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Date: Mon, 3 Apr 2017 01:27:19 -0700 (PDT)
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Subject: Point size default
From: jacques.Lebourlot@obspm.fr
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Xref: csiph.com comp.graphics.apps.gnuplot:3609


(This was posted on "Gnuplot in Action" forum some time ago, but did not get any answer. I need it again...)

Point sizes are scaled from a "default" size, but I can't find the (terminal dependent) absolute value of this default. 

I wish to set a single point (pt 6) in a 3D splot to get a fixed circle of (physical) size 1, in the plane of the screen, when I change view with the mouse. This is to illustrate 3D coordinate systems (see the simplified example below). 

I managed to adjust the size by trial and error (45.5*sc below)), but it would be much more convenient to compute the scaling factor from known values. Hence, I need the default point size... 

Any idea? 

Thank you. 

Jacques 

PS: load the file interactively in gnuplot, then use the mouse to change view. The two blue circles (seen as ellipses) should stay tangent to the black one, whatever the view point.

Save the following code in a file.

-----------------------------------------------------------
# Optimized for interactive terminal (change view with the mouse)
set term wxt size 960, 576
set output

sc = 1.5

# Set a few global options
set angle degr
unset border
unset tics
set xran [-1.1:1.1]
set yran [-1.1:1.1]
set zran [-1.1:1.1]
set xyplane 0
set view equal xyz
set view 70, 110, sc

# Create a "heredoc" with the needed data
set print $M append
print "0.0 0.0 0.0"
print " "
do for [th = 0: 80: 1] {print cos(th*4.5), sin(th*4.5), 0.0}
print " "
do for [th = 0: 80: 1] {print 0.0, cos(th*4.5), sin(th*4.5)}

set arrow 1 from 0.0, 0.0, 0.0 to 0.0, 0.0, 1.25
set arrow 2 from 0.0, 0.0, 0.0 to 0.0, 1.25, 0.0
set arrow 3 from 0.0, 0.0, 0.0 to 1.25, 0.0, 0.0

splot \
      $M ever :::0::0 not w p lc rgb "black" pt 6 ps 45.5*sc, \
      $M ever :::1::1 not w l lt 6 lw 1, \
      $M ever :::2::2 not w l lt 6 lw 1
-----------------------------------------------------------