#
# Polygons as individual objects first,
# then "splot with polygons"
#
# The vertices of an icosahedron are circular permutations of (0, ±1, ±ϕ)
# where    ϕ = (1 + √5) / 2    is the golden ratio.

phi = (1.0 + sqrt(5.)) / 2.

array v1 = [0., 1., phi]
array v2 = [0., 1., -phi]
array v3 = [0., -1., phi]
array v4 = [0., -1., -phi]
array v5 = [ 1., phi, 0.]
array v6 = [ 1., -phi, 0.]
array v7 = [ -1., phi, 0.]
array v8 = [ -1., -phi, 0.]
array v9  = [ phi, 0., 1.]
array v10 = [ -phi, 0., 1.]
array v11 = [ phi, 0., -1.]
array v12 = [ -phi, 0., -1.]

# define one point per vertex
do for [i=1:12] {
    eval( sprintf("set label %d 'v%d' at v%d[1], v%d[2], v%d[3]", i,i,i,i,i ))
}

seq1 = "v5 v7 v10 v3 v9 v5"
n = 1
do for [i=1:5] {
    vert1 = word(seq1,i)
    vert2 = word(seq1,i+1)
    eval( sprintf("set obj %d polygon from v1[1], v1[2], v1[3] to %s[1],%s[2],%s[3] to %s[1],%s[2],%s[3]", n, vert1, vert1, vert1, vert2, vert2, vert2) )
    n = n+1
}

seq2 = "v5 v11 v4 v12 v7 v5"
do for [i=1:5] {
    vert1 = word(seq2,i)
    vert2 = word(seq2,i+1)
    eval( sprintf("set obj %d polygon from v2[1], v2[2], v2[3] to %s[1],%s[2],%s[3] to %s[1],%s[2],%s[3]", n, vert1, vert1, vert1, vert2, vert2, vert2) )
    n = n+1
}

seq3 = "v3 v10 v12 v4 v6 v3"
do for [i=1:5] {
    vert1 = word(seq3,i)
    vert2 = word(seq3,i+1)
    eval( sprintf("set obj %d polygon from v8[1], v8[2], v8[3] to %s[1],%s[2],%s[3] to %s[1],%s[2],%s[3]", n, vert1, vert1, vert1, vert2, vert2, vert2) )
    n = n+1
}

    eval( sprintf("set obj %d polygon from v7[1], v7[2], v7[3] to v12[1],v12[2],v12[3] to v10[1],v10[2],v10[3]", n) )
    n = n+1
    eval( sprintf("set obj %d polygon from v6[1], v6[2], v6[3] to v4[1],v4[2],v4[3] to v11[1],v11[2],v11[3]", n) )
    n = n+1
    eval( sprintf("set obj %d polygon from v5[1], v5[2], v5[3] to v9[1],v9[2],v9[3] to v11[1],v11[2],v11[3]", n) )
    n = n+1
    eval( sprintf("set obj %d polygon from v9[1], v9[2], v9[3] to v6[1],v6[2],v6[3] to v11[1],v11[2],v11[3]", n) )
    n = n+1
    eval( sprintf("set obj %d polygon from v9[1], v9[2], v9[3] to v3[1],v3[2],v3[3] to v6[1],v6[2],v6[3]", n) )
    n = n+1

set for [o=1:n] obj o polygon depthorder fs transparent solid 0.8 fc "gray75"
set pm3d depthorder border lc "black" lw 2

set xrange [-2:2]; set yrange [-2:2]; set zrange [-2:2]
set view equal xyz
set view 30,30,1.5
unset border
unset tics
unset key
unset label
undefine v*
undefine seq*

set title "Faces of an icosahedron drawn as 20 individual objects"
splot -10

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set title "2-sided coloring\ngreen outside, yellow inside"
set style line 101 lc "forest-green" 
set style line 102 lc "goldenrod" 
set for [o=1:n] obj o polygon depthorder fs transparent pattern o fc ls 101
replot


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unset object
set pm3d lighting spec2 0.6

set title "splot icosahedron.dat with polygons"

splot 'icosahedron.dat' with polygons fc "gray75"


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set title "splot dodecahedron.dat with polygons"
set view 148, 55, 2.7
set pm3d lighting spec2 0.3

splot 'dodecahedron.dat' with polygons fc "gold"


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set title "splot truncated_cube with polygons" noenhanced
set view 36, 60, 4.2
set style fill transparent solid 0.75
set pm3d nolighting border lt -1 lw 2

splot 'truncated_cube.dat' using ($1-0.5):($2-0.5):($3-0.5) with polygons fc bgnd


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set title "A whale rendered as a fan of large polygons"
set view 59, 314, 3.0, 1.0
set view  equal xyz
set pm3d depthorder 
set pm3d border linecolor rgb "blue"  linewidth 0.25
set autoscale

splot 'whale.dat' using 1:2:3 with polygons fc "slategray", \
      'whale.dat' with lines lw .2 lt 6


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