Question?? about how to orient

astroanalyst

astroanalyst

Well-known member
I have an item in the middle of the screen and I want other items to rotate around the center item BUT keep their vertical positioning (see image).

I know I could make keyframes at every corner but I was looking for a simple method of keeping the orientation of the circling items while rotating around the center item.

1161523598.jpg
 
Use the pan behind tool (y shortcut key) to move the anchor point of the small question marks to the center of the large question marks. The anchor point will show up as a circle with an X in the middle, when the layer is selected.

If its an NTSC comp, and you center your middle ?mark, then select all your layers and press A, then type 320, 240 in one of the layers anchor point, and if they are all selected, then they should all change.

You can also parent them to a centered null, so that they animation part is easier, or you can use expressions. If you're going to animate them to rotate around, I would parent them to a null. If you want the small question marks to stay upright, then you have to hand animate their rotation at the right points, or use some kind of expression.
 
My main goal was to get the small question marks to stay upright as they rotated around the center. I guess I'll have to do it manually.

thank you!
 
astroanalyst said:
My main goal was to get the small question marks to stay upright as they rotated around the center. I guess I'll have to do it manually.

thank you!
Click to expand...

Use an expression...much faster and probably better results.
 
Ok I figured it out...
I made one small question mark. Then moved the anchor point to the middle of the big question mark. Then I made a mask and made the small question mark track the path. This kept it upright the whole time...

Then I duplicated the small question mark a number of times and offset the start times to fill the whole circle.... around they go!
 
Being that you are using rotation already, using an orient expression won't really work, as your anchor point is adjusted so it rotates around the big question mark. So, I'd do it like this:

For position of the small question marks, use:

amp = 300;
speedFactor = .5;
t = (1/thisComp.frameDuration)*(time*(speedFactor/10));
x = value[0] + Math.cos(t)*amp;
y = value[1] + Math.sin(t)*amp;
[ x , y ]

This will put the question mark in a perfect circlular motion. Then, if we call the main question mark layer "Big Question Mark", we can use for the rotation of each of the other question marks:

r = thisComp.layer("Big Question Mark").toWorldVec([1,0]);
radiansToDegrees(Math.atan2(r[1],r[0]))
This will orient them in the same angle as the layer "Big Question Mark"

Make sure to change "Big Question Mark" to the appropriate name.
 
I got it to work but I think I failed to mention one step. Here are the steps again

1. Create one small question mark
2. Move anchor point to middle of large question mark
3. Create a path using the mask tool
4. Cut and paste mask path into position path of small question mark
5. Use loopOut(type="cycle") as expression for position of small question mark
6. Duplicate small question mark a number of times and offset times
7. Precomp and use it a number of times in the final movie


This is the results
http://riderpublishing.com/question_1.mov


Graymachine... I wish I could do math like you do!... your site is great!

Thank you
-astro
 
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