Rotation about X or Y-axis


#1

I hope I have the correct page for this question; if I don’t, please bear with me and I’ll try to hit the mark next time around.

I’m attempting to rotate a bitmap [or a vector, for that matter. I stalled on that problem several months ago] around its centre line vertically, as per the image below: basically, think of a coin spinning on its edge - you see the image ‘backwards’ when the coin faces ‘away’.

Rotating around the Z axis is easily allowed for in Synfig, but I’m having a head-scratcher of a time working out either of the other two dimensions.
Could anybody point me in the right direction, please?

QuinB


#2

Hi
how did you do that? You used group transformation?


#3

I’m trying to find out HOW to do this in Synfig.

This is a LightWorks 3D effect applied to a GIMP-created 2D image and I’d like to be able to get Synfig to do the same. Easily.

My nearest effort under Synfig (which I’m relatively new at) was to reduce the X dimension, narrowing the work to a line, and then duplicate and mirror the image and effect, taking it from a line to full width again - a method which seemed imprecise and time consuming. I was hoping one of the Synfig sky gods could advise on a better method.

Q


#4

i used group transformations for this one…
it’s a bit difficult to put the axis point precisely, though (there are some leftover guides in there…)

spin.sifz (9.06 KB)


#5

Thanks - I’ll check it out.
I was surprised there wasn’t a specific function for it. (Proves how good I think Synfig is).
Q


#6

Fadhilkwan,
Thanks - getting the idea - I need to tinker a bit more to get things right, but I think I’m getting there.

Q


#7

Hi,

I think the most “Synfig way” to achieve your goal is to use the Converters.
First you need to create a group containing all your elements.
Fadhilkwan, I stole your sample without any shame :mrgreen: and I went deeper.

We will play with the horizontal scale as well but directly with a periodic (alternating) movement.

Select the “Coin” group layer.

Expand “Transformation” and select “Scale”
We will split its X and Y axis
Right-Click / Convert / Composite

Expand “Scale” and select “X-Axis”
We will transform it as a periodic movement (Cosine)
Right-Click / Convert / Cos

Expand “X-Axis” and select “Angle”
Its spinning speed is constant, so it will be a linear
Right-Click / Convert / Linear

Expand “Angle” and select “Rate”
Rate is the degrees of rotation per second
I set it as 180 so a full spin takes 2 seconds

Let’s try it, it works all by itself :slight_smile:
Converters are one of the most powerful functionnalities of Synfig.
At first it looks tricky but it is only a matter of logic :wink:

You will find more information about converters in this tutorial:


Link

So it is the proof that Synfig is as good as you thought ^^
SpinCoinConvertersBase.sifz (3.55 KB)
SpinCoinConverters.sifz (3.64 KB)


#8

That reads interestingly.
I’ve just pulled the files in and I’ll check them out - thanks a lot for taking the time to educate

Q


#9

I was blown away by that tutorial the first time I saw it - I couldn’t manage to make anything I tried based on it work, but it was inspirational and appealed to my ideas of how animation Should Be.

Here’s the technique applied to the same bitmap as above:

I exported to png before creating the gif and manually removed the empty frames where the bitmap is ‘edge on’; laborious, but provides a smoother effect.

I’m not having any luck reversing the direction of spin - yet. Tomorrow’s a new day, after all.
Thanks for the input!
Q


#10

sure, you’re welcome!! :mrgreen:
nice tricks by the way, i kinda get the mechanism for it :bulb:


#11

By the way, we can add some horizontal and vertical jig to the coin to look more natural.
As well as before, we use converters on a “Jig” layer, whose Offset will be split in composite.
This jig will be connected to the Cosine of the rotation (which will be an exported value, varies from -1 to 1).
Then it is multiplied by a scalar factor (which depend also on the Scale property, I set 0.4 for X-Axis and 0.05 for Y-Axis).
:wink:
SpinCoinConvertersJig.sifz (4.06 KB)