GPencil: Asset Manager support (LITE)

This patch replaces D13193 and remove any transform tool in the import. Now the import must be done in Edit mode and
all transformations must be done with the standard transform tools of Blender.

A new operator has been added to create an asset base on one of the next option:

* Active Layer.
* All Layers.
* All Layers Separated
* Active Frame (Active Layer).
* Active Frame (All Layers).
* Selected Frames.
* Selected Strokes.

The menu uses `Create Asset`instead of `Mark Asset` because the asset is created as new datablock and not reuse existing data.

To import asset, set the grease pencil object where you want import in Edit mode.

Also new asset preview for Grease Pencil has been added.

For testing, be sure to enable `Experimental Feature`and `Developers Extra`

Differential Revision: https://developer.blender.org/D15271

1 files changed, 122 insertions, 1 deletions

diff --git a/source/blender/editors/render/render_preview.cc b/source/blender/editors/render/render_preview.cc
index addcedc4481..bb067d57649 100644
--- a/source/blender/editors/render/render_preview.cc
+++ b/source/blender/editors/render/render_preview.cc
@@ -30,6 +30,7 @@
 #include "DNA_brush_types.h"
 #include "DNA_camera_types.h"
 #include "DNA_collection_types.h"
+#include "DNA_gpencil_types.h"
 #include "DNA_light_types.h"
 #include "DNA_material_types.h"
 #include "DNA_mesh_types.h"
@@ -47,6 +48,7 @@
 #include "BKE_colortools.h"
 #include "BKE_context.h"
 #include "BKE_global.h"
+#include "BKE_gpencil.h"
 #include "BKE_icons.h"
 #include "BKE_idprop.h"
 #include "BKE_image.h"
@@ -365,6 +367,7 @@ static ID *duplicate_ids(ID *id, const bool allow_failure)
     case ID_MA:
     case ID_TE:
     case ID_LA:
+    case ID_GD:
     case ID_WO: {
       BLI_assert(BKE_previewimg_id_supports_jobs(id));
       ID *id_copy = BKE_id_copy_ex(nullptr,
@@ -763,6 +766,8 @@ struct ObjectPreviewData {
   /* Copy of the object to create the preview for. The copy is for thread safety (and to insert
    * it into its own main). */
   Object *object;
+  /* Datablock copy. Can be nullptr. */
+  ID *datablock;
   /* Current frame. */
   int cfra;
   int sizex;
@@ -851,7 +856,7 @@ static void object_preview_render(IconPreview *preview, IconPreviewSize *preview
   preview_data.pr_main = preview_main;
   /* Act on a copy. */
   preview_data.object = (Object *)preview->id_copy;
-  preview_data.cfra = preview->scene->r.cfra;
+  preview_data.datablock = nullptr;
   preview_data.sizex = preview_sized->sizex;
   preview_data.sizey = preview_sized->sizey;
 
@@ -1031,6 +1036,119 @@ static void action_preview_render(IconPreview *preview, IconPreviewSize *preview
 /** \} */
 
 /* -------------------------------------------------------------------- */
+/** \name Grease Pencil Preview
+ * \{ */
+
+static Scene *gpencil_preview_scene_create(const struct ObjectPreviewData *preview_data,
+                                           Depsgraph **r_depsgraph)
+{
+  Scene *scene = BKE_scene_add(preview_data->pr_main, "Object preview scene");
+  /* Grease pencil needs to set the scene to the current frame or the strokes
+   * will not be visible in the preview.  */
+  CFRA = preview_data->cfra;
+  ViewLayer *view_layer = (ViewLayer *)scene->view_layers.first;
+  Depsgraph *depsgraph = DEG_graph_new(
+      preview_data->pr_main, scene, view_layer, DAG_EVAL_VIEWPORT);
+
+  /* Grease pencil draw engine needs an object to draw the datablock. */
+  Object *ob_temp = BKE_object_add_for_data(preview_data->pr_main,
+                                            view_layer,
+                                            OB_GPENCIL,
+                                            "preview_object",
+                                            preview_data->datablock,
+                                            true);
+  BLI_assert(ob_temp != nullptr);
+  /* Copy the materials to get full color previews. */
+  const short *materials_len_p = BKE_id_material_len_p(preview_data->datablock);
+  if (materials_len_p && *materials_len_p > 0) {
+    BKE_object_materials_test(preview_data->pr_main, ob_temp, preview_data->datablock);
+  }
+
+  Object *camera_object = object_preview_camera_create(preview_data->pr_main, view_layer, ob_temp);
+
+  scene->camera = camera_object;
+  scene->r.xsch = preview_data->sizex;
+  scene->r.ysch = preview_data->sizey;
+  scene->r.size = 100;
+
+  Base *preview_base = BKE_view_layer_base_find(view_layer, ob_temp);
+  /* For 'view selected' below. */
+  preview_base->flag |= BASE_SELECTED;
+
+  DEG_graph_build_from_view_layer(depsgraph);
+  DEG_evaluate_on_refresh(depsgraph);
+
+  ED_view3d_camera_to_view_selected(preview_data->pr_main, depsgraph, scene, camera_object);
+
+  BKE_scene_graph_update_tagged(depsgraph, preview_data->pr_main);
+
+  *r_depsgraph = depsgraph;
+  return scene;
+}
+
+/* Render a grease pencil datablock. As the Draw Engine needs an object, the datablock is assigned
+ * to a temporary object, just for render. */
+static void gpencil_preview_render(IconPreview *preview, IconPreviewSize *preview_sized)
+{
+  Main *preview_main = BKE_main_new();
+  const float pixelsize_old = U.pixelsize;
+  char err_out[256] = "unknown";
+
+  BLI_assert(preview->id_copy && (preview->id_copy != preview->id));
+
+  /* Find the frame number to make preview visible. */
+  int f_min, f_max;
+  bGPdata *gpd = (bGPdata *)preview->id_copy;
+  BKE_gpencil_frame_min_max(gpd, &f_min, &f_max);
+  const int framenum = ((preview->scene->r.cfra < f_min) || (preview->scene->r.cfra > f_max)) ?
+                           f_min :
+                           preview->scene->r.cfra;
+
+  struct ObjectPreviewData preview_data = {};
+  preview_data.pr_main = preview_main;
+  /* Act on a copy. */
+  preview_data.object = nullptr;
+  preview_data.datablock = (ID *)preview->id_copy;
+  preview_data.cfra = framenum;
+  preview_data.sizex = preview_sized->sizex;
+  preview_data.sizey = preview_sized->sizey;
+
+  Depsgraph *depsgraph;
+  Scene *scene = gpencil_preview_scene_create(&preview_data, &depsgraph);
+
+  U.pixelsize = 2.0f;
+
+  View3DShading shading;
+  BKE_screen_view3d_shading_init(&shading);
+
+  ImBuf *ibuf = ED_view3d_draw_offscreen_imbuf_simple(
+      depsgraph,
+      DEG_get_evaluated_scene(depsgraph),
+      &shading,
+      OB_TEXTURE,
+      DEG_get_evaluated_object(depsgraph, scene->camera),
+      preview_sized->sizex,
+      preview_sized->sizey,
+      IB_rect,
+      V3D_OFSDRAW_OVERRIDE_SCENE_SETTINGS,
+      R_ALPHAPREMUL,
+      nullptr,
+      nullptr,
+      err_out);
+
+  U.pixelsize = pixelsize_old;
+
+  if (ibuf) {
+    icon_copy_rect(ibuf, preview_sized->sizex, preview_sized->sizey, preview_sized->rect);
+    IMB_freeImBuf(ibuf);
+  }
+
+  DEG_graph_free(depsgraph);
+  BKE_main_free(preview_main);
+}
+/** \} */
+
+/* -------------------------------------------------------------------- */
 /** \name New Shader Preview System
  * \{ */
 
@@ -1634,6 +1752,9 @@ static void icon_preview_startjob_all_sizes(void *customdata,
         case ID_AC:
           action_preview_render(ip, cur_size);
           continue;
+        case ID_GD:
+          gpencil_preview_render(ip, cur_size);
+          continue;
         default:
           /* Fall through to the same code as the `ip->id == nullptr` case. */
           break;