Grease Pencil: Add LineArt modifier

This adds the LineArt grease pencil modifier.

It takes objects or collections as input and generates various grease
pencil lines from these objects with the help of the active scene
camera. For example it can generate contour lines, intersection lines
and crease lines to name a few.

This is really useful as artists can then use 3D meshes to automatically
generate grease pencil lines for characters, enviroments or other
visualization purposes.

These lines can then be baked and edited as regular grease pencil lines.

Reviewed By: Sebastian Parborg, Antonio Vazquez, Matias Mendiola

Differential Revision: http://developer.blender.org/D8758

1 files changed, 81 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index a70b776b07a..8c12ccceb5d 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -36,6 +36,7 @@
 #include "DNA_shader_fx_types.h"
 #include "DNA_workspace_types.h"
 
+#include "BLI_math.h"
 #include "BLI_utildefines.h"
 
 #include "BLT_translation.h"
@@ -159,6 +160,21 @@ const EnumPropertyItem rna_enum_object_gpencil_type_items[] = {
     {GP_EMPTY, "EMPTY", ICON_EMPTY_AXIS, "Blank", "Create an empty grease pencil object"},
     {GP_STROKE, "STROKE", ICON_STROKE, "Stroke", "Create a simple stroke with basic colors"},
     {GP_MONKEY, "MONKEY", ICON_MONKEY, "Monkey", "Construct a Suzanne grease pencil object"},
+    {GP_LRT_SCENE,
+     "LRT_SCENE",
+     ICON_SCENE_DATA,
+     "Scene Line Art",
+     "Quickly set up Line Art for the whole scene"},
+    {GP_LRT_COLLECTION,
+     "LRT_COLLECTION",
+     ICON_OUTLINER_COLLECTION,
+     "Collection Line Art",
+     "Quickly set up Line Art for active collection"},
+    {GP_LRT_OBJECT,
+     "LRT_OBJECT",
+     ICON_CUBE,
+     "Object Line Art",
+     "Quickly set up Line Art for active collection"},
     {0, NULL, 0, NULL, NULL}};
 
 static const EnumPropertyItem parent_type_items[] = {
@@ -2083,6 +2099,12 @@ int rna_Object_use_dynamic_topology_sculpting_get(PointerRNA *ptr)
   return (ss && ss->bm);
 }
 
+static void rna_object_lineart_update(Main *UNUSED(bmain), Scene *UNUSED(scene), PointerRNA *ptr)
+{
+  DEG_id_tag_update(ptr->owner_id, ID_RECALC_GEOMETRY);
+  WM_main_add_notifier(NC_OBJECT | ND_MODIFIER, ptr->owner_id);
+}
+
 #else
 
 static void rna_def_vertex_group(BlenderRNA *brna)
@@ -2645,6 +2667,59 @@ static void rna_def_object_display(BlenderRNA *brna)
   RNA_define_lib_overridable(false);
 }
 
+static void rna_def_object_lineart(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  static EnumPropertyItem prop_feature_line_usage_items[] = {
+      {OBJECT_LRT_INHERENT,
+       "INHEREIT",
+       0,
+       "Inhereit",
+       "Follow settings from the parent collection"},
+      {OBJECT_LRT_INCLUDE, "INCLUDE", 0, "Include", "Include this object into LRT calculation"},
+      {OBJECT_LRT_OCCLUSION_ONLY,
+       "OCCLUSION_ONLY",
+       0,
+       "Occlusion Only",
+       "Don't produce lines, only used as occlusion object"},
+      {OBJECT_LRT_EXCLUDE, "EXCLUDE", 0, "Exclude", "Don't use this object for LRT rendering"},
+      {OBJECT_LRT_INTERSECTION_ONLY,
+       "INTERSECTION_ONLY",
+       0,
+       "Intersection Only",
+       "Only to generate intersection lines with this object"},
+      {OBJECT_LRT_NO_INTERSECTION,
+       "NO_INTERSECTION",
+       0,
+       "No Intersection",
+       "Include this object but do not generate intersection lines"},
+      {0, NULL, 0, NULL, NULL},
+  };
+
+  srna = RNA_def_struct(brna, "ObjectLineArt", NULL);
+  RNA_def_struct_ui_text(srna, "Object Line Art", "Object lineart settings");
+  RNA_def_struct_sdna(srna, "ObjectLineArt");
+
+  prop = RNA_def_property(srna, "usage", PROP_ENUM, PROP_NONE);
+  RNA_def_property_enum_items(prop, prop_feature_line_usage_items);
+  RNA_def_property_ui_text(prop, "Usage", "How to use this object in line art calculation");
+  RNA_def_property_update(prop, 0, "rna_object_lineart_update");
+
+  prop = RNA_def_property(srna, "use_crease_override", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(prop, NULL, "flags", OBJECT_LRT_OWN_CREASE);
+  RNA_def_property_ui_text(prop, "Own Crease", "Use own crease setting to overwrite scene global");
+  RNA_def_property_update(prop, 0, "rna_object_lineart_update");
+
+  prop = RNA_def_property(srna, "crease_threshold", PROP_FLOAT, PROP_ANGLE);
+  RNA_def_property_range(prop, 0, DEG2RAD(180.0f));
+  RNA_def_property_ui_range(prop, 0.0f, DEG2RAD(180.0f), 0.01f, 1);
+  RNA_def_property_ui_text(
+      prop, "Own Crease", "Angles smaller than this will be treated as creases");
+  RNA_def_property_update(prop, 0, "rna_object_lineart_update");
+}
+
 static void rna_def_object(BlenderRNA *brna)
 {
   StructRNA *srna;
@@ -3414,6 +3489,11 @@ static void rna_def_object(BlenderRNA *brna)
   RNA_def_property_pointer_funcs(prop, "rna_Object_display_get", NULL, NULL, NULL);
   RNA_def_property_ui_text(prop, "Object Display", "Object display settings for 3D viewport");
 
+  /* Line Art */
+  prop = RNA_def_property(srna, "lineart", PROP_POINTER, PROP_NONE);
+  RNA_def_property_struct_type(prop, "ObjectLineArt");
+  RNA_def_property_ui_text(prop, "Line Art", "Line Art settings for the object");
+
   RNA_define_lib_overridable(false);
 
   /* anim */
@@ -3434,6 +3514,7 @@ void RNA_def_object(BlenderRNA *brna)
   rna_def_face_map(brna);
   rna_def_material_slot(brna);
   rna_def_object_display(brna);
+  rna_def_object_lineart(brna);
   RNA_define_animate_sdna(true);
 }