Rotating an anchor point

[Mark Spencer]

The anchor point doesn’t have any inherent rotation that affects the object – it is just the point in 3D space around which an object scales and rotates. To change an object’s rotational axes you use the HUD where you can choose the axes of the object itself, the axes of the world, or the axes of your current viewpoint.

—
Mark Spencer
Freelance Producer/Editor/Motion Graphics Artist
Apple-certified Master Trainer
Author, Motion 4 from Peachpit Press
https://www.applemotion.net

[David Cooper]

Hi Mark,

Thanks for responding. Perhaps I am missing something but, to test out your suggestion, I have added a shape (triangle) to the canvas, centred it and added a camera and switched the group to 3d to access the axis controls.

I can move the anchor point to a corner, rotate on z axis e.g. by -60º.
When set to ‘local axis’ – The anchor point and the control arrows rotate with the object but rotation of x and y does not match the direction the control arrows point in.
When set to either ‘world axis’ or ‘view axis’ the anchor point control arrows remain in their original position and the rotation on ‘x’ and ‘y’ rotates the object as the control arrows would imply.

I am intrigued / confused as to why when set to ‘local axis’ the shape does not move along the axis the control arrow implies. The limit of this means it is difficult, to say the least, to replicate this type of effect in motion as far as I can see.

Is this a limitation of motion or have I missed something entirely?

Thanks again

[David Cooper]

Writing my last elaboration gave me an idea and I have worked out what I was missing.

I was using the controls in the inspector to alter the x and y rotation and this only changes the object in relation to the canvas regardless of which axis you set. By switching to the 3d transform tool and using the rotation handles on x and y it achieves the desired effect (altering both x and y rotations in the inspector in relation to the canvas).

Thanks for the help.

[David Cooper]

I am returning to my experiments on this topic after sometime. Although I have, as yet, been unable to replicate the original effect.

I have realised a clearer way to describe the problem and am hoping someone can assist. I feel like I missing something obvious.

I am aware I can move the anchor point and this will effect the below but, assuming a central anchor point…

If I have a square or any object I can rotate this on…
the x axis – this rotates so the top moves towards the bottom
the y axis – this rotates so the left moves towards the right
the z axis – rotation around the anchor point moving the top left to top right, top right to top left etc.

The issue I am trying to solve is how to rotate to move a corner to a corner i.e. top left to bottom right.
(In my head this axis would be x=y)

Using the controls in the hud I can get close but the animation looks clunky as it is animating both the x and y axis simultaneously as opposed to a single clean axis.

Can this be achieved? It seems like a fairly basic feature… or perhaps I am being naive?