[vtk-developers] vtkTextActor rotation

[David Lonie]

Update: Still looking for reviewers! =) There are a handful of patches, but
most of them are quite small...

On Wed, Oct 15, 2014 at 10:19 AM, David Lonie <david.lonie at kitware.com>
wrote:

> Hi all,
>
> I finished up a patch to better handle rotated and aligned text, and
> cleaned up a few other rough spots in the text rendering system.
>
> Looking for reviewers:
>
> http://review.source.kitware.com/#/t/4851/
>
> Dave
>
> On Wed, Oct 8, 2014 at 3:52 PM, David Lonie <david.lonie at kitware.com>
> wrote:
>
>> Hi Folks,
>>
>> We've noticed some odd behavior while rotating 2D vtkTextActors. There
>> are two ways to do it:
>>
>> vtkTextActor::SetOrientation(degrees), or
>> vtkTextProperty::SetOrientation(degrees)
>>
>> These behave very differently, especially when alignment flags are used
>> -- see the attached image for an example. The bottom two rows show this
>> most clearly.
>>
>> Rotating the text property will rotate the text as it is being rendered
>> into the texture's buffer. This gives great antialiasing on the rotated
>> text, but gives bad alignment results, since the vtkTextActor is currently
>> aligning the entire texture to its position, rather than the text inside
>> the texture.
>>
>> Rotating the actor gives the expected alignment behavior, but bad
>> antialiasing. This is because the text is rendered into the texture without
>> rotation, and then rotated afterwards.
>>
>> Combining the two (top row) gives the worst of both cases.
>>
>> I'd like to fix the text actor to align things "correctly" when the text
>> property is rotated. So my questions:
>>
>> 1) Is this behavior expected due to backwards compatibility?
>> 2) If not, is this a good time to fix this? (e.g. are there any upcoming
>> releases I should hold off for?)
>>
>> Thanks,
>> Dave
>>
>
>
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