[GRASS-dev] proper v.parallel behavior on strange input

[Росен Матев]

Hi,

Ok, I'll try to figure out how to generate such looped parallel line.
I'll note again that my algorithm, which generates non-looped parallel
lines (like the ones that should be generated when making buffers),
does not go through stage, in which there are loops. Therefore,
generating those looped lines will need another separate algorithm
(with some familiarities, but not much).

Rosen

On Mon, May 26, 2008 at 11:14 PM, Marco Alicera <marco.alicera at gmail.com> wrote:
> Hi,
>
> IMHO, the wolf`s approach is the good one, since  the 'proper'
> parallel line must be choosen by users.
>
> i prefere it because it is flexible and can be very fast if there is
> no need to remove the loop or no loop are expected.
>
> marco
>
> 2008/5/26, Росен Матев <r.matev at gmail.com>:
>> Hi Wolf,
>>
>>  The thing that bothers me is the upper line segment of the loop. It's
>>  parallel to the corresponding segment of input line but it's direction
>>  is the opposite. That is quite "non-algorithmic".
>>  By the way, I'm pretty sure that I figured out an algorithm, which
>>  will create 'proper' parallel line  s (without loops as in Wolf's
>>  non-dashed example). Unlike the old method of creating parallel lines
>>  with loops and then cleaning the mess, my algorithm works in one
>>  piece. (I think the old method doesn't work because you cannot remove
>>  the loops properly by only using the line-with-loops itself)
>>
>>  Rosen
>>
>>
>>  On Mon, May 26, 2008 at 9:15 PM, Wolf Bergenheim
>>  <wolf+grass at bergenheim.net> wrote:
>>  > Hi!
>>  >
>>  > IMHO it should loop back, and by default the loop should be detected and
>>  > removed. An option to not remove the loop could be cool.
>>  >
>>  > See attached image. The part that should be removed is drawn with a dashed
>>  > line.
>>  >
>>  > --Wolf
>>  >
>>  > On 26.05.2008 15:02, Росен Матев wrote:
>>  >>
>>  >> Hello,
>>  >> I'm currently reimplementing v.parallel/v.buffer. There are some
>>  >> strange inputs with no apparent behavior. Please suggest what should
>>  >> v.parallel do on such inputs.
>>  >> I've attached a simple input. Try to make a parallel line on right
>>  >> side of the given line; distance is greater than 5m (let's say 7m).
>>  >>
>>  >>
>>  >> ------------------------------------------------------------------------
>>  >>
>>  >>
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>>  > --
>>  >
>>  > <:3 )---- Wolf Bergenheim ----( 8:>
>>  >
>>  >
>>
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