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, 15 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_collection_types.h b/source/blender/makesdna/DNA_collection_types.h
index 0a80e00d456..f5fcb0b190e 100644
--- a/source/blender/makesdna/DNA_collection_types.h
+++ b/source/blender/makesdna/DNA_collection_types.h
@@ -46,6 +46,14 @@ typedef struct CollectionChild {
   struct Collection *collection;
 } CollectionChild;
 
+enum CollectionFeatureLine_Usage {
+  COLLECTION_LRT_INCLUDE = 0,
+  COLLECTION_LRT_OCCLUSION_ONLY = (1 << 0),
+  COLLECTION_LRT_EXCLUDE = (1 << 1),
+  COLLECTION_LRT_INTERSECTION_ONLY = (1 << 2),
+  COLLECTION_LRT_NO_INTERSECTION = (1 << 3),
+};
+
 typedef struct Collection {
   ID id;
 
@@ -63,8 +71,10 @@ typedef struct Collection {
   /* Runtime-only, always cleared on file load. */
   short tag;
 
+  /** Line Art engine specific */
+  short lineart_usage;
+
   int16_t color_tag;
-  char _pad[2];
 
   /* Runtime. Cache of objects in this collection and all its
    * children. This is created on demand when e.g. some physics
@@ -72,6 +82,9 @@ typedef struct Collection {
    * collections due to memory usage reasons. */
   ListBase object_cache;
 
+  /* Need this for line art sub-collection selections. */
+  ListBase object_cache_instanced;
+
   /* Runtime. List of collections that are a parent of this
    * datablock. */
   ListBase parents;
@@ -89,6 +102,7 @@ enum {
   COLLECTION_RESTRICT_RENDER = (1 << 3),           /* Disable in renders. */
   COLLECTION_HAS_OBJECT_CACHE = (1 << 4),          /* Runtime: object_cache is populated. */
   COLLECTION_IS_MASTER = (1 << 5), /* Is master collection embedded in the scene. */
+  COLLECTION_HAS_OBJECT_CACHE_INSTANCED = (1 << 6), /* for object_cache_instanced. */
 };
 
 /* Collection->tag */