[x3d-public] OrthoViewpoint fieldOfView - and display size

[Andreas Plesch]

On Mon, May 7, 2018 at 2:49 PM, Andreas Plesch <andreasplesch at gmail.com> wrote:
> On Mon, May 7, 2018 at 1:28 AM, Don Brutzman <brutzman at nps.edu> wrote:
>> Thanks for multiple helpful postings on this topic.  Offhand I'm not
>> remembering special rationale involved.  Good question for CAD experts where
>> OrthoViewpoint view is more commonly used.
>
> ..
> Another aspect which I am not quite clear about is navigation from a
> Orthoviewpoint, along the viewing direction. Strictly speaking,
> orthographic projection would mean no zooming during such navigation.
> The zoom is only defined by the fieldOfView. However, the user
> expectation would be zooming during such navigation which then leads
> to some interaction between location and field of view. I should test
> how browsers behave but any insight would be much appreciated.

Using as a test for navigation along the viewing direction:

https://github.com/castle-engine/demo-models/blob/master/navigation/ortho_viewpoint.x3dv
https://raw.githubusercontent.com/andreasplesch/Library/master/Tests/Components/Navigation/ortho_viewpoint.x3d

no zooming when navigating along viewing direction:

- x_ite
- view3dscene
- InstantPlayer
- freeWRL
- octaga
- h3dviewer

zooming:

- x3dom

na:

- BSContact

The majority of browsers applies the orthographic projection such that
only the fieldOfView controls the 'zoom' level and the distance of the
viewpoint to any object is irrelevant. This is strict and a bit
counter-intuitive but probably does not need any clarification in the
prose.

-Andreas