[Bf-committers] Camera Guides

[Campbell Barton]

On Thu, 2011-05-05 at 20:03 +1000, Michael Fox wrote:
> In the past few days i have been working on adding guides to the camera 
> object, to be used for perspective and eye line tracking  as well as 
> composition guides (rule of thirds, etc etc) ,  now granted there is 
> patches available to do this but they are all hardcoded and don't allow 
> for much in the way of adjustment or precision, and certainly not 
> elegant or integrated well.
> 
> However there has been concerns over this feature is really necessary, 
> like people should use BG images or Grease pencil, really slapdash stuff 
> and that custom guides are not needed nor should be developed, so I 
> would like to ask, do I continue on this project, or call it a day and 
> let the patch pass around the community because I do not want to keep 
> going if it is deemed of little or no interest or need.
> 
> the Patch
> http://mfoxdogg.com/development/cam_guides.txt
> 
> Pros.
>      -uses SDNA/RNA
>      -fully accessible via python
>      -update real-time
>      -both ends of each guide are independent and can be put anywhere in 
> the area of the camera
>      -has a transparency value
>      -position values are percentages of the camera area so no need to 
> redraw guides if resolution or camera scale change
>      - due to accessibility of python, a preset system could be 
> developed for this
>      - guides are saved in the file
> Cons
>      -only exist in camera view
>      -only a dashed line and no colour support at this time
> 
> The patch has a few issues
>      - need a way to clear memory made where the guide is made
>      -due to this files saved with guides will crash
>      -the remove guide button does not work, for some reason
>      -only very basic UI has been developed
>      -no documentation at this time
> 
> Now please don't view this as me sulking and being a primadonna its just 
> i have very little time these days and havn't developed anything for a 
> while, there is not design docs for the object colour rules system yet 
> so i took on this challenge, which has been in the back of my mind for a 
> long time.
> 
> Thank you for your time
>      Michael B. Fox
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It seems to me that this is spending energy on a feature which is mainly
useful in corner cases, while grease pencil isn't perfect, I think with
some minor tweaks it can work very well.

Suggest to do this instead:
* Add generic overlay presets like golden rule, center, diagonal lines?
There could be 3-6 of these that can work like existing tile safe.

* Rather then adding new code, use grease pencil for this feature, the
only change needed is show a cameras grease pencil while in the camera
view - irrespective of selection.

* Modify the SVG importer to optionally load paths into grease pencil or
import SVG and convert curves to grease pencil internally.

--- (end implementation details)

For users this can be made as simple as a button in camera panel:
"Load SVG to Camera Grease Pencil".

This avoids adding DNA, rna api, editing tools etc.
If people really like to make some detailed camera overlay that cant be
drawn by hand in grease pencil they can use inkscape and import it.