GPv3: Add view layer name property

This adds the `viewlayername` property to grease pencil v3 layers.
It's exposed as `viewlayer_render` in python.

Note: this is not used in the renderer yet. Will be used in a following PR.
Pull Request: https://projects.blender.org/blender/blender/pulls/119422

scripts/startup/bl_ui/properties_data_grease_pencil.py

@@ -149,6 +149,9 @@ class DATA_PT_grease_pencil_layer_relations(LayerDataButtonsPanel, Panel):
         col = layout.row(align=True)
         col.prop(layer, "pass_index")
 
+        col = layout.row(align=True)
+        col.prop_search(layer, "viewlayer_render", context.scene, "view_layers", text="View Layer")
+
 
 class DATA_PT_grease_pencil_custom_props(DataButtonsPanel, PropertyPanel, Panel):
     _context_path = "object.data"

source/blender/blenkernel/BKE_grease_pencil.hh

@@ -456,6 +456,13 @@ class Layer : public ::GreasePencilLayer {
   StringRefNull parent_bone_name() const;
   void set_parent_bone_name(const char *new_name);
 
+  /**
+   * Returns the view layer name that this layer should be rendered in or an empty
+   * `StringRefNull` if no such name is set.
+   */
+  StringRefNull view_layer_name() const;
+  void set_view_layer_name(const char *new_name);
+
  private:
   using SortedKeysIterator = const int *;
 

source/blender/blenkernel/intern/grease_pencil.cc

@@ -672,6 +672,8 @@ Layer::Layer()
   zero_v3(this->rotation);
   copy_v3_fl(this->scale, 1.0f);
 
+  this->viewlayername = nullptr;
+
   BLI_listbase_clear(&this->masks);
 
   this->runtime = MEM_new<LayerRuntime>(__func__);
@@ -698,6 +700,8 @@ Layer::Layer(const Layer &other) : Layer()
   copy_v3_v3(this->rotation, other.rotation);
   copy_v3_v3(this->scale, other.scale);
 
+  this->set_view_layer_name(other.viewlayername);
+
   /* Note: We do not duplicate the frame storage since it is only needed for writing to file. */
   this->runtime->frames_ = other.runtime->frames_;
   this->runtime->sorted_keys_cache_ = other.runtime->sorted_keys_cache_;
@@ -720,6 +724,7 @@ Layer::~Layer()
   }
 
   MEM_SAFE_FREE(this->parsubstr);
+  MEM_SAFE_FREE(this->viewlayername);
 
   MEM_delete(this->runtime);
   this->runtime = nullptr;
@@ -1015,6 +1020,19 @@ float4x4 Layer::local_transform() const
       float3(this->translation), float3(this->rotation), float3(this->scale));
 }
 
+StringRefNull Layer::view_layer_name() const
+{
+  return (this->viewlayername != nullptr) ? StringRefNull(this->viewlayername) : StringRefNull();
+}
+
+void Layer::set_view_layer_name(const char *new_name)
+{
+  if (this->viewlayername != nullptr) {
+    MEM_freeN(this->viewlayername);
+  }
+  this->viewlayername = BLI_strdup_null(new_name);
+}
+
 LayerGroup::LayerGroup()
 {
   new (&this->base) TreeNode(GP_LAYER_TREE_GROUP);
@@ -2680,6 +2698,7 @@ static void read_layer(BlendDataReader *reader,
   BLO_read_data_address(reader, &node->base.name);
   node->base.parent = parent;
   BLO_read_data_address(reader, &node->parsubstr);
+  BLO_read_data_address(reader, &node->viewlayername);
 
   /* Read frames storage. */
   BLO_read_int32_array(reader, node->frames_storage.num, &node->frames_storage.keys);
@@ -2748,6 +2767,7 @@ static void write_layer(BlendWriter *writer, GreasePencilLayer *node)
   BLO_write_struct(writer, GreasePencilLayer, node);
   BLO_write_string(writer, node->base.name);
   BLO_write_string(writer, node->parsubstr);
+  BLO_write_string(writer, node->viewlayername);
 
   BLO_write_int32_array(writer, node->frames_storage.num, node->frames_storage.keys);
   BLO_write_struct_array(

source/blender/blenkernel/intern/grease_pencil_convert_legacy.cc

@@ -436,6 +436,8 @@ void legacy_gpencil_to_grease_pencil(Main &bmain, GreasePencil &grease_pencil, b
     copy_v3_v3(new_layer.rotation, gpl->rotation);
     copy_v3_v3(new_layer.scale, gpl->scale);
 
+    new_layer.set_view_layer_name(gpl->viewlayername);
+
     /* Convert the layer masks. */
     LISTBASE_FOREACH (bGPDlayer_Mask *, mask, &gpl->mask_layers) {
       LayerMask *new_mask = MEM_new<LayerMask>(mask->name);

source/blender/makesdna/DNA_grease_pencil_types.h

@@ -303,6 +303,8 @@ typedef struct GreasePencilLayer {
    */
   float translation[3], rotation[3], scale[3];
   char _pad2[4];
+  /** Name of the view layer used to filter render output. */
+  char *viewlayername;
   /**
    * Runtime struct pointer.
    */

source/blender/makesrna/intern/rna_grease_pencil.cc

@@ -325,6 +325,13 @@ static void rna_def_grease_pencil_layer(BlenderRNA *brna)
   RNA_def_property_ui_range(prop, -FLT_MAX, FLT_MAX, 1, 3);
   RNA_def_property_ui_text(prop, "Scale", "Scale of the layer");
   RNA_def_property_update(prop, NC_GPENCIL | ND_DATA, "rna_grease_pencil_update");
+
+  prop = RNA_def_property(srna, "viewlayer_render", PROP_STRING, PROP_NONE);
+  RNA_def_property_string_sdna(prop, nullptr, "viewlayername");
+  RNA_def_property_ui_text(
+      prop,
+      "ViewLayer",
+      "Only include Layer in this View Layer render output (leave blank to include always)");
 }
 
 static void rna_def_grease_pencil_layers_api(BlenderRNA *brna, PropertyRNA *cprop)