3D View: option only to show axis aligned image empties

Useful for using reference images that only make sense to see
in aligned axis-views.

This restores functionality possible with 2.7x background images.
See: T52668.

3 files changed, 18 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index 7ea395e9386..ed517bfc513 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -2985,6 +2985,15 @@ bool BKE_object_empty_image_data_is_visible_in_view3d(const Object *ob, const Re
     }
   }
 
+  if (visibility_flag & OB_EMPTY_IMAGE_HIDE_NON_AXIS_ALIGNED) {
+    float proj[3];
+    project_plane_v3_v3v3(proj, ob->obmat[2], rv3d->viewinv[2]);
+    const float proj_length_sq = len_squared_v3(proj);
+    if (proj_length_sq > 1e-5f) {
+      return false;
+    }
+  }
+
   return true;
 }
 
diff --git a/source/blender/makesdna/DNA_object_types.h b/source/blender/makesdna/DNA_object_types.h
index 613871b1fee..ff1839f997c 100644
--- a/source/blender/makesdna/DNA_object_types.h
+++ b/source/blender/makesdna/DNA_object_types.h
@@ -686,6 +686,7 @@ enum {
   OB_EMPTY_IMAGE_HIDE_ORTHOGRAPHIC = 1 << 1,
   OB_EMPTY_IMAGE_HIDE_BACK = 1 << 2,
   OB_EMPTY_IMAGE_HIDE_FRONT = 1 << 3,
+  OB_EMPTY_IMAGE_HIDE_NON_AXIS_ALIGNED = 1 << 4,
 };
 
 /** #Object.empty_image_flag */
diff --git a/source/blender/makesrna/intern/rna_object.c b/source/blender/makesrna/intern/rna_object.c
index 3c0fd282b17..c8a0d543b70 100644
--- a/source/blender/makesrna/intern/rna_object.c
+++ b/source/blender/makesrna/intern/rna_object.c
@@ -2821,6 +2821,14 @@ static void rna_def_object(BlenderRNA *brna)
       prop, "Display in Orthographic Mode", "Display image in orthographic mode");
   RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
 
+  prop = RNA_def_property(srna, "show_empty_image_only_axis_aligned", PROP_BOOLEAN, PROP_NONE);
+  RNA_def_property_boolean_sdna(
+      prop, NULL, "empty_image_visibility_flag", OB_EMPTY_IMAGE_HIDE_NON_AXIS_ALIGNED);
+  RNA_def_property_ui_text(prop,
+                           "Display Only Axis Aligned",
+                           "Only display the image when it is aligned with the view axis");
+  RNA_def_property_update(prop, NC_OBJECT | ND_DRAW, NULL);
+
   prop = RNA_def_property(srna, "use_empty_image_alpha", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_sdna(prop, NULL, "empty_image_flag", OB_EMPTY_IMAGE_USE_ALPHA_BLEND);
   RNA_def_property_ui_text(