[Freeciv-Dev] Re: [Patch] Fortress with enhanced vision (watchtower-like)

[Raimar Falke <hawk@xxxxxxxxxxxxxxxxxxxxxxx>]

On Sat, Aug 25, 2001 at 07:39:48PM -0400, Jason Dorje Short wrote:
> > > Another issue to have a more fine grained control over vision
> > > range. The vision range is currently a square with the dimensions
> > > (vision*2+1)X(vision*2+1). Maybe this could be changed to somelike
> > > like:
> > >
> > > vision=1:
> > >
> > >    x
> > >   xux
> > >    x
> > >
> > > vision=2:
> > >
> > >   xxx
> > >   xux
> > >   xxx
> > >
> > > vision=3:
> > >    x
> > >   xxx
> > >  xxuxx
> > >   xxx
> > >    x
> > > vision=4:
> > >   xxx
> > >  xxxxx
> > >  xxuxx
> > >  xxxxx
> > >   xxx
> > > and so on.
> > 
> > Yes, I see, this could possibly be used for other stuff as well, but is
> > this implemented in some way already or would this have to be done
> > completely new? Probably I could do this, but for that I'd have to take
> > a closer look at the tile-coordinates-handling...
> 
> I had some thoughts on this before.  There are three ways to measure
> distance:
> 
> (1) Use the lateral distance.  Thus distance=max(x-x0,y-y0).  This is
> what you're doing now:
> 
> 3 3 3 3 3 3 3
> 3 2 2 2 2 2 3
> 3 2 1 1 1 2 3
> 3 2 1 0 1 2 3
> 3 2 1 1 1 2 3
> 3 2 2 2 2 2 3
> 3 3 3 3 3 3 3
> 
> (2) Use the "manhattan" distance.  The manhattan distance is the sum of
> the distances along each axis (or, in Manhattan/New York City, the
> number of blocks you must walk to get from point A to point B). 
> Manhattan distances are like so:
> 
>       3
>     3 2 3
>   3 2 1 2 3
> 3 2 1 0 1 2 3
>   3 2 1 2 3
>     3 2 3
>       3
> 
> (3) Use the direct "pythagorean" distance.  This is the distance of a
> straight line between the two points, calculated using the pythagorean
> formula, so that your resulting shape corresponds to a circle.  The
> following table shows the *squares* of the distances:
> 
>       9
>   8 5 4 5 8
>   5 2 1 2 5
> 9 4 1 0 1 4 9
>   5 2 1 2 5
>   8 5 4 5 8
>       9
> 
> Which one of these is the closest to the way FreeCiv works now?  Well,
> most people would tell you #1.  In fact, the answer is #3.  In all cases
> that I know of, FreeCiv's areas correspond to circles.  But, the
> pythagorean distance is never used internally - it's always some special
> case like vision=1 (a circle of radius sqrt(2)), vision=2 (a circle of
> radius sqrt(8)), or citysize=2 (a circle of radius sqrt(5)).  It would
> be really good IMO if all of these were integrated to use just the
> Pythagorean distance, so only one system would be used.  This would be a
> problem from the ruleset's point of view since you would to need to use
> non-integer distances to represent most distances (or, alternately,
> conversions from the old system could be used like "vision=X" =>
> vision_radius=X*sqrt(2)).  The first step, though, is to implement the
> system.

If the pythagorean distance is used it has to be dense. This is to
prevent cases like if you get an increase by one and your current
vision is 2. 

index            | 0  1  2  3  4  5  6
square if radius | 0  1  2  4  5  8  9

I have no problem updating all the unit ruleset files.

I see no problem appling a patch which effectively leaves the game
like it is now but adds flexibility.

        Raimar

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