[vtkusers] How to preserve objects size when moving camera

[Andrey Ivanov]

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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