Select nth option to skip steps

Patch T43752 @codemanx, added matching curve option.

3 files changed, 32 insertions, 23 deletions

diff --git a/source/blender/editors/curve/editcurve.c b/source/blender/editors/curve/editcurve.c
index 936a40b83b6..cbbee2f206f 100644
--- a/source/blender/editors/curve/editcurve.c
+++ b/source/blender/editors/curve/editcurve.c
@@ -6142,7 +6142,7 @@ void CURVE_OT_select_random(wmOperatorType *ot)
 
 /********************* every nth number of point *******************/
 
-static void select_nth_bezt(Nurb *nu, BezTriple *bezt, int nth)
+static void select_nth_bezt(Nurb *nu, BezTriple *bezt, int nth, int skip, int offset)
 {
 	int a, start;
 
@@ -6151,7 +6151,8 @@ static void select_nth_bezt(Nurb *nu, BezTriple *bezt, int nth)
 	bezt = &nu->bezt[a - 1];
 
 	while (a--) {
-		if (abs(start - a) % nth) {
+		const int depth = abs(start - a);
+		if ((offset + depth) % (skip + nth) >= skip) {
 			select_beztriple(bezt, DESELECT, SELECT, HIDDEN);
 		}
 
@@ -6159,10 +6160,10 @@ static void select_nth_bezt(Nurb *nu, BezTriple *bezt, int nth)
 	}
 }
 
-static void select_nth_bp(Nurb *nu, BPoint *bp, int nth)
+static void select_nth_bp(Nurb *nu, BPoint *bp, int nth, int skip, int offset)
 {
 	int a, startrow, startpnt;
-	int dist, row, pnt;
+	int row, pnt;
 
 	startrow = (bp - nu->bp) / nu->pntsu;
 	startpnt = (bp - nu->bp) % nu->pntsu;
@@ -6173,8 +6174,8 @@ static void select_nth_bp(Nurb *nu, BPoint *bp, int nth)
 	pnt = nu->pntsu - 1;
 
 	while (a--) {
-		dist = abs(pnt - startpnt) + abs(row - startrow);
-		if (dist % nth) {
+		const int depth = abs(pnt - startpnt) + abs(row - startrow);
+		if ((offset + depth) % (skip + nth) >= skip) {
 			select_bpoint(bp, DESELECT, SELECT, HIDDEN);
 		}
 
@@ -6188,7 +6189,7 @@ static void select_nth_bp(Nurb *nu, BPoint *bp, int nth)
 	}
 }
 
-bool ED_curve_select_nth(Curve *cu, int nth)
+bool ED_curve_select_nth(Curve *cu, int nth, int skip, int offset)
 {
 	Nurb *nu = NULL;
 	void *vert = NULL;
@@ -6197,10 +6198,10 @@ bool ED_curve_select_nth(Curve *cu, int nth)
 		return false;
 
 	if (nu->bezt) {
-		select_nth_bezt(nu, vert, nth);
+		select_nth_bezt(nu, vert, nth, skip, offset);
 	}
 	else {
-		select_nth_bp(nu, vert, nth);
+		select_nth_bp(nu, vert, nth, skip, offset);
 	}
 
 	return true;
@@ -6209,9 +6210,14 @@ bool ED_curve_select_nth(Curve *cu, int nth)
 static int select_nth_exec(bContext *C, wmOperator *op)
 {
 	Object *obedit = CTX_data_edit_object(C);
-	int nth = RNA_int_get(op->ptr, "nth");
+	const int nth = RNA_int_get(op->ptr, "nth") - 1;
+	const int skip = RNA_int_get(op->ptr, "skip");
+	int offset = RNA_int_get(op->ptr, "offset");
 
-	if (!ED_curve_select_nth(obedit->data, nth)) {
+	/* so input of offset zero ends up being (nth - 1) */
+	offset = mod_i(offset, nth + skip);
+
+	if (!ED_curve_select_nth(obedit->data, nth, skip, offset)) {
 		if (obedit->type == OB_SURF) {
 			BKE_report(op->reports, RPT_ERROR, "Surface has not got active point");
 		}
@@ -6242,6 +6248,8 @@ void CURVE_OT_select_nth(wmOperatorType *ot)
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
 	RNA_def_int(ot->srna, "nth", 2, 2, INT_MAX, "Nth Selection", "", 2, 100);
+	RNA_def_int(ot->srna, "skip", 1, 1, INT_MAX, "Skip", "", 1, 100);
+	RNA_def_int(ot->srna, "offset", 0, INT_MIN, INT_MAX, "Offset", "", -100, 100);
 }
 
 /********************** add duplicate operator *********************/
diff --git a/source/blender/editors/include/ED_curve.h b/source/blender/editors/include/ED_curve.h
index 27e9cad4fd5..982e17cfce4 100644
--- a/source/blender/editors/include/ED_curve.h
+++ b/source/blender/editors/include/ED_curve.h
@@ -79,7 +79,7 @@ void    free_editText(struct Object *obedit);
 
 void    ED_text_to_object(struct bContext *C, struct Text *text, const bool split_lines);
 
-bool ED_curve_select_nth(struct Curve *cu, int nth);
+bool ED_curve_select_nth(struct Curve *cu, int nth, int skip, int offset);
 
 void ED_curve_beztcpy(struct EditNurb *editnurb, struct BezTriple *dst, struct BezTriple *src, int count);
 void ED_curve_bpcpy(struct EditNurb *editnurb, struct BPoint *dst, struct BPoint *src, int count);
diff --git a/source/blender/editors/mesh/editmesh_select.c b/source/blender/editors/mesh/editmesh_select.c
index d3073d519f6..c020243c8ff 100644
--- a/source/blender/editors/mesh/editmesh_select.c
+++ b/source/blender/editors/mesh/editmesh_select.c
@@ -2552,7 +2552,7 @@ static bool bm_edge_is_select_isolated(BMEdge *e)
 /* Walk all reachable elements of the same type as h_act in breadth-first
  * order, starting from h_act. Deselects elements if the depth when they
  * are reached is not a multiple of "nth". */
-static void walker_deselect_nth(BMEditMesh *em, int nth, int offset, BMHeader *h_act)
+static void walker_deselect_nth(BMEditMesh *em, int nth, int skip, int offset, BMHeader *h_act)
 {
 	BMElem *ele;
 	BMesh *bm = em->bm;
@@ -2618,7 +2618,8 @@ static void walker_deselect_nth(BMEditMesh *em, int nth, int offset, BMHeader *h
 	for (ele = BMW_begin(&walker, h_act); ele != NULL; ele = BMW_step(&walker)) {
 		if (!BM_elem_flag_test(ele, BM_ELEM_TAG)) {
 			/* Deselect elements that aren't at "nth" depth from active */
-			if ((offset + BMW_current_depth(&walker)) % nth) {
+			const int depth = BMW_current_depth(&walker) - 1;
+			if ((offset + depth) % (skip + nth) >= skip) {
 				BM_elem_select_set(bm, ele, false);
 			}
 			BM_elem_flag_enable(ele, BM_ELEM_TAG);
@@ -2685,7 +2686,7 @@ static void deselect_nth_active(BMEditMesh *em, BMVert **r_eve, BMEdge **r_eed,
 	}
 }
 
-static bool edbm_deselect_nth(BMEditMesh *em, int nth, int offset)
+static bool edbm_deselect_nth(BMEditMesh *em, int nth, int skip, int offset)
 {
 	BMVert *v;
 	BMEdge *e;
@@ -2694,15 +2695,15 @@ static bool edbm_deselect_nth(BMEditMesh *em, int nth, int offset)
 	deselect_nth_active(em, &v, &e, &f);
 
 	if (v) {
-		walker_deselect_nth(em, nth, offset, &v->head);
+		walker_deselect_nth(em, nth, skip, offset, &v->head);
 		return true;
 	}
 	else if (e) {
-		walker_deselect_nth(em, nth, offset, &e->head);
+		walker_deselect_nth(em, nth, skip, offset, &e->head);
 		return true;
 	}
 	else if (f) {
-		walker_deselect_nth(em, nth, offset, &f->head);
+		walker_deselect_nth(em, nth, skip, offset, &f->head);
 		return true;
 	}
 
@@ -2713,15 +2714,14 @@ static int edbm_select_nth_exec(bContext *C, wmOperator *op)
 {
 	Object *obedit = CTX_data_edit_object(C);
 	BMEditMesh *em = BKE_editmesh_from_object(obedit);
-	const int nth = RNA_int_get(op->ptr, "nth");
+	const int nth = RNA_int_get(op->ptr, "nth") - 1;
+	const int skip = RNA_int_get(op->ptr, "skip");
 	int offset = RNA_int_get(op->ptr, "offset");
 
 	/* so input of offset zero ends up being (nth - 1) */
-	offset = mod_i(offset, nth);
-	/* depth starts at 1, this keeps active item selected */
-	offset -= 1;
+	offset = mod_i(offset, nth + skip);
 
-	if (edbm_deselect_nth(em, nth, offset) == false) {
+	if (edbm_deselect_nth(em, nth, skip, offset) == false) {
 		BKE_report(op->reports, RPT_ERROR, "Mesh has no active vert/edge/face");
 		return OPERATOR_CANCELLED;
 	}
@@ -2747,6 +2747,7 @@ void MESH_OT_select_nth(wmOperatorType *ot)
 	ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
 	RNA_def_int(ot->srna, "nth", 2, 2, INT_MAX, "Nth Selection", "", 2, 100);
+	RNA_def_int(ot->srna, "skip", 1, 1, INT_MAX, "Skip", "", 1, 100);
 	RNA_def_int(ot->srna, "offset", 0, INT_MIN, INT_MAX, "Offset", "", -100, 100);
 }