fix [#30257] bmesh: Rip "V" don't work on end vertex

added option to edgesplit bmesh operator to take tagged vertices as well so an edge at a boundary can split without splitting off the boundary vertex.

the behavior/speed of the edge split modifier and tool remainss the same, this is only used for rip.

source/blender/bmesh/intern/bmesh_opdefines.c

@@ -893,6 +893,9 @@ static BMOpDefine bmo_edgesplit_def = {
 	"edgesplit",
 	{{BMO_OP_SLOT_ELEMENT_BUF, "edges"}, /* input edges */
 	 {BMO_OP_SLOT_ELEMENT_BUF, "edgeout"}, /* old output disconnected edges */
+	 /* needed for vertex rip so we can rip only half an edge at a boundary wich would otherwise split off */
+	 {BMO_OP_SLOT_ELEMENT_BUF, "verts"}, /* optional tag verts, use to have greater control of splits */
+	 {BMO_OP_SLOT_BOOL,        "use_verts"}, /* use 'verts' for splitting, else just find verts to split from edges */
 	 {0} /* null-terminating sentine */},
 	bmo_edgesplit_exec,
 	BMO_OP_FLAG_UNTAN_MULTIRES

source/blender/bmesh/operators/bmo_edgesplit.c

@@ -32,6 +32,10 @@ enum {
 	EDGE_SEAM  = 1
 };
 
+enum {
+	VERT_SEAM  = 2
+};
+
 /**
  * Remove the EDGE_SEAM flag for edges we cant split
  *
@@ -88,13 +92,35 @@ static void bm_edgesplit_validate_seams(BMesh *bm, BMOperator *op)
 	MEM_freeN(vtouch);
 }
 
+/* keep this operator fast, its used in a modifier */
 void bmo_edgesplit_exec(BMesh *bm, BMOperator *op)
 {
 	BMOIter siter;
 	BMEdge *e;
+	const int use_verts = BMO_slot_bool_get(op, "use_verts");
 
 	BMO_slot_buffer_flag_enable(bm, op, "edges", BM_EDGE, EDGE_SEAM);
 
+	if (use_verts) {
+		/* this slows down the operation but its ok because the modifier doesn't use */
+		BMO_slot_buffer_flag_enable(bm, op, "verts", BM_VERT, VERT_SEAM);
+
+		/* prevent one edge having both verts unflagged
+		 * we could alternately disable these edges, either way its a corner case.
+		 *
+		 * This is needed so we don't split off the edge but then none of its verts which
+		 * would leave a duplicate edge.
+		 */
+		BMO_ITER(e, &siter, bm, op, "edges", BM_EDGE) {
+			if (UNLIKELY((BMO_elem_flag_test(bm, e->v1, VERT_SEAM) == FALSE &&
+			              (BMO_elem_flag_test(bm, e->v2, VERT_SEAM) == FALSE))))
+			{
+				BMO_elem_flag_enable(bm, e->v1, VERT_SEAM);
+				BMO_elem_flag_enable(bm, e->v2, VERT_SEAM);
+			}
+		}
+	}
+
 	bm_edgesplit_validate_seams(bm, op);
 
 	BMO_ITER(e, &siter, bm, op, "edges", BM_EDGE) {
@@ -108,6 +134,17 @@ void bmo_edgesplit_exec(BMesh *bm, BMOperator *op)
 		}
 	}
 
+	if (use_verts) {
+		BMO_ITER(e, &siter, bm, op, "edges", BM_EDGE) {
+			if (BMO_elem_flag_test(bm, e->v1, VERT_SEAM) == FALSE) {
+				BM_elem_flag_disable(e->v1, BM_ELEM_TAG);
+			}
+			if (BMO_elem_flag_test(bm, e->v2, VERT_SEAM) == FALSE) {
+				BM_elem_flag_disable(e->v2, BM_ELEM_TAG);
+			}
+		}
+	}
+
 	BMO_ITER(e, &siter, bm, op, "edges", BM_EDGE) {
 		if (BMO_elem_flag_test(bm, e, EDGE_SEAM)) {
 			if (BM_elem_flag_test(e->v1, BM_ELEM_TAG)) {

source/blender/editors/mesh/editmesh_tools.c

@@ -1227,9 +1227,7 @@ static int edbm_edge_split_exec(bContext *C, wmOperator *op)
 	BMOperator bmop;
 	int len = 0;
 	
-	if (!EDBM_InitOpf(em, &bmop, op, "edgesplit edges=%he",
+	if (!EDBM_InitOpf(em, &bmop, op, "edgesplit edges=%he", BM_ELEM_SELECT)) {
-	                  BM_ELEM_SELECT))
-	{
 		return OPERATOR_CANCELLED;
 	}
 	BMO_op_exec(bm, &bmop);
@@ -2305,7 +2303,8 @@ static int edbm_rip_invoke(bContext *C, wmOperator *op, wmEvent *event)
 		}
 	}
 
-	if (!EDBM_InitOpf(em, &bmop, op, "edgesplit edges=%he", BM_ELEM_TAG)) {
+	if (!EDBM_InitOpf(em, &bmop, op, "edgesplit edges=%he verts=%hv use_verts=%b",
+	                  BM_ELEM_TAG, BM_ELEM_SELECT, TRUE)) {
 		return OPERATOR_CANCELLED;
 	}