GPencil: Only brushes with pinned materials have materials

Using GP_BRUSH_MATERIAL_PINNED to switch between active material and brush material, instead of updating all brushes on active material changes. This will allow brushes to have no material and therefore to not inflate the user count.

This fix T62465.

Patch contributed by @matc
Reviewers: @brecht @antoniov @billreynish @mendio

11 files changed, 77 insertions, 199 deletions

diff --git a/source/blender/editors/gpencil/gpencil_add_monkey.c b/source/blender/editors/gpencil/gpencil_add_monkey.c
index a4fbd4002fa..cd28043a6fe 100644
--- a/source/blender/editors/gpencil/gpencil_add_monkey.c
+++ b/source/blender/editors/gpencil/gpencil_add_monkey.c
@@ -60,11 +60,10 @@ static int gpencil_monkey_color(
 		}
 	}
 
+	int idx;
+
 	/* create a new one */
-	BKE_object_material_slot_add(bmain, ob);
-	ma = BKE_material_add_gpencil(bmain, pct->name);
-	assign_material(bmain, ob, ma, ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-	id_us_min(&ma->id);
+	ma = BKE_gpencil_handle_new_material(bmain, ob, pct->name, &idx);
 
 	copy_v4_v4(ma->gp_style->stroke_rgba, pct->line);
 	copy_v4_v4(ma->gp_style->fill_rgba, pct->fill);
@@ -80,7 +79,7 @@ static int gpencil_monkey_color(
 		ma->gp_style->flag |= GP_STYLE_FILL_SHOW;
 	}
 
-	return BKE_gpencil_get_material_index(ob, ma) - 1;
+	return idx;
 }
 
 /* ***************************************************************** */
@@ -1447,10 +1446,6 @@ void ED_gpencil_create_monkey(bContext *C, Object *ob, float mat[4][4])
 
 	/* set first color as active */
 	ob->actcol = color_Black + 1;
-	Material *ma = give_current_material(ob, ob->actcol);
-	if (ma != NULL) {
-		BKE_brush_update_material(bmain, ma, NULL);
-	}
 
 	/* layers */
 	/* NOTE: For now, we just add new layers, to make it easier to separate out old/new instances */
diff --git a/source/blender/editors/gpencil/gpencil_add_stroke.c b/source/blender/editors/gpencil/gpencil_add_stroke.c
index 8b261bf798b..c56cb94c58d 100644
--- a/source/blender/editors/gpencil/gpencil_add_stroke.c
+++ b/source/blender/editors/gpencil/gpencil_add_stroke.c
@@ -60,11 +60,10 @@ static int gp_stroke_material(
 		}
 	}
 
+	int idx;
+
 	/* create a new one */
-	BKE_object_material_slot_add(bmain, ob);
-	ma = BKE_material_add_gpencil(bmain, pct->name);
-	assign_material(bmain, ob, ma, ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-	id_us_min(&ma->id);
+	ma = BKE_gpencil_handle_new_material(bmain, ob, pct->name, &idx);
 
 	copy_v4_v4(ma->gp_style->stroke_rgba, pct->line);
 	copy_v4_v4(ma->gp_style->fill_rgba, pct->fill);
@@ -73,7 +72,7 @@ static int gp_stroke_material(
 		ma->gp_style->flag |= GP_STYLE_FILL_SHOW;
 	}
 
-	return BKE_gpencil_get_material_index(ob, ma) - 1;
+	return idx;
 }
 
 /* ***************************************************************** */
@@ -231,10 +230,6 @@ void ED_gpencil_create_stroke(bContext *C, Object *ob, float mat[4][4])
 
 	/* set first color as active and in brushes */
 	ob->actcol = color_black + 1;
-	Material *ma = give_current_material(ob, ob->actcol);
-	if (ma != NULL) {
-		BKE_brush_update_material(bmain, ma, NULL);
-	}
 
 	/* layers */
 	bGPDlayer *colors = BKE_gpencil_layer_addnew(gpd, "Colors", false);
diff --git a/source/blender/editors/gpencil/gpencil_brush.c b/source/blender/editors/gpencil/gpencil_brush.c
index 6e8dd11ee2f..6b646566996 100644
--- a/source/blender/editors/gpencil/gpencil_brush.c
+++ b/source/blender/editors/gpencil/gpencil_brush.c
@@ -1101,14 +1101,10 @@ static void gp_brush_clone_add(bContext *C, tGP_BrushEditData *gso)
 
 			/* Fix color references */
 			Material *ma = BLI_ghash_lookup(data->new_colors, &new_stroke->mat_nr);
-			if ((ma) && (BKE_gpencil_get_material_index(ob, ma) > 0)) {
-				gps->mat_nr = BKE_gpencil_get_material_index(ob, ma) - 1;
-				CLAMP_MIN(gps->mat_nr, 0);
+			gps->mat_nr = BKE_gpencil_get_material_index(ob, ma);
+			if (!ma || gps->mat_nr) {
+				gps->mat_nr = 0;
 			}
-			else {
-				gps->mat_nr = 0; /* only if the color is not found */
-			}
-
 			/* Adjust all the stroke's points, so that the strokes
 			 * get pasted relative to where the cursor is now
 			 */
diff --git a/source/blender/editors/gpencil/gpencil_data.c b/source/blender/editors/gpencil/gpencil_data.c
index 2cdd772f726..a8b31b20182 100644
--- a/source/blender/editors/gpencil/gpencil_data.c
+++ b/source/blender/editors/gpencil/gpencil_data.c
@@ -514,15 +514,10 @@ static int gp_layer_duplicate_object_exec(bContext *C, wmOperator *op)
 			 * otherwise add the slot with the material
 			 */
 			Material *ma_src = give_current_material(ob_src, gps_src->mat_nr + 1);
-			int idx = BKE_gpencil_get_material_index(ob_dst, ma_src);
-			if (idx == 0) {
-				BKE_object_material_slot_add(bmain, ob_dst);
-				assign_material(bmain, ob_dst, ma_src, ob_dst->totcol, BKE_MAT_ASSIGN_USERPREF);
-				idx = ob_dst->totcol;
-			}
+			int idx = BKE_gpencil_handle_material(bmain, ob_dst, ma_src);
 
 			/* reasign the stroke material to the right slot in destination object */
-			gps_dst->mat_nr = idx - 1;
+			gps_dst->mat_nr = idx;
 
 			/* add new stroke to frame */
 			BLI_addtail(&gpf_dst->strokes, gps_dst);
@@ -1377,7 +1372,7 @@ static int gp_stroke_change_color_exec(bContext *C, wmOperator *op)
 		}
 	}
 	/* try to find slot */
-	int idx = BKE_gpencil_get_material_index(ob, ma) - 1;
+	int idx = BKE_gpencil_get_material_index(ob, ma);
 	if (idx < 0) {
 		return OPERATOR_CANCELLED;
 	}
@@ -2052,10 +2047,7 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
 
 				for (short i = 0; i < *totcol; i++) {
 					Material *tmp_ma = give_current_material(ob_src, i + 1);
-					if (BKE_gpencil_get_material_index(ob_dst, tmp_ma) == 0) {
-						BKE_object_material_slot_add(bmain, ob_dst);
-						assign_material(bmain, ob_dst, tmp_ma, ob_dst->totcol, BKE_MAT_ASSIGN_USERPREF);
-					}
+					BKE_gpencil_handle_material(bmain, ob_dst, tmp_ma);
 				}
 
 				/* duplicate bGPDlayers  */
@@ -2085,24 +2077,12 @@ int ED_gpencil_join_objects_exec(bContext *C, wmOperator *op)
 					invert_m4_m4(inverse_diff_mat, diff_mat);
 
 					Material *ma_src = NULL;
-					int idx;
 					for (bGPDframe *gpf = gpl_new->frames.first; gpf; gpf = gpf->next) {
 						for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
 
 							/* reasign material. Look old material and try to find in dst */
 							ma_src = give_current_material(ob_src, gps->mat_nr + 1);
-							if (ma_src != NULL) {
-								idx = BKE_gpencil_get_material_index(ob_dst, ma_src);
-								if (idx > 0) {
-									gps->mat_nr = idx - 1;
-								}
-								else {
-									gps->mat_nr = 0;
-								}
-							}
-							else {
-								gps->mat_nr = 0;
-							}
+							gps->mat_nr = BKE_gpencil_handle_material(bmain, ob_dst, ma_src);
 
 							bGPDspoint *pt;
 							int i;
diff --git a/source/blender/editors/gpencil/gpencil_edit.c b/source/blender/editors/gpencil/gpencil_edit.c
index a6b6fc2cbe7..259c9468e76 100644
--- a/source/blender/editors/gpencil/gpencil_edit.c
+++ b/source/blender/editors/gpencil/gpencil_edit.c
@@ -1074,10 +1074,7 @@ GHash *gp_copybuf_validate_colormap(bContext *C)
 		char *ma_name = BLI_ghashIterator_getValue(&gh_iter);
 		Material *ma = BLI_ghash_lookup(name_to_ma, ma_name);
 
-		if (ma != NULL && BKE_gpencil_get_material_index(ob, ma) == 0) {
-			BKE_object_material_slot_add(bmain, ob);
-			assign_material(bmain, ob, ma, ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-		}
+		BKE_gpencil_handle_material(bmain, ob, ma);
 
 		/* Store this mapping (for use later when pasting) */
 		if (!BLI_ghash_haskey(new_colors, POINTER_FROM_INT(*key))) {
@@ -1331,14 +1328,8 @@ static int gp_strokes_paste_exec(bContext *C, wmOperator *op)
 
 				/* Remap material */
 				Material *ma = BLI_ghash_lookup(new_colors, POINTER_FROM_INT(new_stroke->mat_nr));
-				if ((ma) && (BKE_gpencil_get_material_index(ob, ma) > 0)) {
-					new_stroke->mat_nr = BKE_gpencil_get_material_index(ob, ma) - 1;
-					CLAMP_MIN(new_stroke->mat_nr, 0);
-				}
-				else {
-					new_stroke->mat_nr = 0; /* only if the color is not found */
-				}
-
+				new_stroke->mat_nr = BKE_gpencil_get_material_index(ob, ma);
+				BLI_assert(new_stroke >= 0); /* have to add the material first */
 			}
 		}
 	}
@@ -3914,10 +3905,7 @@ static int gp_stroke_separate_exec(bContext *C, wmOperator *op)
 	/* create new grease pencil datablock */
 	gpd_dst = BKE_gpencil_data_addnew(bmain, gpd_src->id.name + 2);
 	ob_dst->data = (bGPdata *)gpd_dst;
-
-	int totslots = ob_dst->totcol;
-	int totadd = 0;
-
+	
 	/* loop old datablock and separate parts */
 	if ((mode == GP_SEPARATE_POINT) || (mode == GP_SEPARATE_STROKE)) {
 		CTX_DATA_BEGIN(C, bGPDlayer *, gpl, editable_gpencil_layers)
@@ -3962,21 +3950,8 @@ static int gp_stroke_separate_exec(bContext *C, wmOperator *op)
 							}
 
 							/* add duplicate materials */
-							ma = give_current_material(ob, gps->mat_nr + 1);
-							idx = BKE_gpencil_get_material_index(ob_dst, ma);
-							if (idx == 0) {
-
-								totadd++;
-								ob_dst->actcol = totadd;
-								ob_dst->totcol = totadd;
-
-								if (totadd > totslots) {
-									BKE_object_material_slot_add(bmain, ob_dst);
-								}
-
-								assign_material(bmain, ob_dst, ma, ob_dst->totcol, BKE_MAT_ASSIGN_USERPREF);
-								idx = totadd;
-							}
+							ma = give_current_material(ob, gps->mat_nr + 1); /* XXX same material can be in multiple slots */
+							idx = BKE_gpencil_handle_material(bmain, ob_dst, ma);
 
 							/* selected points mode */
 							if (mode == GP_SEPARATE_POINT) {
@@ -3984,7 +3959,7 @@ static int gp_stroke_separate_exec(bContext *C, wmOperator *op)
 								bGPDstroke *gps_dst = BKE_gpencil_stroke_duplicate(gps);
 
 								/* reasign material */
-								gps_dst->mat_nr = idx - 1;
+								gps_dst->mat_nr = idx;
 
 								/* link to destination frame */
 								BLI_addtail(&gpf_dst->strokes, gps_dst);
@@ -4010,7 +3985,7 @@ static int gp_stroke_separate_exec(bContext *C, wmOperator *op)
 								/* relink to destination frame */
 								BLI_addtail(&gpf_dst->strokes, gps);
 								/* reasign material */
-								gps->mat_nr = idx - 1;
+								gps->mat_nr = idx;
 							}
 						}
 					}
@@ -4048,21 +4023,7 @@ static int gp_stroke_separate_exec(bContext *C, wmOperator *op)
 						continue;
 					}
 					ma = give_current_material(ob, gps->mat_nr + 1);
-					idx = BKE_gpencil_get_material_index(ob_dst, ma);
-					if (idx == 0) {
-						totadd++;
-						ob_dst->actcol = totadd;
-						ob_dst->totcol = totadd;
-
-						if (totadd > totslots) {
-							BKE_object_material_slot_add(bmain, ob_dst);
-						}
-
-						assign_material(bmain, ob_dst, ma, ob_dst->totcol, BKE_MAT_ASSIGN_USERPREF);
-						idx = totadd;
-					}
-					/* reasign material */
-					gps->mat_nr = idx - 1;
+					gps->mat_nr = BKE_gpencil_handle_material(bmain, ob_dst, ma);
 				}
 			}
 		}
diff --git a/source/blender/editors/gpencil/gpencil_fill.c b/source/blender/editors/gpencil/gpencil_fill.c
index c8c57c8ffbf..a4b4b699e5e 100644
--- a/source/blender/editors/gpencil/gpencil_fill.c
+++ b/source/blender/editors/gpencil/gpencil_fill.c
@@ -1017,12 +1017,7 @@ static void gpencil_stroke_from_buffer(tGPDfill *tgpf)
 	gps->flag |= GP_STROKE_CYCLIC;
 	gps->flag |= GP_STROKE_3DSPACE;
 
-	gps->mat_nr = BKE_gpencil_get_material_index(tgpf->ob, tgpf->mat) - 1;
-	if (gps->mat_nr < 0) {
-		BKE_object_material_slot_add(tgpf->bmain, tgpf->ob);
-		assign_material(tgpf->bmain, tgpf->ob, tgpf->mat, tgpf->ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-		gps->mat_nr = tgpf->ob->totcol - 1;
-	}
+	gps->mat_nr = BKE_gpencil_handle_material(tgpf->bmain, tgpf->ob, tgpf->mat);
 
 	/* allocate memory for storage points */
 	gps->totpoints = tgpf->sbuffer_size;
@@ -1215,17 +1210,18 @@ static tGPDfill *gp_session_init_fill(bContext *C, wmOperator *UNUSED(op))
 	tgpf->fill_draw_mode = brush->gpencil_settings->fill_draw_mode;
 	tgpf->fill_factor = (short)max_ii(1, min_ii((int)brush->gpencil_settings->fill_factor, 8));
 
+	int totcol = tgpf->ob->totcol;
+
 	/* get color info */
-	Material *ma = BKE_gpencil_get_material_from_brush(brush);
-	/* if no brush defaults, get material and color info */
-	if ((ma == NULL) || (ma->gp_style == NULL)) {
-		ma = BKE_gpencil_material_ensure(bmain, tgpf->ob);
-		/* assign always the first material to the brush */
-		brush->gpencil_settings->material = give_current_material(tgpf->ob, 1);
-	}
+	Material *ma = BKE_gpencil_current_input_brush_material(bmain, tgpf->ob, brush);
 
 	tgpf->mat = ma;
 
+	/* check whether the material was newly added */
+	if (totcol != tgpf->ob->totcol) {
+		WM_event_add_notifier(C, NC_SPACE | ND_SPACE_PROPERTIES, NULL);
+	}
+
 	/* init undo */
 	gpencil_undo_init(tgpf->gpd);
 
diff --git a/source/blender/editors/gpencil/gpencil_old.c b/source/blender/editors/gpencil/gpencil_old.c
index 5d6abb594ce..47654b69da4 100644
--- a/source/blender/editors/gpencil/gpencil_old.c
+++ b/source/blender/editors/gpencil/gpencil_old.c
@@ -112,9 +112,7 @@ static int gpencil_convert_old_files_exec(bContext *C, wmOperator *UNUSED(op))
 			for (bGPDpalettecolor *palcolor = palette->colors.first; palcolor; palcolor = palcolor->next) {
 
 				/* create material slot */
-				BKE_object_material_slot_add(bmain, ob);
-				Material *ma = BKE_material_add_gpencil(bmain, palcolor->info);
-				assign_material(bmain, ob, ma, ob->totcol, BKE_MAT_ASSIGN_USERPREF);
+				Material *ma = BKE_gpencil_handle_new_material(bmain, ob, palcolor->info, NULL);
 
 				/* copy color settings */
 				MaterialGPencilStyle *gp_style = ma->gp_style;
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index dd949b21743..cd17f7dc640 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -302,6 +302,12 @@ static bool gpencil_draw_poll(bContext *C)
 			return false;
 		}
 
+		ToolSettings *ts = CTX_data_scene(C)->toolsettings;
+		if (!ts->gp_paint->paint.brush) {
+			CTX_wm_operator_poll_msg_set(C, "Grease Pencil has no active paint tool");
+			return false;
+		}
+
 		return true;
 	}
 	else {
@@ -1217,7 +1223,7 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
 	}
 
 	/* Save material index */
-	gps->mat_nr = BKE_gpencil_get_material_index(p->ob, p->material) - 1;
+	gps->mat_nr = BKE_gpencil_get_material_index_for_brush(p->ob, p->brush);
 
 	/* calculate UVs along the stroke */
 	ED_gpencil_calc_stroke_uv(obact, gps);
@@ -1834,31 +1840,10 @@ static void gp_init_colors(tGPsdata *p)
 	bGPdata *gpd = p->gpd;
 	Brush *brush = p->brush;
 
-	Material *ma = NULL;
 	MaterialGPencilStyle *gp_style = NULL;
 
 	/* use brush material */
-	ma = BKE_gpencil_get_material_from_brush(brush);
-
-	/* if no brush defaults, get material and color info
-	 * NOTE: Ensures that everything we need will exist...
-	 */
-	if ((ma == NULL) || (ma->gp_style == NULL)) {
-		BKE_gpencil_material_ensure(p->bmain, p->ob);
-
-		/* assign always the first material to the brush */
-		p->material = give_current_material(p->ob, 1);
-		brush->gpencil_settings->material = p->material;
-	}
-	else {
-		p->material = ma;
-	}
-
-	/* check if the material is already on object material slots and add it if missing */
-	if (BKE_gpencil_get_material_index(p->ob, p->material) == 0) {
-		BKE_object_material_slot_add(p->bmain, p->ob);
-		assign_material(p->bmain, p->ob, ma, p->ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-	}
+	p->material = BKE_gpencil_current_input_brush_material(p->bmain, p->ob, brush);
 
 	/* assign color information to temp tGPsdata */
 	gp_style = p->material->gp_style;
@@ -1996,7 +1981,14 @@ static bool gp_session_initdata(bContext *C, wmOperator *op, tGPsdata *p)
 		/* NOTE: This is only done for 3D view, as Materials aren't used for
 		 *       annotations in 2D editors
 		 */
+		int totcol = p->ob->totcol;
+
 		gp_init_colors(p);
+
+		/* check whether the material was newly added */
+		if (totcol != p->ob->totcol) {
+			WM_event_add_notifier(C, NC_SPACE | ND_SPACE_PROPERTIES, NULL);
+		}
 	}
 
 	/* lock axis (in some modes, disable) */
diff --git a/source/blender/editors/gpencil/gpencil_primitive.c b/source/blender/editors/gpencil/gpencil_primitive.c
index 9c4836c5d33..ddfbbded64b 100644
--- a/source/blender/editors/gpencil/gpencil_primitive.c
+++ b/source/blender/editors/gpencil/gpencil_primitive.c
@@ -137,29 +137,10 @@ static void gp_init_colors(tGPDprimitive *p)
 	bGPdata *gpd = p->gpd;
 	Brush *brush = p->brush;
 
-	Material *ma = NULL;
 	MaterialGPencilStyle *gp_style = NULL;
 
 	/* use brush material */
-	ma = BKE_gpencil_get_material_from_brush(brush);
-
-	/* if no brush defaults, get material and color info */
-	if ((ma == NULL) || (ma->gp_style == NULL)) {
-		BKE_gpencil_material_ensure(p->bmain, p->ob);
-
-		/* assign always the first material to the brush */
-		p->mat = give_current_material(p->ob, 1);
-		brush->gpencil_settings->material = p->mat;
-	}
-	else {
-		p->mat = ma;
-	}
-
-	/* check if the material is already on object material slots and add it if missing */
-	if (BKE_gpencil_get_material_index(p->ob, p->mat) == 0) {
-		BKE_object_material_slot_add(p->bmain, p->ob);
-		assign_material(p->bmain, p->ob, ma, p->ob->totcol, BKE_MAT_ASSIGN_USERPREF);
-	}
+	p->mat = BKE_gpencil_current_input_brush_material(p->bmain,p->ob, brush);
 
 	/* assign color information to temp data */
 	gp_style = p->mat->gp_style;
@@ -350,7 +331,7 @@ static void gp_primitive_set_initdata(bContext *C, tGPDprimitive *tgpi)
 
 	gps->flag |= GP_STROKE_3DSPACE;
 
-	gps->mat_nr = BKE_gpencil_get_material_index(tgpi->ob, tgpi->mat) - 1;
+	gps->mat_nr = BKE_gpencil_get_material_index(tgpi->ob, tgpi->mat);
 
 	/* allocate memory for storage points, but keep empty */
 	gps->totpoints = 0;
@@ -1130,7 +1111,7 @@ static void gpencil_primitive_init(bContext *C, wmOperator *op)
 	tgpi->gpd->runtime.tot_cp_points = 0;
 
 	/* getcolor info */
-	tgpi->mat = BKE_gpencil_material_ensure(bmain, tgpi->ob);
+	tgpi->mat = BKE_gpencil_current_input_toolsettings_material(bmain, tgpi->ob, ts);
 
 	/* set parameters */
 	tgpi->type = RNA_enum_get(op->ptr, "type");
diff --git a/source/blender/editors/gpencil/gpencil_utils.c b/source/blender/editors/gpencil/gpencil_utils.c
index 79a92c5a8de..ab116f115cc 100644
--- a/source/blender/editors/gpencil/gpencil_utils.c
+++ b/source/blender/editors/gpencil/gpencil_utils.c
@@ -1341,17 +1341,6 @@ void ED_gpencil_add_defaults(bContext *C, Object *ob)
 	Main *bmain = CTX_data_main(C);
 	ToolSettings *ts = CTX_data_tool_settings(C);
 
-	/* first try to reuse default material */
-	if (ob->actcol > 0) {
-		Material *ma = give_current_material(ob, ob->actcol);
-		if ((ma) && (ma->gp_style == NULL)) {
-			BKE_material_init_gpencil_settings(ma);
-		}
-	}
-
-	/* ensure color exist */
-	BKE_gpencil_material_ensure(bmain, ob);
-
 	BKE_paint_ensure(ts, (Paint **)&ts->gp_paint);
 	Paint *paint = &ts->gp_paint->paint;
 	/* if not exist, create a new one */
@@ -1360,6 +1349,9 @@ void ED_gpencil_add_defaults(bContext *C, Object *ob)
 		BKE_brush_gpencil_presets(C);
 	}
 
+	/* ensure a color exists and is assigned to object */
+	BKE_gpencil_current_input_toolsettings_material(bmain, ob, ts);
+
 	/* ensure multiframe falloff curve */
 	if (ts->gp_sculpt.cur_falloff == NULL) {
 		ts->gp_sculpt.cur_falloff = curvemapping_add(1, 0.0f, 0.0f, 1.0f, 1.0f);
@@ -1728,30 +1720,27 @@ static void gp_brush_cursor_draw(bContext *C, int x, int y, void *customdata)
 		}
 
 		/* get current drawing color */
-		ma = BKE_gpencil_get_material_from_brush(brush);
-		if (ma == NULL) {
-			BKE_gpencil_material_ensure(bmain, ob);
-			/* assign the first material to the brush */
-			ma = give_current_material(ob, 1);
-			brush->gpencil_settings->material = ma;
-		}
-		gp_style = ma->gp_style;
-
-		/* after some testing, display the size of the brush is not practical because
-		 * is too disruptive and the size of cursor does not change with zoom factor.
-		 * The decision was to use a fix size, instead of brush->thickness value.
-		 */
-		if ((gp_style) && (GPENCIL_PAINT_MODE(gpd)) &&
-		    ((brush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE) == 0) &&
-		    ((brush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP) == 0) &&
-		    (brush->gpencil_tool == GPAINT_TOOL_DRAW))
-		{
-			radius = 2.0f;
-			copy_v3_v3(color, gp_style->stroke_rgba);
-		}
-		else {
-			radius = 5.0f;
-			copy_v3_v3(color, brush->add_col);
+		ma = BKE_gpencil_get_material_for_brush(ob, brush);
+
+		if (ma) {
+			gp_style = ma->gp_style;
+
+			/* after some testing, display the size of the brush is not practical because
+			 * is too disruptive and the size of cursor does not change with zoom factor.
+			 * The decision was to use a fix size, instead of brush->thickness value.
+			 */
+			if ((gp_style) && (GPENCIL_PAINT_MODE(gpd)) &&
+				((brush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE) == 0) &&
+				((brush->gpencil_settings->flag & GP_BRUSH_STABILIZE_MOUSE_TEMP) == 0) &&
+				(brush->gpencil_tool == GPAINT_TOOL_DRAW))
+			{
+				radius = 2.0f;
+				copy_v3_v3(color, gp_style->stroke_rgba);
+			}
+			else {
+				radius = 5.0f;
+				copy_v3_v3(color, brush->add_col);
+			}
 		}
 	}
 
diff --git a/source/blender/editors/render/render_shading.c b/source/blender/editors/render/render_shading.c
index 0d4a8b8a71f..d78f71bb976 100644
--- a/source/blender/editors/render/render_shading.c
+++ b/source/blender/editors/render/render_shading.c
@@ -559,11 +559,6 @@ static int new_material_exec(bContext *C, wmOperator *UNUSED(op))
 		Material *new_ma = NULL;
 		BKE_id_copy_ex(bmain, &ma->id, (ID **)&new_ma, LIB_ID_COPY_DEFAULT | LIB_ID_COPY_ACTIONS);
 		ma = new_ma;
-
-		if (ob != NULL && ob->type == OB_GPENCIL) {
-			BKE_brush_update_material(bmain, new_ma, NULL);
-		}
-
 	}
 	else {
 		const char *name = DATA_("Material");