#                               -*- Mode: Sh -*- 
# antipodes_gmt  -- show antipodes
# Copyright       : http://www.fsf.org/copyleft/gpl.html
# Author          : Dan Jacobson -- http://jidanni.org/
# Created On      : Thu Jan  3 00:23:52 2002
# Last Modified By: Dan Jacobson
# Last Modified On: Wed Aug  4 10:35:10 2004
# Update Count    : 97
# Status          : just got it to work, haven't refined it yet

set -e
u="usage: $0 long lat width_in_degrees #center and width
$0 -5 40 6 for New Zelanders to visit their antipodes in Spain
$0 -157 21 7 Hawaii -- Botswana
$0 120 25 50 shows all of South American antipodes in Asia
$0 121.3 24.66 0.8 zooms in on Taiwan"
test $# -ne 3 && { echo "$u" >&2; exit 9;}
T=${file-tmp.ps}
set -- $(awk -v long=$1 -v lat=$2 -v width=$3 \
    "BEGIN{
if(width<=0){print \"$0: width <0\" >  \"/dev/stderr\";error=1}
if((long >= 0?long:-long)+width>180){
   print \"$0: frontside crossing int'l dateline causes problems at present\"\
        > \"/dev/stderr\";error=2} #don't know why, by the way 
     print long-width, long+width, lat-width, lat+width;
     print (long+360)%360, long+180 #meridian
     long+=180; lat*=-1;
     print long-width, long+width, lat-width, lat+width, error}")
test ! ${11}
R1=$1/$2/$3/$4 Q1=$5 Q2=$6 R2=$7/$8/$9/${10}
g=222/0/0; N=1 co=3/$g S=10c #need -W as -N3 won't give coastlines
: ${D=i}
gmtset BASEMAP_TYPE FANCY #PLAIN #PAPER_MEDIA B5+ 
#trap "rm $T" 0 #so copy the tmp file before you exit the viewer, if you want it
gmtset BASEMAP_FRAME_RGB $g
pscoast -JQ$Q1/$S $common -R$R1 -N$N/$co -D$D -P -W$co -K > $T
gmtset BASEMAP_FRAME_RGB 0/0/0
test "x$text1" != x && echo -e "$text1"|pstext -JQ$Q1/$S -R$R1 -O -K -G$g>> $T
test "x$text2" != x && echo -e "$text2"|pstext -JQ$Q1/$S -R$R1 -O -K >> $T
pscoast -JQ$Q2/$S -R$R2 -N$N -D$D -W -M|\
    awk '/^[0-9]/{$1+=180;$2*=-1};{print}'|\
    psxy -JQ$Q1/$S -R$R1 -M -O >> $T
gv $T

#Much thanks to Ben Horner-Johnson ben@rice.edu & Luis in France
#After I beef this up, perhaps someone should make an
#antipodes server...
#
#perhaps vary -D -A etc. according to the size of region selected

# b> Checking your script... skip the -P on the second pscoast command and the
# b> psxy command - once it is set with the first pscoast command, it has no
# b> function

#width=height too inflexible...