5 files changed, 98 insertions, 11 deletions

diff --git a/source/blender/blenkernel/intern/brush.cc b/source/blender/blenkernel/intern/brush.cc
index fc45ce0bbe7..34b87dda338 100644
--- a/source/blender/blenkernel/intern/brush.cc
+++ b/source/blender/blenkernel/intern/brush.cc
@@ -186,6 +186,7 @@ static void brush_foreach_id(ID *id, LibraryForeachIDData *data)
   BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, brush->paint_curve, IDWALK_CB_USER);
   if (brush->gpencil_settings) {
     BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, brush->gpencil_settings->material, IDWALK_CB_USER);
+    BKE_LIB_FOREACHID_PROCESS_IDSUPER(data, brush->gpencil_settings->material_alt, IDWALK_CB_USER);
   }
   BKE_LIB_FOREACHID_PROCESS_FUNCTION_CALL(data, BKE_texture_mtex_foreach_id(data, &brush->mtex));
   BKE_LIB_FOREACHID_PROCESS_FUNCTION_CALL(data,
@@ -346,6 +347,7 @@ static void brush_blend_read_lib(BlendLibReader *reader, ID *id)
     else {
       brush->gpencil_settings->material = nullptr;
     }
+    BLO_read_id_address(reader, brush->id.lib, &brush->gpencil_settings->material_alt);
   }
 }
 
@@ -358,6 +360,7 @@ static void brush_blend_read_expand(BlendExpander *expander, ID *id)
   BLO_expand(expander, brush->paint_curve);
   if (brush->gpencil_settings != nullptr) {
     BLO_expand(expander, brush->gpencil_settings->material);
+    BLO_expand(expander, brush->gpencil_settings->material_alt);
   }
 }
 
@@ -704,6 +707,7 @@ void BKE_gpencil_brush_preset_set(Main *bmain, Brush *brush, const short type)
   /* Set vertex mix factor. */
   brush->gpencil_settings->vertex_mode = GPPAINT_MODE_BOTH;
   brush->gpencil_settings->vertex_factor = 1.0f;
+  brush->gpencil_settings->material_alt = nullptr;
 
   switch (type) {
     case GP_BRUSH_PRESET_AIRBRUSH: {
diff --git a/source/blender/editors/gpencil/gpencil_paint.c b/source/blender/editors/gpencil/gpencil_paint.c
index 50651e1919a..7f11ff7ebd5 100644
--- a/source/blender/editors/gpencil/gpencil_paint.c
+++ b/source/blender/editors/gpencil/gpencil_paint.c
@@ -918,6 +918,64 @@ static void gpencil_stroke_unselect(bGPdata *gpd, bGPDstroke *gps)
   }
 }
 
+static bGPDstroke *gpencil_stroke_to_outline(tGPsdata *p, bGPDstroke *gps)
+{
+  bGPDlayer *gpl = p->gpl;
+  RegionView3D *rv3d = p->region->regiondata;
+  Brush *brush = p->brush;
+  BrushGpencilSettings *gpencil_settings = brush->gpencil_settings;
+  MaterialGPencilStyle *gp_style = BKE_gpencil_material_settings(p->ob, gps->mat_nr + 1);
+  const bool is_stroke = ((gp_style->flag & GP_MATERIAL_STROKE_SHOW) != 0);
+
+  if (!is_stroke) {
+    return gps;
+  }
+
+  /* Duplicate the stroke to apply any layer thickness change. */
+  bGPDstroke *gps_duplicate = BKE_gpencil_stroke_duplicate(gps, true, false);
+
+  /* Apply layer thickness change. */
+  gps_duplicate->thickness += gpl->line_change;
+  /* Apply object scale to thickness. */
+  gps_duplicate->thickness *= mat4_to_scale(p->ob->obmat);
+  CLAMP_MIN(gps_duplicate->thickness, 1.0f);
+
+  /* Stroke. */
+  float diff_mat[4][4];
+  unit_m4(diff_mat);
+  bGPDstroke *gps_perimeter = BKE_gpencil_stroke_perimeter_from_view(
+      rv3d, p->gpd, gpl, gps_duplicate, 3, diff_mat);
+  /* Assign material. */
+  if (gpencil_settings->material_alt == NULL) {
+    gps_perimeter->mat_nr = gps->mat_nr;
+  }
+  else {
+    Material *ma = gpencil_settings->material_alt;
+    int mat_idx = BKE_gpencil_material_find_index_by_name_prefix(p->ob, ma->id.name + 2);
+    if (mat_idx > -1) {
+      gps_perimeter->mat_nr = mat_idx;
+    }
+    else {
+      gps_perimeter->mat_nr = gps->mat_nr;
+    }
+  }
+
+  /* Set pressure constant. */
+  bGPDspoint *pt;
+  for (int i = 0; i < gps_perimeter->totpoints; i++) {
+    pt = &gps_perimeter->points[i];
+    pt->pressure = 1.0f;
+  }
+
+  /* Remove original stroke. */
+  BKE_gpencil_free_stroke(gps);
+
+  /* Free Temp stroke. */
+  BKE_gpencil_free_stroke(gps_duplicate);
+
+  return gps_perimeter;
+}
+
 /* make a new stroke from the buffer data */
 static void gpencil_stroke_newfrombuffer(tGPsdata *p)
 {
@@ -1221,6 +1279,23 @@ static void gpencil_stroke_newfrombuffer(tGPsdata *p)
       BKE_gpencil_stroke_simplify_adaptive(gpd, gps, brush->gpencil_settings->simplify_f);
     }
 
+    /* Set material index. */
+    gps->mat_nr = BKE_gpencil_object_material_get_index_from_brush(p->ob, p->brush);
+    if (gps->mat_nr < 0) {
+      if (p->ob->actcol - 1 < 0) {
+        gps->mat_nr = 0;
+      }
+      else {
+        gps->mat_nr = p->ob->actcol - 1;
+      }
+    }
+
+    /* Convert to Outline. */
+    if ((brush->gpencil_settings->flag & GP_BRUSH_GROUP_SETTINGS) &&
+        (brush->gpencil_settings->flag & GP_BRUSH_OUTLINE_STROKE)) {
+      gps = gpencil_stroke_to_outline(p, gps);
+    }
+
     /* reproject to plane (only in 3d space) */
     gpencil_reproject_toplane(p, gps);
     /* change position relative to parent object */
@@ -1235,17 +1310,6 @@ static void gpencil_stroke_newfrombuffer(tGPsdata *p)
     }
   }
 
-  /* Save material index */
-  gps->mat_nr = BKE_gpencil_object_material_get_index_from_brush(p->ob, p->brush);
-  if (gps->mat_nr < 0) {
-    if (p->ob->actcol - 1 < 0) {
-      gps->mat_nr = 0;
-    }
-    else {
-      gps->mat_nr = p->ob->actcol - 1;
-    }
-  }
-
   /* add stroke to frame, usually on tail of the listbase, but if on back is enabled the stroke
    * is added on listbase head because the drawing order is inverse and the head stroke is the
    * first to draw. This is very useful for artist when drawing the background.
diff --git a/source/blender/makesdna/DNA_brush_enums.h b/source/blender/makesdna/DNA_brush_enums.h
index adda23c26f2..988853e6694 100644
--- a/source/blender/makesdna/DNA_brush_enums.h
+++ b/source/blender/makesdna/DNA_brush_enums.h
@@ -87,6 +87,8 @@ typedef enum eGPDbrush_Flag {
   GP_BRUSH_OCCLUDE_ERASER = (1 << 15),
   /* Post process trim stroke */
   GP_BRUSH_TRIM_STROKE = (1 << 16),
+  /* Post process convert to outline stroke */
+  GP_BRUSH_OUTLINE_STROKE = (1 << 17),
 } eGPDbrush_Flag;
 
 typedef enum eGPDbrush_Flag2 {
diff --git a/source/blender/makesdna/DNA_brush_types.h b/source/blender/makesdna/DNA_brush_types.h
index b24bb786593..174ec614238 100644
--- a/source/blender/makesdna/DNA_brush_types.h
+++ b/source/blender/makesdna/DNA_brush_types.h
@@ -135,6 +135,8 @@ typedef struct BrushGpencilSettings {
   /* optional link of material to replace default in context */
   /** Material. */
   struct Material *material;
+  /** Material Alternative for secondary operations. */
+  struct Material *material_alt;
 } BrushGpencilSettings;
 
 typedef struct BrushCurvesSculptSettings {
diff --git a/source/blender/makesrna/intern/rna_brush.c b/source/blender/makesrna/intern/rna_brush.c
index 82eb390df52..40038921573 100644
--- a/source/blender/makesrna/intern/rna_brush.c
+++ b/source/blender/makesrna/intern/rna_brush.c
@@ -1820,6 +1820,12 @@ static void rna_def_gpencil_options(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Trim Stroke Ends", "Trim intersecting stroke ends");
   RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
 
+  prop = RNA_def_property(srna, "use_settings_outline", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flag", GP_BRUSH_OUTLINE_STROKE);
+  RNA_def_property_boolean_default(prop, false);
+  RNA_def_property_ui_text(prop, "Outline", "Convert stroke to perimeter");
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+
   prop = RNA_def_property(srna, "direction", PROP_ENUM, PROP_NONE);
   RNA_def_property_enum_bitflag_sdna(prop, NULL, "sculpt_flag");
   RNA_def_property_enum_items(prop, prop_direction_items);
@@ -1883,6 +1889,15 @@ static void rna_def_gpencil_options(BlenderRNA *brna)
   RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
   RNA_def_property_update(prop, NC_GPENCIL | ND_DATA, "rna_Brush_material_update");
 
+  /* Secondary Material */
+  prop = RNA_def_property(srna, "material_alt", PROP_POINTER, PROP_NONE);
+  RNA_def_property_struct_type(prop, "Material");
+  RNA_def_property_pointer_funcs(prop, NULL, NULL, NULL, "rna_BrushGpencilSettings_material_poll");
+  RNA_def_property_flag(prop, PROP_EDITABLE | PROP_ID_SELF_CHECK | PROP_CONTEXT_UPDATE);
+  RNA_def_property_ui_text(prop, "Material", "Material used for secondary uses for this brush");
+  RNA_def_property_clear_flag(prop, PROP_ANIMATABLE);
+  RNA_def_property_update(prop, NC_GPENCIL | ND_DATA, "rna_Brush_material_update");
+
   prop = RNA_def_property(srna, "show_fill_boundary", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "flag", GP_BRUSH_FILL_SHOW_HELPLINES);
   RNA_def_property_boolean_default(prop, true);