[#7299] Orbit around selected causes panning to be reversed

The actual "bug" is much more general than simple viewmove. In fact, any time the center (for viewmove, or transform, or ...) on which initgrabz is called was behind the camera (in perspective, then), all mouse motion where reversed.

What I added is a special handling case that reverts those situation to the default case (center = viewport offset).

This changes the behavior for those case to something much more predictable/useable, but I doubt anyone expected it to work incorrectly, so I'd say that's alright.

This covers other cases than transform and viewmove (which are the only ones I really tested), but I don't expect breakage elsewhere.

If anyone disagrees with the change, feel free to offer a better solution.

1 files changed, 5 insertions, 0 deletions

diff --git a/source/blender/src/view.c b/source/blender/src/view.c
index c501dbb8f73..b17dfbd2bb7 100644
--- a/source/blender/src/view.c
+++ b/source/blender/src/view.c
@@ -152,6 +152,11 @@ void initgrabz(float x, float y, float z)
 	 * (accounting for near zero values)
 	 * */
 	if (G.vd->zfac < 1.e-6f && G.vd->zfac > -1.e-6f) G.vd->zfac = 1.0f;
+	
+	/* Negative zfac means x, y, z was behind the camera (in perspective).
+	 * This gives flipped directions, so revert back to ok default case.
+	 */
+	if (G.vd->zfac < 0.0f) G.vd->zfac = 1.0f;
 }
 
 void window_to_3d(float *vec, short mx, short my)