Re: [Gnuplot-info] how to draw a sphere that looks like a round sphere

[Thomas S. <t.s...@fz...>]

oh, what's that?
seems that there is an offset somehow reciprocal to the axis length.

this simple example shows the problem:

set view equal xyz
set xrange [-0.2:0.2]
set yrange [-1:1]
set zrange [-1:1]
splot sin(x**2+y**2)

has to do something with the calculation of 'xcenter3d', 'ycenter3d'
and 'zcenter3d' in 'graph3d.c'.
i'll try to find out how it works...


renzresearch wrote:
> 
> Thank you Thomas,
> 
> It works well for me.  One additional question: how does
> gnuplot decide the rotation center of a 3D object?  For
> example, if I do 'splot 0.2*cos(u)*cos(v), cos(u)*sin(v),
> sin(u)', the 3D oval swings from one side of my window to the
> other when I rotate it.  If I do 'splot 0.1*cos(u)*cos(v),
> cos(u)*sin(v), sin(u)', the object swings in and out of the
> window.  Can I specify a rotation center?
> 
> Zhong
> 
> 
> ---- Original message ----
>>Date: Fri, 22 May 2009 12:55:49 -0700 (PDT)
>>From: Thomas Sefzick <t.s...@fz...>  
>>Subject: Re: [Gnuplot-info] how to draw a sphere that looks
> like a round sphere  
>>To: gnu...@li...
>>
>>
>>start with a graphics window which is a square:
>>set term <terminal_type> size <XX>, <YY>
>>with XX = YY
>>
>>set view equal xyz
>>
>>set xyplane relative 0.0
>>
>>
>>renzresearch wrote:
>>> 
>>> The sphere I draw in parametric mode looks flattened in z
>>> direction, even I use 'set view equal xyz'.
>>> 
>>> I managed to use 'set view equal xy' and 'set view' to change
>>> scale and scale_z.  My sphere is now close to round.  The
>>> problem is that its vertical size keeps changing when I spin
>>> the sphere or resize the window.
>>> 
>>> Could someone give a hint?  There must be a simple option to
>>> make a sphere a perfect sphere no matter how you look at it.
>>> 
>>> Zhong
>>> 
>>>
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