[vtkusers] How to preserve objects size when moving camera

[David E DeMarle]

Will turning off perspective do what you want?
https://www.vtk.org/doc/nightly/html/classvtkCamera.html#a5b0e647798e7f45d358d8039ff41b378
void vtkCamera::SetParallelProjection(vtkTypeBool
<https://www.vtk.org/doc/nightly/html/vtkABI_8h.html#a663dee2c85b2a185fb34cb877d5208da>
 flag)

David E DeMarle
Kitware, Inc.
Principal Engineer
21 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-881-4909


On Fri, Dec 14, 2018 at 10:55 AM Andrey Ivanov <andrei.ivanov at phystech.edu>
wrote:

> Hello!
>
> I am trying to draw a lot of objects with the same shape for CAD system.
> Let it be stars or circles for example.
> The number of such circles can be about 1000-10000.
> I would like to *preserve their size* when moving the camera, scaling
> frustrum and changing distance to objects.
>
> For now I found two approaches:
>
> 1. Use vtkDistanceToCamera
> An example from
> https://lorensen.github.io/VTKExamples/site/Cxx/Visualization/DistanceToCamera/
> is great
> for low number of objects, however when their numer grows, the interface
> starts to freeze due to
> rescaling of shapes on each interaction with camera.
>
> 2. Use points (squares with width equal to 4 pixels).
> It works fast and points size is fixed, but I would like to have more
> complex shapes, like triangles and circles.
>
>
> Is there another approach to solve this problem? It seems that with pure
> OpenGL this can be implemented rather efficiently,
> so I am looking for a way to do it in VTK.
>
> Best regards,
> Andrey Ivanov
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