| Re: starting point of dashed lines [message #65725] |
Mon, 23 March 2009 07:54  |
Jeremy Bailin
Messages: 618
Registered: April 2008
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Senior Member |
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On Mar 23, 10:22 am, Paolo <pgri...@gmail.com> wrote:
> Hi Jeremy,
>
> yes, this is one of the things I dislike about plot,
> that such details as the phase of dashes is totally
> out of control.
>
> In fact, at some point I wrote a little procedure to
> overplot with dashes of specified length and phase...
> I should still have it I believe, and I can dig it up for
> you if that would be useful...
>
> Ciao,
> Paolo
>
> Jeremy Bailin wrote:
>> On Mar 22, 12:28 pm, Jeremy Bailin <astroco...@gmail.com> wrote:
>>> Any sort of dashed and/or dotted linestyle (i.e. anything other than
>>> linetsyle=0) has some natural "starting point" or phase. Is there a
>>> way to manually reset it?
>
>>> My specific problem is that I'm generating some plots in .png files
>>> that are going to be stuck together as an animation, including a
>>> dashed line that should be identical in each plot. However, it isn't -
>>> at least, not when plotted to the Z buffer! Here is some code that
>>> demonstrates this:
>
>>> set_plot, 'z'
>>> plot, [0,1], [-0.5,0.5]
>>> erase
>>> oplot, [0,1], [0,0], lines=2
>>> write_png, 'test1.png', tvrd()
>>> erase
>>> oplot, [0,1], [0,0], lines=2
>>> write_png, 'test2.png', tvrd()
>
>>> If you compare the two .png files, you'll see that the dashing is
>>> shifted slightly. However, if I do this with set_plot,'x' instead, it
>>> works fine!
>
>>> -Jeremy.
>
>> Incidentally, the easiest way to see this is to omit the second
>> "erase" command in my example - then the actual size of the dashes
>> appears to get bigger as out-of-phase dashes get overplotted on top of
>> each other.
>
>> Anyone?
>
>> -Jeremy.
>
>
Would love it. I've worked around this particular issue today by using
a gray line instead, but I can easily see it coming up again.
What bugs me is that there must be *some* internal variable that is
telling IDL what phase to start at. So how can we get at it??
-Jeremy.
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