][4],
+                                     struct bGPDstroke *gps,
+                                     float r_ctrl1[2],
+                                     float r_ctrl2[2]);
 
 struct bGPDstroke *ED_gpencil_stroke_join_and_trim(struct bGPdata *gpd,
                                                    struct bGPDframe *gpf,