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, 31 insertions, 0 deletions

diff --git a/source/blender/editors/space_buttons/buttons_context.c b/source/blender/editors/space_buttons/buttons_context.c
index 3efaff72637..13762b348c2 100644
--- a/source/blender/editors/space_buttons/buttons_context.c
+++ b/source/blender/editors/space_buttons/buttons_context.c
@@ -33,6 +33,7 @@
 
 #include "DNA_armature_types.h"
 #include "DNA_brush_types.h"
+#include "DNA_collection_types.h"
 #include "DNA_linestyle_types.h"
 #include "DNA_material_types.h"
 #include "DNA_node_types.h"
@@ -153,6 +154,29 @@ static bool buttons_context_path_world(ButsContextPath *path)
   return false;
 }
 
+static bool buttons_context_path_collection(ButsContextPath *path, wmWindow *window)
+{
+  PointerRNA *ptr = &path->ptr[path->len - 1];
+
+  /* if we already have a (pinned) collection, we're done */
+  if (RNA_struct_is_a(ptr->type, &RNA_Collection)) {
+    return true;
+  }
+  /* if we have a view layer, use the view layer's active collection */
+  if (buttons_context_path_view_layer(path, window)) {
+    ViewLayer *view_layer = path->ptr[path->len - 1].data;
+    Collection *c = view_layer->active_collection->collection;
+    if (c) {
+      RNA_id_pointer_create(&c->id, &path->ptr[path->len]);
+      path->len++;
+      return true;
+    }
+  }
+
+  /* no path to a collection possible */
+  return false;
+}
+
 static bool buttons_context_path_linestyle(ButsContextPath *path, wmWindow *window)
 {
   PointerRNA *ptr = &path->ptr[path->len - 1];
@@ -575,6 +599,9 @@ static bool buttons_context_path(
     case BCONTEXT_WORLD:
       found = buttons_context_path_world(path);
       break;
+    case BCONTEXT_COLLECTION: /* This is for Line Art collection flags */
+      found = buttons_context_path_collection(path, window);
+      break;
     case BCONTEXT_TOOL:
       found = true;
       break;
@@ -858,6 +885,10 @@ int /*eContextResult*/ buttons_context(const bContext *C,
     set_pointer_type(path, result, &RNA_World);
     return CTX_RESULT_OK;
   }
+  if (CTX_data_equals(member, "collection")) {
+    set_pointer_type(path, result, &RNA_Collection);
+    return 1;
+  }
   if (CTX_data_equals(member, "object")) {
     set_pointer_type(path, result, &RNA_Object);
     return CTX_RESULT_OK;