Combustion - Link a mask vertex to a Null Object

#1

Hi! I´d like to know if it is possible to link a mask vertex to a null. I am working on a project and that would help me a lot!!

#2

Yes it is. You just need to write a expression to compensate the differences between the scene origin at op level where X,Y zero is on the left top corner of the frame and at comp level where 0 is on the middle of the frame.

I have a workspace published on Alex Udell FTP showing how to do that, it’s called pinning line to text.

But basically this is teh expression you may write.

On the X of the point you want to link write:

Xvar = CB.GetChannelValue( “<path to the null object>/Transformation/X Position”, CB.GetCurrentFrame())

Xoffset = 320
Xvar + Xoffset;

On the Y of the point you want to link write:

Yvar = CB.GetChannelValue( “<path to the null object>/Transformation/Y Position”, CB.GetCurrentFrame())

Yoffset = -240
Var1 = Yvar + Yoffset
Var1 * -1;

I hope it helps.

Cheers,
Diogo

#3

Hi Diogo!!

I tried your expression here and it worked 50%… :smiley:

The X value was ALMOST right… The X value seems to slide a little bit from the exact location and the Y value doesn’t seem to work at all because it gets stuck on the top of the composition…

What’s am I doing wrong?!

Fala cara! Tu é da Twister!! Como anda o filme da xuxinha? Vai dar tempo!? Eu te adicionei aqui no meu msn, ve se aparece de vez em quando pra gente trocar uma ideia!!

#4

I would have to see your project to se what’s wrong. But make sure both your paint op and your composite have the same resolution, also make sure you’ve edited the Xoffset and Yoffset variables values of the expression to values that correspont to the resolution you are using in your comp.

Talk to you soon.

Cheers,
dg

#5

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