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mogh
06-19-2012, 07:55 PM
How to Animate Rotation per second with expresso with speed changes?

I use the Xpresso Coffe Node Preset from the Xpresso Node Library (not from the content browser but from that xpresso side bar) to animate a rotation per second.

I increase the speed by linking the 1/sec input to a slider and animate that. Now as a result I get Aliasing/umping behavior of the rotating object.

I also tried the base 80 node with no luck in animating the roation per minute in this case.
http://www.base80.com/index.php/2005/08/14/rpm_bpm_nodes

How do I solve this or make a proper Xpresso setup.
I would like to have a rotating object where I can increase and decrese the speed in an animation without trouble.

Thanks for your help in advance.

kind regards mogh
tcastudios
06-19-2012, 08:37 PM
You add the RPM value to the current rotation value.
(Drag the object twice into xpresso manager and a Math Add Node inbetween,
make sure they are in the correct falling order in the xmanager (left pane in xpresso manager))

Add an if switch the check if current frame is not the same as last frame not to
get rotation when scene is stopped.

Cheers
Lennart
mogh
06-20-2012, 09:53 AM
Thanks Lennart

http://forums.cgsociety.org/attachment.php?attachmentid=168072&stc=1

It seems to work but I've to stresstest my setup ... to be suer I understood what you said.

I marked the important falling order in the xmanager on the left.

kind regards
mogh
tcastudios
06-20-2012, 03:04 PM
What I meant was to make a set up from scratch.
As I understand it that RPM node is time dependent.
You need to make a set up that only looks for last frame.

Look at attached picture, it includes to compare nodes, one
for checking if the scene is running (current time != last time)
and the other checks if you are at first frame (frame 0) and
sets an initial value (or you can't get a repeatable animation.

Keep in mind that frame dependent set ups must be played from start
to get the same animation as opposed to time dependent set ups.

Cheers
Lennart

http://tcastudios.com/tempfiles/xpressorotor.jpg
mogh
06-20-2012, 09:12 PM
Thanks your setup seems to work for me,

one question do I have to start from the beginning of the animation to ausre proper rotation in case i want to rerender some frames in the middle ?

kind regards
mogh
tcastudios
06-20-2012, 10:04 PM
Glad it worked out for you!

It would be a good idea to bake the animation just to be sure.

Cheers
Lennart