Image Empties: More visibility settings

Support for showing images in background/foreground and only in perspective/orthographic view.

Internally the depth of the image is modified in the fragment shader by setting `gl_FragDepth` explicitly.

The UI still needs some work to improve usability, see D3863 for details.
Currently there is one duplicated function, not sure how to best deduplicate it yet. (`is_image_empty_visible`)

Reviewer: fclem, brecht, campbellbarton

Differential Revision: https://developer.blender.org/D3863

1 files changed, 15 insertions, 1 deletions

diff --git a/source/blender/editors/space_view3d/view3d_gizmo_empty.c b/source/blender/editors/space_view3d/view3d_gizmo_empty.c
index fe1129f8028..bc190355ea6 100644
--- a/source/blender/editors/space_view3d/view3d_gizmo_empty.c
+++ b/source/blender/editors/space_view3d/view3d_gizmo_empty.c
@@ -107,9 +107,21 @@ static void gizmo_empty_image_prop_matrix_set(
 	ob->ima_ofs[1] = (matrix[3][1] - (0.5f * dims[1])) / dims[1];
 }
 
+static bool is_image_empty_visible(Object *ob, RegionView3D *rv3d)
+{
+	int visibility_flag = ob->empty_image_visibility_flag;
+	if (rv3d->is_persp) {
+		return visibility_flag & OB_EMPTY_IMAGE_VISIBLE_PERSPECTIVE;
+	}
+	else {
+		return visibility_flag & OB_EMPTY_IMAGE_VISIBLE_ORTHOGRAPHIC;
+	}
+}
+
 static bool WIDGETGROUP_empty_image_poll(const bContext *C, wmGizmoGroupType *UNUSED(gzgt))
 {
 	View3D *v3d = CTX_wm_view3d(C);
+	RegionView3D *rv3d = CTX_wm_region_view3d(C);
 
 	if ((v3d->flag2 & V3D_RENDER_OVERRIDE) ||
 	    (v3d->gizmo_flag & (V3D_GIZMO_HIDE | V3D_GIZMO_HIDE_CONTEXT)))
@@ -120,7 +132,9 @@ static bool WIDGETGROUP_empty_image_poll(const bContext *C, wmGizmoGroupType *UN
 	Object *ob = CTX_data_active_object(C);
 
 	if (ob && ob->type == OB_EMPTY) {
-		return (ob->empty_drawtype == OB_EMPTY_IMAGE);
+		if (ob->empty_drawtype == OB_EMPTY_IMAGE){
+			return is_image_empty_visible(ob, rv3d);
+		}
 	}
 	return false;
 }