I have a question:

When I am rotating an object in relation to a second fixed object, the rotated object rotates to the desired angle OK.  However, DURING the rotation the rotating object displaces from the original axis point.  In other words the 'anchor point' of the rotation displaces as the rotation occurs.  The 'anchor point' returns to the original position by the end of the rotation.

I'm rotating the object 45 deg.  I'm using AL 5 with TC Pro 18 32 bit.  How can I prevent this drift / temporary displacement?

I welcome your input!   

Assuming no other commands are involved, the rotation should be around the objects own 'extents' coordinate system based on the reference point, so what you describe shouldn't happen unless the reference point is slightly off, can I ask -  are you using commands or keyframes, any chance you could post a sample file as its easier to see what is happening.

Andy

Andy,

Thank you for the reply!  I'm using Key Frames.  I have one stationary horizontal object (group) and one vertical object (group) that rotates.  I'm using the 'Transform' rotation tool.  The anchor point for the rotation is the center of the hole in the vertical object.  I have attached the .tcw drawing and .avi animation.  I hope the animation file is not too large to attaché.

As you can see in the animation, the vertical object displaces downward during the rotation.

Hope this gives you a better idea of my problem.

Ted

Keep getting INTERNAL SERVER ERROR  will try with .tcw only, then maybe separate post with .avi

The .tcw file attached OK!

Some difficulty with attaching .avi file.  Will try again early in the AM.

HI, TC file was fine,

What is happening is that the ref point moves by the shortest distance between two keyframes, if you hover over a keyframe and right click, select keyframe properties, you will notice both position and rotate is clicked, and because position was ticked (by default) when the keyframes  were recorded, the object is essentially moving as well as rotating.

Unfortunately once keyframes are recorded, simply moving the ref point doesn't work,  in the attached TCW file I left position ticked but altered the ref point to the centre of the circle, (which I've marked with a cross), them re-recorded the keyframes, as the ref point doesn't actually move it wasn't necessary to turn off position before recording the frame.

Hope that makes sense.

## Edit ## to show the ref point movement, in the attached Gif (click the Gif to show animation), the blue star is the original reference point and the red line the distance between two keyframes   ## End edit ##

Andy,

Thank you for the helpful feedback.  I see the 'movement' of the reference point from the original position to the new position as causing the anchor point displacement.

My understanding of the 'reference point' is that it is the point selected after the 'anchor point', is that correct?

Thank you again!

Ted

Andy,

I have an update. 

Firstly, I need to confirm the term 'reference point'.  I'm assuming that this point is the same as 'anchor point' established by using the Transform  - Rotation tool.  In other words this establishes the axis point of the rotation.  Is my understanding correct??

Secondly, I was unable to open your .tcw file, I'm supposing you generated that file with something newer than TC Pro 18.2 and my 18.2 will not open it!

Thirdly (and perhaps the most important) when I set up the animation to revolve the part as usual using the Transform - Rotate tool and set the Key Frame properties to Rotate (with 'Position' not checked), the rotation is centered on the group mid-point and not the anchor point previously established!  'Rotation' and 'Position' both being checked give the best result, but still not staying on axis for the reasons you described.

I've tried various approaches, and none really work to my satisfaction.  The displacement during rotation is a 'show stopper'.  Plus, the example given is only one simple segment of the complete job.  Other linkages need to move and rotate simultaneously (and stay on axis)!! 

I'm starting to think that AL 5 is only somewhat compatible with TC Pro 18.2.  What are your thoughts?

Again, thank you for your interest and help, much appreciated!!

MY apologies, I didn't pay enough attention to the version, the attached file is now v18, unfortunately I only have 64 bit version of AL installed so I can't run an animation in v18, but it should hopefully work (saved back to v18 after testing in v19).

1).  The reference point that AL uses is the standard ref point (x,y,z) of any object, irrespective of any operation like transform which is carried out, this is normally the centre of extents when an object is created, in the file I used the seke (keyboard shortcut) 'D' to pick up and put the reference point into the centre of the circle before re-recording the key frames.

2).  Sorry - see new file attached to this post.

3).  Yes, AnimationLab takes no notice of any transformation points, and uses the objects own reference point whether single or group ref point.

Once you get used to moving the reference point to the point of rotation before recording keyframe you shouldn't have any problem rotating anything, there is one quirk, in that if the reference point is moved after a keyframe is recorded, then whilst the recording will use the new ref point of the object/group, it will move this point and the object to the coordinates of the pre-recorded point, this is because the keyframe editor records the x,y,z of the reference point at that moment in time, so if the reference point is subsequently moved, AL will shift the position of the object/group so that the new ref point will be at the exact x,y,z coordinates it has recorded.

One needs to re-record the keyframes if the reference point is moved, this only applies to keyframe editor, commands work differently, sorry if I make it sound complicated, its not really.

Andy -

Thanks - the TC 18 version works great. 

I was successful in moving the reference point as you instructed verses using the Transform tool.  I'm very happy with the outcome and ever so grateful for your help.

My next step will add the link (not shown) that attaches to the vertical object on one end and a sliding member (not shown) on the other.  The sliding member will move horizontally along the stationary object axis as the vertical object is rotated.

So the link will rotate and move, while the sliding member only will only move.  I'll work on that later!

Again, thank you for your help and have a good day!!

Ted
SE Queensland Australia