19.1.2  Graph and geometric objects attributes

There are two kinds of attributes for graphs and geometric objects: global attributes of a graphic scene and individual attributes for the specific geometric objects in the scene.

Individual attributes

Graphic attributes are optional arguments of the form display=value. They must be given as the last argument of a graphic instruction. Attributes are ordered in several categories: color, point shape, point width, line style, line thickness, legend value, position and presence. In addition, surfaces may be filled or not, 3D surfaces may be filled with a texture, 3D objects may also have properties with respect to the light. Attributes of different categories may be combined with +, e.g. in:

You can modify the following graphic attributes:

Color

which is set with display=value or color=value, where value is a nonnegative integer. See Section 19.1.3 for more details on colors. The predefined colors in Xcas are: black, white, red, blue, green, magenta, cyan, yellow, brown, purple, violet, pink, orange, grey, teal, olive, navy, and gold.

Point shape

which is set with display=value, where value can be one of: rhombus_point, plus_point, square_point, cross_point, triangle_point, star_point, point_point or invisible_point.

Point width

which is set with display=point_width_n, where n is an integer between 1 and 7.

Line thickness

which is set with thickness=n or display=line_width_n where n is an integer between 1 and 7.

Line shape

which is set with display=value, where value can be one of: dash_line, solid_line, dashdot_line, dashdotdot_line, cap_flat_line, cap_square_line or cap_round_line.

Legend

where the text is set with legend="legendname" and the position is set with display=value, where value is quadrantn for some n∈{1,2,3,4}. These values correspond to the position of the legend of the object (using the trigonometric plane conventions). The legend is not displayed if the attribute display=hidden_name is added.

Filling

which is set with display=filled.

Image texture

which is set gl_texture="picture_filename" and fills a surface with a texture. See the interface manual for a more complete description and for gl_material options.

Examples

(See Section 26.9.3, Section 26.5.2, Section 26.3.3 and Section 26.6.3 for information on the commands used.)

By entering

we get the same result as above.

Global attributes

The following attributes are pertinent to the scene as a whole:

• axes=true or axes=false shows or hides the axes. Alternatively, axes=a can be used, where a is a nonnegative integer. The following values have effect:
  • a=1: the same as axes=true.
  • a=0: the same as axes=false.
  • a=2: show only the relevant portion of the ordinate (used for bar plots).
  • a=3: show the outer frame/ticks but not the green and red inner axes (similar to Matlab).
  • a=4: same as a=3, but the ordinate ticks are not shown (used for drawing multi-channel waveforms and power spectra, where y-values are not meaningful or significant).
• title="titlename" sets the title.
• labels=["xname","yname","zname"] sets names of the x,y,z axes.
• gl_x_axis_name="xname", gl_y_axis_name="yname", gl_z_axis_name="zname" sets the names of the axes individually.
• legend=["xunit","yunit","zunit"] sets units for the axes.
• gl_x_axis_unit="xunit", gl_y_axis_unit="yunit", gl_z_axis_unit="zunit" sets units for the axes individually.
• gl_texture="filename" sets the background image to filename.
• gl_x=xmin..xmax, gl_y=ymin..ymax, gl_z=zmin..zmax sets the graphic configuration (do not use for interactive scenes)
• gl_xtick=xmark, gl_ytick=ymark, gl_ztick=zmark sets the tick marks for the axes.
• gl_shownames=true or gl_shownames=false shows or hides objects names
• gl_rotation=[x,y,z] defines the rotation axis for the animation rotation of 3D scenes.
• gl_quaternion=[x,y,z,t] defines the quaternion for the visualization in 3D scenes (do not use for interactive scenes).
• a few other OpenGL light configuration options are available but not described here.

Examples

Formatting textual annotations

There are several formatting options for the textual attributes (title, labels, and legend). Note that they can be used only in 2D plots.

• "*This is bold*" draws the text in a bold sans serif font.
• "/This is italic/" draws the text in an italic sans serif font.
• "$This is mathmode$" draws the text in a serif font and enables the following mathematical typesetting options:
  • ^int, where int is an integer, prints int in the exponent (also available outside math mode).
  • @char, where char is a letter, draws char with slanted font (useful for variables in formulas).
  • -- (double hyphen) prints as a minus sign − (which is different than the ordinary hyphen!).
  • <= resp. >= prints as ≤ resp. ≥.
  • +- resp. -+ prints as ± resp. ∓.
  • == prints as ≡.
  • != prints as ≠.
  •    prints as ≈.
  • \/ prints as √ . Note that the backslash must be escaped, i.e. entered as \\.
  • -> prints as →.
  • => prints as ⇒.
  • ** prints as ⋯ (vertically centered dots).
  • *, when preceded/followed by an alphanumeric character or parenthesis, is printed as · (the multiplication dot).
  • __ (double underscore) prints as — (em dash).
  • ^C prints as ^∘C.
  • ^F prints as ^∘F.

Note that changing font to bold, italic or serif typeface can only be applied to the entire text. The @-option uses special slanted Unicode symbols.

Example