File Formats and Templating

Unless defined otherwise in the command help (geomdl-cli {command} --help), any command in need of a NURBS data input usse the following file formats: libconfig, YAML and JSON. Please see geomdl documentation for details on the supported file formats.

Using Jinja2 templates in input files

The following YAML file describes a 3-dimensional Bézier curve:

{% set degree = 3 %}
{% set kv = knot_vector(3, 4) %}

shape:
  type: curve
  data:
    degree: {{ degree }}
    knotvector: {{ kv }}
    control_points:
      points:
        - [10, 5, 10]
        - [10, 20, -30]
        - [40, 10, 25]
        - [-10, 5, 0]

The tags {% and %} define Jinja2 template statements, {{ and }} define expressions to print to the template output. {% set degree = 3 %} simply creates a template variable degree which can be used to replace integer 3. This variable is used to set the curve degree with {{ degree }}.

knot_vector is a wrapper for utilities.generate_knot_vector function. {% set kv = knot_vector(3, 4) %} sets the output of the template function to the template variable kv.

The following is the list of custom template functions supported by geomdl-cli:

• knot_vector(d, np): generates a uniform knot vector. d: degree, np: number of control points
• sqrt(x): square root of x
• cubert(x): cube root of x
• pow(x, y): x to the power of y