Re: [ gnuplot-Patches-1218873 ] Change text rotating angle from int to float

[Ethan A M. <merritt@u.washington.edu>]

On Sunday 23 October 2005 03:00 pm, Harald Harders wrote:
> float a = 0.0;
> if (a == 0) ...
>
> always is true? I don't think so. 

IEEE standard guarantees this.  Even in the case that an architecture
can represent both +0 and -0,  it is required that +0 == -0.

Yes, I know that not all C compilers require IEEE floating point.
But I am inclined to say that if your compiler is so broken that
it fails to store 0 as 0, then using it to build gnuplot will reveal
bigger problems than accurate text rotation :-) 

>> The only place a rotation angle gets set is in parse_label_options().
> I find more: 3555, 4020

True. This may be telling us that these places 
("set tics" and "set {xyz}tics") should call parse_label_options()
rather than duplicating the code locally.

> Sooner or later, this will also have to be added in line 3715 (by the
> way, funny that there still are texts not rotatable by arbitrary
> angles).

You want to rotate the time-stamp?  That seems a little bit overboard.
If you really want to write the data on a plot in a fancy font or
rotated text, you can easily use some variant of   set label "`date`".

> Another thing could be thought of:
> Terminals that can only set term horizontally or vertically should
> switch from horizontal to vertical text when exceeding 45 degrees, not
> when going from zero to one. What do you mean?

I think that if someone really wants 45 degree text, they will be
equally unhappy with either 0 or 90.

> And we really should find out which terminals are capable of arbitrary
> text angles but do not use it right now.

Sure. I originally added it to all the terminal types I could test
at the time. And there's a patch on SourceForge that adds it to metapost.
But there remain other terminal types I cannot test, or I do not have
documentation for their output device capabilities.

-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742