[Bf-blender-cvs] [445433a6913] master: Fix empty object front/back display in perspective views

[Campbell Barton]

Commit: 445433a6913fb95fe04bf69089710cab877a581b
Author: Campbell Barton
Date:   Tue Feb 5 10:39:43 2019 +1100
Branches: master
https://developer.blender.org/rB445433a6913fb95fe04bf69089710cab877a581b

Fix empty object front/back display in perspective views

===================================================================

M	source/blender/blenkernel/intern/object.c

===================================================================

diff --git a/source/blender/blenkernel/intern/object.c b/source/blender/blenkernel/intern/object.c
index d8bc27fa596..5cb68a7e5bb 100644
--- a/source/blender/blenkernel/intern/object.c
+++ b/source/blender/blenkernel/intern/object.c
@@ -2608,9 +2608,20 @@ bool BKE_object_empty_image_is_visible_in_view3d(const Object *ob, const RegionV
 	char visibility_flag = ob->empty_image_visibility_flag;
 
 	if ((visibility_flag & (OB_EMPTY_IMAGE_HIDE_BACK | OB_EMPTY_IMAGE_HIDE_FRONT)) != 0) {
-		const float eps = 1e-5f;
-		/* TODO: this isn't correct with perspective projection. */
-		const float dot = dot_v3v3((float *)&ob->obmat[2], (float *)&rv3d->viewinv[2]);
+		float eps, dot;
+		if (rv3d->is_persp) {
+			/* Note, we could normalize the 'view_dir' then use 'eps'
+			 * however the issue with empty objects being visible when viewed from the side
+			 * is only noticeable in orthographic views. */
+			float view_dir[3];
+			sub_v3_v3v3(view_dir, rv3d->viewinv[3], ob->obmat[3]);
+			dot = dot_v3v3(ob->obmat[2], view_dir);
+			eps = 0.0f;
+		}
+		else {
+			dot = dot_v3v3(ob->obmat[2], rv3d->viewinv[2]);
+			eps = 1e-5f;
+		}
 		if (visibility_flag & OB_EMPTY_IMAGE_HIDE_BACK) {
 			if (dot < eps) {
 				return false;