Action resolution in expression?

Hi All.
Again, New expression question.

How do we have access to action resolution in an expression? for example, I would like a new layer to be placed at 3/4 of the frame and do that with an expression, without having to change values by hand.


And by the way, is there a a complete and exhaustive document that would reference all functions, attributes etc available in flame expressions? with for each the way to use it?

I can’t find that. There are a few exemples in Flame documentation but it looks quite poor regarding to expressions.

I courd swear I saw such a documents years back but I can’t find it now… :frowning:

We don’t have access to canvas resolution as far as I know. But I think we can calculate a value depending on the camera fov and position. I’ll have to take a look at it, maybe @ytf has it handy.

As far as the document I still keep a copy of Flame 2013 manual as a pdf. I even have the expression part exported as a separate document.

flame_expressions.pdf (895.6 KB)


You can derive the resolution with a formula that uses the default camera’s distance, near and FOV values. I would have to spend a little time to figure out exactly how to tailor that to your needs.

1 Like

Thx for the pdf. It’s actually the same as in Flame 2023 documentation, but still very handy to have that part in a small pdf. Thx.

Ok, I’ll have a look and try to figure it out by myself. Chances of success…5/100. But still. :slight_smile:

The Y is easy: (2*(tan(radians(.5*Default.fov))*Default.position.z))

I use a similar function to determine scale, but it occurs to me I may not be calculateing for X when I do it and there is a strange relationship between the near value and the position.z value that I can’t remember offhand.
I will think of this in my copiuos free moments today

1 Like

Thx. But I need to revise my chances of success alone. New estimation : 0.0000001/100

When someone says it’s easy …

It’s just two times the tan radians


So there is a pretty straightforward, simple way. My issue with it is that you need to add the background as a surface, which has been possible for about 3 or 4 versions.

Drag the background into the action schematic and name it background.
The H resolution is 2(times)background.lensDistort.centreX.
The V resolution is 2(times)background.lensDistort.centreY

Because the forum identifies the asterix as some sort of html function, everywhere I wrote (times), use an asterix.

I believe this is case sensitive.


basic camera math: fov= 2*(atan(.5Aperture/focal length))