I’ve tried to bring this up before, but couldn’t get much purchase, so trying again.
Let’s do some exercises…
First, press numpad-1 to view a model from front view:
It seems to be okay, sort of. One subtlety though, it is nicely indicating the the Z-axis is going up. So add a unit to your model’s Z and he will go up in the viewport. Similarly add one unit to “X” and he will move right. However, it seems to indicate that the “Y” axis is facing the viewer. When in fact adding one to “Y” will move the monkey away. Let’s ignore that for now though…
Click on the “Y” in the center of the widget. It will do what you expect: you’ll be looking at the back of the monkey:
It still makes sense, a bit. The gizmo did change, but only indicating the reversal of the Y by dimming the ball. That doesn’t seem sufficient to me, but maybe enough for you. Again, let’s ignore that for now…
Instead, grab the “Y” ball in the middle and drag it just a bit, just enough to start moving, then move it back to where it was. You should still be looking at the back of his head because you made no change. But look at the widget now:
Yes, the “Y” ball is now bright green so it is indicating the the direction of the Y axis has reversed when it did not. Let’s examine this a bit further.
Drag the “Y” axis around a bit. Either drag by the bright green “Y” ball or the duller green ball. Try to put the dull green ball in front. Can you do it? Can you even tell if you’ve done so? Why is it a problem?
Compare this image of the gizmo to the one following. Here we are looking in front:
And this one is from behind. Yet the way that the “Y” axis balls are drawn is identical.
The problem is that the widget lives and works in a mini-3d environment, yet screws up some of the 3d cues your brain needs to judge it. If there are going to be big balls and small ones, then it is the ones in back that need to be small while the ones closer to us need to be larger. If there are going to be bright balls and dull balls, then the brights should be the ones that are in front.
This does mean that we need a new way to show the direction of the axis. So need to add “+” or “-” when needed. We don’t have to label every ball though. We can get away with labelling the closest 3 balls with direction and label, and not labelling the far balls, favoring the “+” axis when they are equal.