Week #21 – Creating and Customizing Library Parts
21-2. Making a 2D Symbol More Parametric with Simple GDL Editing

ArchiCAD Training (Best Practices Lesson 21-2)

This ArchiCAD training is the second in a three part series on creating custom objects for the ArchiCAD library.

In this 15 minute video, we look at how to make a 2D symbol more flexible by adding a parameter to control the size of the text and doing some simple editing of the GDL script. The result is a symbol that can be used with different font sizes depending on the context.

The text size is specified within the GDL script in units of millimeters. The common standard (in the U.S. and some other parts of the world) is to specify font sizes in points.

Here’s how you can convert points to mm:

  • There are 72 points in an inch
  • 25.4 mm = 1 inch
  • Example: 7 point text = 7/72 inch = 7/72 * 25.4 mm = 2.47 (mm)
  • Formula: text size in mm = (text size in points) / 72 * 25.4

A variation of the 2D symbol is created with two lines of text. The break between the lines is caused by hitting the Return or Enter key on the keyboard, which actually creates a “paragraph break”. When the new object is saved, you will see that each “line” of text is actually a separate paragraph within the GDL script.

Separate parameters can be set up for each line (paragraph) of text, as well as for the text size in mm (or in points, as long as the script is set up with the formula above). Note that each text parameter (each line or paragraph) may be up to 256 characters in length – which should be more than enough for basic 2D symbols.

Thank you for visiting the Best Practices Course website. The video lessons are available for members only. If you are an active member and would like to watch the ArchiCAD training video on this page, please login to the website. If you are not currently a member, please visit the following pages for more information and to sign up for the Best Practices Course, the QuickStart Course or for the Best Practices ArchiCAD Coaching Program. Eric Bobrow, Creator of the Best Practices Course
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ArchiCAD Training: Making a 2D Symbol More Parametric with Simple GDL Editing

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  1. Avatar photo
    10 years ago

    This was very helpful Eric!

    I just went through both parts of this tutorial and created my own room label symbol w/ parametric room names and numbers with adjustable text sizes. This is kind of what I was after when we discussed this last week. The one detail I am still fussing over, and this also true if I use the zone tool: I typically put the room number in a rectangular box below the room name, and when I do that here the box does not adjust to the length of the number text and instead remains generically much longer. Is there any way to control this in the parameter dialog? I can send a screen shot if that helps.

  2. Roderick Anderson
    11 years ago

    This was right up the alley of what I needed. Maybe one small detail that maybe you did not think of when creating the video is how to make sure that when an object I create is rotated that the text stays horizontal? I’m sure there is something in the script that determines this.

    For example, I have created a symbol for a wall-mounted sconce, so I created it drawn as if it were mounted on a wall on the left side, but if I rotate the object for the other side of the room then the text is upside down. How can I correct this?