[vtk-developers] vtkTextActor rotation

[David Cole]

I would say the text should look good and be legible when it's rendered...

Would anybody here really prefer perfect backwards compatibility
(including text illegibility) over better visualization...?

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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