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off_color - add colours to an OFF file

Usage    |    Examples    |    Notes

Usage



Usage: off_color [options] [input_file]

Read a file in OFF format and add colours to it. If input_file is
not given the program reads from standard input.

A colour value can be a single integer (a colour index), a value in
form 'R,G,B,A' (3 or 4 values 0.0-1.0, or 0-255) or hex 'xFFFFFF', a
colour name from the X11 colour map, 'invisible' or 'none' (which sets
without any colour information)

Lowercase letters (except l) colour using index numbers and uppercase
letters colour using colour values. Symmetric colourings are optionally
followed, separated by commas, by a subsymmetry (Schoenflies notation)
and a conjugation type (integer). Adjacent element colourings FEV are
processed after other element colourings, and in the order -f, -e, -v.

Options
  -h,--help this help message (run 'off_util -H help' for general help)
  --version version information
  -f <col>  colour the faces according to:
               a colour value - apply to all faces
               u,U - unique colour
               p,P - minimal proper colouring
               s,S - symmetric colouring [,sub_group,conj_type] (see above)
               n,N - colour by number of sides
               a,A - colour by average internal angle (to nearest degree)
               k,K - sets of faces connected by face edges
               E   - colour with average adjacent edge colour
               V   - colour with average adjacent vertex colour
               g,G - gradient on z-coordinate of normal
               c,C - gradient on z-coordinate of centroid
               L   - lighting effect by normal (see option -l)
               l   - lighting effect by centroid (see option -l)
               M   - use colour map to convert existing colour index numbers
                     into to values
  -E <type> colour by edge type, e - explicit edges, i - implicit edges
            I - implicit edges which are not explicit edges (default: if -e
            explicit and implicit, else explicit for mapping only)
  -e <col>  colour the edges according to:
               a colour value - apply to all edges
               u,U - unique colour
               p,P - minimal proper colouring
               s,S - symmetric colouring [,sub_group,conj_type] (see above)
               n,N - colour by number of faces connected to each edge
               k,K - sets of edges connected by edges
               F   - colour with average adjacent face colour
               V   - colour with average adjacent vertex colour
               d,D - colour by edge direction
               j,J - color by edge length [,minimum_difference (def: 1e-6)]
               g,G - gradient on z-coordinate of edge direction
               c,C - gradient on z-coordinate of centroid
               L   - lighting effect (see option -l)
               l   - lighting effect on edge directions (see option -l)
               M   - use colour map to convert existing colour index numbers
                     into to values
  -v <col>  colour the vertices according to:
               a colour value - apply to all vertices
               u,U - unique colour
               p,P - minimal proper colouring
               s,S - symmetric colouring [,sub_group,conj_type] (see above)
               n,N - colour by order of vertex
               a,A - colour by avg internal ang of vert-fig (to nearest deg)
               F   - colour with average adjacent face colour
               E   - colour with average adjacent edge colour
               c,C - gradient on z-coordinate
               L   - lighting effect (see option -l)
               M   - use colour map to convert existing colour index numbers
                     into to values
  -l <file> lights for colouring type L in a file in OFF format, each
            vertex and its colour gives a light direction and colour
            (default: a set of six lights giving a rainbow colouring)
  -m <maps> a comma separated list of colour maps used to transform colour
            indexes (default: spread), a part consisting of letters from
            v, e, f, selects the element types to apply the map list to
            (default 'vef').
  -r <rnge> Map HSVA values onto the specified HSVA ranges after other
            processing (but before -I), component letters are followed by
            one or two values separated by a colon e.g H0.5:0.8 followed by
            a comma and elements to map from v, e, f (H0:1S0:1V0:1A0:1,vef)
  -I <elms> map color values to index numbers (after other procesing)
            elements to map are from v, e and f (default none)
  -w <wdth> width of sphere containing points (default: calculated)
  -U <typs> colour only elements with particular current colour types:
            u - unset, i - indexed, v - visible colour value, x - invisible.
            ~ before the letter will select the opposite.
  -o <file> write output to file (default: write to standard output)

Examples

Make a cuboctahedron with the triangle faces a different colour to the square faces
off_color -f N cuboctahedron | antiview


Same again, but make the colours black and white. Create a file called my_colormap.txt with these two lines, which convert colour index numbers into colour values. With -f N, faces are assigned a colour index number the same as the number of sides, and this is then mapped to a colour value by the active colour map.
   3 = 0.0 0.0 0.0
   4 = 1.0 1.0 1.0
Now the command is
off_color -f N -m my_colormap.txt cuboctahedron | antiview


Even easier, create the colour map on the command line, with component values or names
off_color -f N -m map_3=0.0/0.0/0.0:4=1.0/1.0/1.0 cuboctahedron | antiview
off_color -f N -m map_3=black:4=white cuboctahedron | antiview


Colour faces with unique colours
off_color -f U geo_2 | antiview -x ve


Make dark colours for U by decreasing the value of the default map
off_color -f U -r V0.4 geo_2 | antiview -x ve


Rather than changing a map with -r an map with the desired colours could be chosen e.g. a map with blue-green range and a pastel range
off_color -f U -m rnd_H0.4:0.7 geo_2 | antiview -x ve
off_color -f U -m rand_S0.3 geo_2 | antiview -x ve


Colour different elements with different maps
off_color -f U -m f,rnd_H0.4:0.7 -e U -m e,rnd_H0.9:1.2 geo_2 | antiview -v 0.05


Colour edges and vertices with a rainbow effect
off_color -f 1.0,1.0,1.0 -e L -v L geo_5 | antiview -v 0.05


Make a lights file placing a red, green, blue and white light tetrahedrally, call it lts.off
OFF
4 4 0
1 1 1
1 -1 -1
-1 -1 1
-1 1 -1
1 0 255 0 0
1 1 0 255 0
1 2 0 0 255
1 3 255 255 255
Colour faces with a lighting effect using these lights
off_color -l lts.off -f L geo_5 | antiview -x ve


Notes

A selection of lights files and colour map files are included with the Antiprism resources. More colour maps are available from Colorzilla Palettes.

Proper colourings are not always optimal.

Face colourings G and L which use normals are affected by the orientation of the faces. If the colouring is patchy then orient the faces with off_util -O pos

See also off_color_radial for a symmetric colouring method.


     Next: off_color_radial - radial colouring based on symmetry
     Up: Programs and Documentation


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Contact: adrian@antiprism.com      -      Modified 6.1.2021