Hi Jerry:
I changed the subject line again since this is a separate issue from
antialiasing.
On 2008-11-18 22:05-0700 Jerry wrote:
> [...]I notice that in the SVG file, all of the tick marks are drawn
> twice.
I tried the following python test code in the installed examples/python
directory to confirm this issue.
#!/usr/bin/env python
# Append to effective python path so that can find plplot modules.
from plplot_python_start import *
import sys
from plplot import *
# Parse and process command line arguments
plparseopts(sys.argv, PL_PARSE_FULL)
# Initialize plplot
plinit()
pladv(0)
plvpor(0.1, 0.9, 0.1, 0.9)
plwind(0.1, 0.9, 0.1, 0.9)
plbox("bct", 0.7, 0, "bc", 0.7, 0)
# Terminate plplot
plend()
The resulting fragment of the svg file that draws one of the tick marks is
<polyline
stroke-width="1"
stroke="#FF0000"
stroke-opacity="1.000000"
fill="none"
points="503.98,54.01 503.98,63.46"
/>
<polyline
stroke-width="1"
stroke="#FF0000"
stroke-opacity="1.000000"
fill="none"
points="503.98,63.46 503.98,54.01"
/>
So it is clear the tick marks are drawn in one direction than redundantly in
the reverse direction confirming Jerry's remark. But if you look at the
svg.c code, there is no code to reverse the stroke or anything like that. So
the above redundant reverse stroke must be generated by the PLplot core
using a redundant call to plD_polyline_svg with just two points (more than
two points would generate a "points=" command with more than two points) or
else the equivalent redundant call to plD_line_svg (which always draws a
line between the two specified points).
In sum, these redundant reverse ticks appear to be generated in the PLplot
core and not the device code. Could somebody with more knowledge of the
PLplot core library than I have look further at this issue?
Also, notice how the XML format of the SVG results lends itself to
diagnosing Plplot core issues like this.
Alan
__________________________
Alan W. Irwin
Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).
Programming affiliations with the FreeEOS equation-of-state implementation
for stellar interiors (freeeos.sf.net); PLplot scientific plotting software
package (plplot.org); the libLASi project (unifont.org/lasi); the Loads of
Linux Links project (loll.sf.net); and the Linux Brochure Project
(lbproject.sf.net).
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