[Gridflow-dev] #centroid: added two extra outlets

Mathieu Bouchard matju at artengine.ca
Thu Jun 16 21:02:27 EDT 2005

On Thu, 16 Jun 2005, Alexandre Castonguay wrote:

>> [#centroid2] whenever possible. If you want to add the same feature to
>> [#centroid2] it's only two more lines of code but it's C++.
> Good, can you add it ;-?


> So [#centroid2] could be used with voxels to get frame number values and 
> centroid position at once? What would be returned by the 'x' and 'y' 
> position outlets in that case, would it break?

I don't know what would be returned by them... if x and y are considered 
to be the "2nd folded dimension" and "1st folded dimension respectively, 
then "frame" (or "z") would replace "y" and "y" would replace "x" and 
maybe a new outlet for "x" would be added. However if x and y are 
considered to be the "last folded dimension" and "next-to-last folded 
dimension", then it would be compatible with your proposed behaviour, but 
the "frame" (or "z") value would not be available as a separate outlet or 
it would be available in a non-standard order.

the value of "x" and "y" would be the same as if you layered all 
constituent images with equal weight, as with [#fold +, seed (240 320 1 
#)] -> [# / 50] (if there are 50 frames in greyscale 320x240), and the 
value of "frame" would be the same as if you did [#import (240 320 1)] -> 
[#downscale_by (240 320) smoothly] -> [#redim (50 1 1)] -> [#centroid] and 
then picked the y of it.

> Maybe there should be only one [#centroid] object? I would opt for the 
> fastest.

Yeah, #centroid2 was supposed to be a temporary name only for testing, but 
after the project at the Museum of Civilisation of Quebec City, I forgot 
to rename it.

OTOH, it would be a good thing to keep the abstraction one, because it can 
be a good test patch for accelerating GridFlow. It would be cool if the 
gap between both #centroid's became narrower due to improvements to both 
the patch and the underlying objects (e.g. faster #fold or anything). It 
would have a positive impact on several other patches and abstractions.

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