Perhaps I’m daft but i see this thrown around a lot in tutorials without explaining why it’s used or when it should be used.
Can someone clear this up for ol’ dumdum me?
because you want to un-rotate [alt+r] an object [perhaps to get a cube back going with a grid, so you can edit it easily] or make it’s current position the non-rotated one [apply deformation]
Every object has its own set of local xyz axes, while the “world” has its own fixed global axes. Local axes can be rotated with an object. Both of these commands re-orient object’s local axes to be parallel with the world.
Clear Rotation reorients the local axis, and the object mesh goes with it (the “top” of the object points up in the world again).
Apply Rotation reorients only the local axis; the mesh stays where it is (a different face of the object is now its “top”).
Edit: Yeah, what z3r0d said!
Thank you for the responses.
Now that clears up the Why’s.
How about the When’s. Could you provide examples of when you would use this pretty much as a rule? i.e. while building armatures, etc?
when building your armature, you may want to test out the movements, and then clear them as you adjust contraints, limits etc etc, indespensible.
ALT-R,ALT-S ALT-G.
Also should be a regular practice when making objects follow paths, so they point the direction you want. See Greybeard’s excellent video tutorial on paths:
Take an eye for example. The standard method of adding an eye requires that its polar region faces forward rather than upward so we can colour it (or cut it out) and make an iris and pupil.
This means rotating a sphere 90deg to the front. When you then try and maipulate that sphere using IPO curves you have to remember it’s not properly aligned any more because the Y-axis is now up/down and Z-axis is front/back. We don’t want that - we usually want Z to be up and down to maintain our sanity.
So you “apply” rotation and the sphere now has Z-axis up but the polar circle is still facing forward so we can make an iris and pupil out of it. So what we’ve effectively achieved is we’ve rotated all the vertices by 90deg forward but we haven’t rotated the “object”. Knowing this you might realise the same thing could be achieved by rotating all verts in Edit Mode.
One major area where I use Alt-R (remove rotations) is when playing with an armature. After a while you lose track of just how much a bone has been rotated in various directions and the mesh might even start to look a bit weary and twisted at joints. Alt-R puts the bone back to its original rotation and clears up any mess that’s crept in during posing.