Re: What would you do with paths?
Re: What would you do with paths?
- Subject: Re: What would you do with paths?
- From: Peter Litwinowicz <email@hidden>
- Date: Fri, 26 Jun 2009 15:53:22 -0700
- Thread-topic: What would you do with paths?
> FxPlug Developers,
>
> We're looking at how other APIs allow plugins access to path data.
> We're curious what your plugins do with path data.
>
> In particular, I'm looking at the After Effects API, and see a variety
> of functions for dealing with segments and vertices. I'm wondering if
> any of you either have existing plugins that use these, or if you
> think you would use similar functionality if it existed in our
> applications.
>
> For example, the PF_PathDataSuite allows you to get the length of a
> segment between 2 vertices, as well as to get the x and y position of
> a pixel that is some length along the segment. It also allows you to
> evaluate the first derivative of a point on a segment.
>
> So my questions to you are:
>
> 1) Are these functions useful? Do they do something you need to do?
When you say "these functions" I presume you mean the ones you listed and
not the entire AE specification?
We need to be able to get each vertex, we need to be able to evaluate points
along the curve: and that includes by equal spacing in the output space, and
by equal spacing in the parameter space (which are not the same thing!). We
do lots of matching up of evaluate points along a spline segment to a
corresponding place on another spline segment.. And doing that in the
parameter space is pretty much useless.. You want to match up things based
on their distance in the output (screen space!).
> 2) Do you prefer to work with vertices, segments, or the entire curve?
Yes. All the above.
> For example, would it be better to be able to retrieve the x,y
> location of a point that is a certain distance from the first vertex,
> rather than a certain distance from a particular vertex (or along just
> a particular segment between 2 vertices)?
We often match up corresponding places on two splines by matching up the
vertices and the places along the segment inbetween the vertices. And we'd
want to do that based on distance in the output space, in a measure of
distance from a vertex, not just along the entire curve.
Also of use: if we are having pairs of splines representing "src" and "dest"
places for a warp or morph, it would be useful to hide half of them (only
source the Src shapes, or only show the Dest shapes).
It would also be useful to delete vertices internally and add vertices
programmatically. So that if one spline of a pair has a vertex added by the
user that we can add a vertex in the corresponding place on the other spline
automatically (by us internally).
> 3) Is anything missing? Are there other pieces of data about paths
> that you'd like to have that you don't currently?
See above.
It's also imperative to be able to attach our own settings on a per-spline
basis. For example, being able to attach a floating point param (or many
:-)) to each spline, and a menu item, and a color, or whatever.
Also, if the plugin can access the spline, then it should be attached to the
plugin itself, and not to a clip or sequence. After Effect's model of where
the spline exists is WRONG ;-). For a much better approach, you should view
how combustion attaches the spline to each plugin (so there is no ambiguity
of how the spline is being used!)
>
> 4) Do you have any currently shipping plugins that use path data? If
> so, which ones?
Yes: see our SmoothKit set (we have a directional blurring filter that uses
splines to control the direction of the blurring) and our RE:Flex set
(morphing and warping).
>
> As usual, we're just thinking about different things. We aren't in any
> way promising that we'll implement something like this. But we want to
> know a) how useful it would be, and b) if we did implement it, what
> would you want it to look like?
Darrin, what you propose is a great idea, and we definitely have some good
ideas of what to do, and what NOT to do. Perhaps this warrants a phone
conversation?
Pete
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