[Freeciv-Dev] Re: (PR#7696) Re: Re: (PR#7637) Problem with line_width=2 [take 4]

["Raimar Falke" <i-freeciv-lists@xxxxxxxxxxxxx>]

<URL: http://rt.freeciv.org/Ticket/Display.html?id=7696 >

On Wed, Mar 10, 2004 at 11:37:45AM -0800, Jason Short wrote:
> > It is well define for line_width=1.
> 
> Right, but if you want to make 2 such calls you have to specify how 
> they're placed relative to each other.  This "defines" the size-2 line.
> 
> When drawing a sized-2 line around a tile, we draw 4 lines:
> 
>    (x0,y0) -> (x0, y0+H-1)
>    (x0,y0) -> (x0+W-1, y0)
>    (x0,y0+H-1) -> (x0+W-1, y0+H-1)
>    (x0+W-1,y0) -> (x0+W-1, y0+H-1)
> 
> but these lines should all be inset.  So instead of subtracting off 1 we 
> should subtract off 2 in most cases.  This is a situation where drawing 
> individual lines may give some advantage, because the inset does not 
> match exactly with the 2-line definition: think of it as two rectangles, 
> one inside the other, rather than as 4 double-width lines.  This is more 
> likely to make a difference in iso-view, where if you draw a 
> double-width line you may end up going 1 pixel over into the adjacent tile.

> But I'm not even sure the two-line method would work in iso-view.  Say 
> you draw two lines, from
> 
>    (x0,     y0 + H / 2) -> (x0 + W / 2, y0)
>    (x0 + 1, y0 + H / 2) -> (x0 + W / 2, y0 + 1)
> 
> can you guarantee that these lines will give the results you want?  Is 
> it possible there will be a hole between the two lines?  How could we 
> convince ourselves otherwise?

I face the same problem when I code gui-fs: where to draw the second
pixel. Since I don't see a nice solution I want that this decision is
moved up: in the common client code.

So somewhere we have to place the complexity of the decisions. Or we
remove it altogether by only allowing lines of odd width.

> I think the solution civ3 used was to provide sprites for the lines. 
> This allowed the lines to curve over hills and mountains (it took a 
> number of sprites, of course).

Or with this solution.

        Raimar

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