Fix T67545: GPencil - New Merge by Distance operator

Merge points when the distance is less than a predefined value.

The method to interpolate the position created a wrong merge. Now, always the secondary point is merged with the first one (merge at first), except the last point.

3 files changed, 72 insertions, 0 deletions

diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil/gpencil_edit.c
index 277628f4363..a7b9bb24bf8 100644
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil/gpencil_edit.c
@@ -4522,3 +4522,73 @@ bool ED_object_gpencil_exit(struct Main *bmain, Object *ob)
   }
   return ok;
 }
+
+/* ** merge by distance *** */
+bool gp_merge_by_distance_poll(bContext *C)
+{
+  Object *ob = CTX_data_active_object(C);
+  if (ob == NULL) {
+    return false;
+  }
+  bGPdata *gpd = (bGPdata *)ob->data;
+  if (gpd == NULL) {
+    return false;
+  }
+
+  bGPDlayer *gpl = BKE_gpencil_layer_getactive(gpd);
+
+  return ((gpl != NULL) && (ob->mode == OB_MODE_EDIT_GPENCIL));
+}
+
+static int gp_merge_by_distance_exec(bContext *C, wmOperator *op)
+{
+  Object *ob = CTX_data_active_object(C);
+  bGPdata *gpd = (bGPdata *)ob->data;
+  const float threshold = RNA_float_get(op->ptr, "threshold");
+  const bool unselected = RNA_boolean_get(op->ptr, "use_unselected");
+
+  /* sanity checks */
+  if (ELEM(NULL, gpd)) {
+    return OPERATOR_CANCELLED;
+  }
+
+  /* Go through each editable selected stroke */
+  GP_EDITABLE_STROKES_BEGIN (gpstroke_iter, C, gpl, gps) {
+    if (gps->flag & GP_STROKE_SELECT) {
+      BKE_gpencil_merge_distance_stroke(gpf_, gps, threshold, unselected);
+    }
+  }
+  GP_EDITABLE_STROKES_END(gpstroke_iter);
+
+  /* notifiers */
+  DEG_id_tag_update(&gpd->id, ID_RECALC_TRANSFORM | ID_RECALC_GEOMETRY);
+  WM_event_add_notifier(C, NC_GPENCIL | ND_DATA | NA_EDITED, NULL);
+
+  return OPERATOR_FINISHED;
+}
+
+void GPENCIL_OT_stroke_merge_by_distance(wmOperatorType *ot)
+{
+  PropertyRNA *prop;
+
+  /* identifiers */
+  ot->name = "Merge by Distance";
+  ot->idname = "GPENCIL_OT_stroke_merge_by_distance";
+  ot->description = "Merge points by distance";
+
+  /* api callbacks */
+  ot->exec = gp_merge_by_distance_exec;
+  ot->poll = gp_merge_by_distance_poll;
+
+  /* flags */
+  ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
+
+  /* properties */
+  prop = RNA_def_float(ot->srna, "threshold", 0.001f, 0.0f, 100.0f, "Threshold", "", 0.0f, 100.0f);
+  /* avoid re-using last var */
+  RNA_def_property_flag(prop, PROP_SKIP_SAVE);
+
+  prop = RNA_def_boolean(
+      ot->srna, "use_unselected", 0, "Unselected", "Use whole stroke, not only selected points");
+  RNA_def_property_flag(prop, PROP_SKIP_SAVE);
+}
diff --git a/source/blender/editors/gpencil/gpencil_intern.h b/source/blender/editors/gpencil/gpencil_intern.h
index 1c20da4bed3..3776dd09eb5 100644
--- a/source/blender/editors/gpencil/gpencil_intern.h
+++ b/source/blender/editors/gpencil/gpencil_intern.h
@@ -489,6 +489,7 @@ void GPENCIL_OT_stroke_smooth(struct wmOperatorType *ot);
 void GPENCIL_OT_stroke_merge(struct wmOperatorType *ot);
 void GPENCIL_OT_stroke_cutter(struct wmOperatorType *ot);
 void GPENCIL_OT_stroke_trim(struct wmOperatorType *ot);
+void GPENCIL_OT_stroke_merge_by_distance(struct wmOperatorType *ot);
 
 void GPENCIL_OT_brush_presets_create(struct wmOperatorType *ot);
 
diff --git a/source/blender/editors/gpencil/gpencil_ops.c b/source/blender/editors/gpencil/gpencil_ops.c
index a1645a5c67d..54e99802c54 100644
--- a/source/blender/editors/gpencil/gpencil_ops.c
+++ b/source/blender/editors/gpencil/gpencil_ops.c
@@ -317,6 +317,7 @@ void ED_operatortypes_gpencil(void)
   WM_operatortype_append(GPENCIL_OT_stroke_merge);
   WM_operatortype_append(GPENCIL_OT_stroke_cutter);
   WM_operatortype_append(GPENCIL_OT_stroke_trim);
+  WM_operatortype_append(GPENCIL_OT_stroke_merge_by_distance);
 
   WM_operatortype_append(GPENCIL_OT_brush_presets_create);