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Question

Auto-Orient

Forum|Forum|7 years ago
September 12, 2018
4 replies
3615 views

Hi folks,

i can something that i don't understand in ae since 2005. maybe someone can give me an answer to the following question.
why does an object which is travelling from a to b and with a pause from b to c switch its orientation during a rest? the moment the movementspeed reaches 0 pixel / sec the orientation of the object jumps to a "resting position" and as soon as the speed is >0 px / sec it jumps back to the normal orientation. this "feature" doesn't make sense for years. maybe someone smarter then me can explain to me why .

This topic has been closed for replies.

R

Rick Gerard

Community Expert

It actually makes sense to me that if the motion stops the orientation reverts to the at rest instead of staying put. I almost never do the kind of animation in your example using auto-orient along path. I'll put a null on a motion path and set up a lookAt expression for rotation so I can more easily control the anticipation to a turn. If I do run into the problem I'll just move the second keyframe one pixel toward the next move.

B

blickfeldAuthor

Participating Frequently

i don't talk about this animation. this was just an example to show what i mean. and if the motion stops, it doesn't revert else it must revert when the motionpath stops . and when the motion path stops it doesn't revert. and i'm searching not for a technique to control it. there are plenty of techniques i use for animation. it was just curiosity if someone got a real life chase, when this behavior makes sense.
i just promised my stundents that i would research if there is any other reason except math why this happens.
but thanks all together. i guess there is no answer to this.

P.M.B

Legend

There seems to be a communication breakdown going on here.

You're being offered fixes and better workflows when it seems to me your (or your students) real question is "why hasn't it been fixed"?

You say your students are asking "is there a reason other than math?":

Answer is "NO".

Everything that a computer does is because of & limited by the known laws of mathematics. Period. Full Stop.

So, why hasn't it been fixed?

With all due respect it's a pointless question. Any possible answer would be pure speculation & assumption.

If I were their teacher I would take the opportunity to teach a lesson in logic and critical thinking.

To teach them the difference between a question that can be objectively answered and one that cannot.

~Gutterfish

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blickfeldAuthor

Participating Frequently

i get the mathematical reason behind this and im using an expression to avoid it. but, exect in math, this behavior makes so sense. or i can't see a single reason why this behavior is useful.
sorry for my english, i'm no native speaker.
i just ask myself why adobe haven't fixed this behavior for more then 10 years. but maybe someone can give me an exsample when this behavior would make sense. like i said not mathematical sense but in practical use.

p.s. how to mark this thread as not answered?

P.M.B

Legend

blickfeld wrote
p.s. how to mark this thread as not answered?

By not marking it answered. All questions are considered unanswered until someone marks them as answered

~Gutterfish

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Rick Gerard

Community Expert

Auto-orient is useful in a bunch of situations and it's pretty easy to overcome the problem that pops up when you stop the motion. You don't even need to use an expression, all you need to do is grab the pen tool, hold down the Alt/Option key and delete the handle on the path if it exists where the layer changes direction, copy that keyframe, move down the timeline to where you want movement to start again and paste then use the arrow key to move the layer 1 pixel in the direction of the motion. Nobody will see the 1-pixel movement over several frames but the layer will not flip back to the resting position. You can also use the graph editor to modify the speed between keyframes to keep the layer pointed in the right direction.

Animations like this that don't accelerate, decelerate or make a few frame transition to a different orientation don't look very good anyway.

Mylenium

Legend

Sure, it makes perfekt sense - a zero-length vector can't be used to determine a persistent orientation and that's exactly what you get when your object is static. If you need it to work differently, you have to create your own logic with expressions and assign a custom initial vector.

Mylenium

Mike_Abbott

Legend

My guess - and it is a guess, is that the algorithm for Auto-orient is comparing the objects current and 'previous' position (let's say the previous frame) to calculate the required orientation. If there is no difference in those values, ie the object is stationary, that calculation isn't possible - hence the lack of orientation.

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