[Kstars-devel] Stars drawing (speed and color)

[Akarsh Simha]

On Mon, Nov 02, 2009 at 08:39:13PM +0300, Alexey Khudyakov wrote:
> > Follow-up on this subject
> > 
> Another problematic place is StarObject::initImages. It uses pixmaps of size 
> 15*SkyMap::Instance()->scale(). Then algorithm which actaully create pixmaps 
> assume that they are 15x15 pixels. Which behaviour is correct?

I think they can be 15x15, since the star size is recomputed using the
zoom factor anyway. If that's the screen scale, it still shouldn't
matter. What we must preserve is the relative sizes of stars. I think
it's okay to use 15x15, unless it looks awful on some very big
displays. Which one will be faster?

> And last one is
> > double StarObject::pmMagnitude()
> > {
> >    return sqrt( pmRA() * pmRA() + pmDec() * pmDec() );
> > }
> If this functionfion calculate absolute value of proper motion it should use 
> following formula:
> 
> sqrt( v_{RA}^2 * cos(dec)^2 + v_dec^2 )

Hmm... you seem to be right, and that also means that I'll need to
regenerate USNO NOMAD! I'll work on this next weekend, hopefully. But
feel free to experiment around.

Regards
Akarsh