Tutorial - Semi-automatic parametrization of a DXF file

Let’s learn by example.

In this tutorial, we will learn how to semi-automatic parametrize a DXF file.

We’ll assume you have QSketchMetric installed already as well as QCAD Professional and have already done the rendering tutorial as well as parametrization tutorial

First download the tutorial_param.dxf file from the QSketchMetric repository. It is an example of a DXF file that we will parametrize in this tutorial. It is a simple drawing of a chalice. With every entity placed on the CUTTING layer.

To do so, open it and click Ctrl+S to save it to your computer. As a convention, we’ll assume you saved it in a file called tutorial_param.dxf.

Let’s start by firing up command line and starting the python interpreter:

python

Warning

Remember to activate your virtual environment if you are using one:

source .venv/bin/activate

Next we need to import the qsketchmetric.semiautomatic.SemiAutomaticParameterization module:

from qsketchmetric.semiautomatic import SemiAutomaticParameterization

Now define the path to the input file we downloaded earlier:

input_dxf_path  = "tutorial_param.dxf"

For the output file path and default parameter we will use default settings.

Now we are ready to roll. Let’s parametrize the DXF file:

sap = SemiAutomaticParameterization(input_dxf_path)
sap.parameterize()

Parametrized file will be saved in the parametric directory, in the same directory as the input file.

Open the parametrized file in QCAD Professional, and edit the parameters.

Every entity parameter is now set to the default parameter. Let’s change their values.

To do so select the entities one by one and scroll down the Property Editor to the Custom section. Click on c parameter to edit it.

Value contains the expression describing the entity. According to this table below:

Value	Description
c	(constant) Entity length will not change
?	(undefined) Entity length will be calculated by the renderer. Only if there is other path to the both end points of the line!
c*2/5	(math expression) Entity length will be calculated from the math expression

You can change the value of the parameter to any of the above. For example, let’s change the value of the

chalice leg line to 2*c. This will make the leg line 2 times longer.

Lastly, we check if the parametrization is correct by validating it. To do so, follow the Validation your first DXF file tutorial.

That is it! You have successfully parametrized a DXF file. As you can see semi-automatic parametrization is much faster and easier than manual parametrization.

Congratulation!