[GRASS5] Re: nviz testing

Paul Kelly paul-grass at stjohnspoint.co.uk
Fri Feb 28 05:53:39 EST 2003

On Fri, 28 Feb 2003, Paul Kelly wrote:

> B) In the geoview struct a comment says the direction of rotation is
> right-handed, i.e. clockwise facing away from the origin. But both d.3d
> and SG3d interpret the value as a twist in the (unconventional)
> anti-clockwise direction. As this seems to be the GRASS convention
> therefore I think nviz should be changed to take account of this- simply
> putting a minus sign in front of the value saved / loaded from the 3dview
> file. [nviz load and save 3dview were both consistent in this regard, but
> files saved by nviz weren't consistent when viewed in SG3d or d.3d].

Sorry, looks like I was slightly mistaken on this. Actually d.3d ignores
the twist value and uses the default of 0. And a comment in the definition
of the 3dview struct also says the direction of rotation should be
clockwise. So it looks like the bug is in SG3d, or maybe a 'feature' as it
has been there so long. In the SG3d GUI the 'twist' dial definitely
appears to be upside down, so presumably there is a reason for it.

So I will wait for futher insights into this, but will go ahead and fix the
scaling and rounding bugs now.


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