STEP files for the masses (29 Jul 2009)

Every now and then, a CoCreate Modeling user needs some functionality which isn't in the product yet, or at least not precisely in the shape and form she needs it. For example, in a recent forum discussion, someone asked for a way to batch-convert CoCreate Modeling package files into STEP format.

The CoCreate Task Agent provides such functionality, but since it is an add-on module at extra cost, only some customers have it available to them. But that's no reason for despair, as it's pretty simple to add new functionality to the product.

Here's my take on the problem. My solution doesn't have any kind of glitzy UI, it doesn't handle errors, it's not optimized for performance - but it shows how the approach works, and that's all I wanted to accomplish.

;; (C) 2009 Claus Brod
;;
;; Demonstrates how to convert models into STEP format
;; in batch mode. Assumes that STEP module has been activated.

(in-package :clausbrod.de)
(use-package :oli)
(export 'pkg-to-step)

(defun convert-one-file(from to)
  (delete_3d :all_at_top)
  (load_package from)
  (step_export :select :all_at_top :filename to :overwrite)
  (undo))

(defun pkg-to-step(dir)
  "Exports all package files in a directory into STEP format"
  (dolist (file (directory (format nil "~A/*.pkg" dir)))
    (let ((filename (namestring file)))
      (convert-one-file filename (format nil "~A.stp" filename)))))

To use this code:

• Run CoCreate Modeling
• Activate the STEP module
• Load the Lisp file
• In the user input line, enter something like (clausbrod.de:pkg-to-step "c:/allmypackagefiles")

For each package (*.pkg) file in the specified directory, a STEP file will be generated in the same directory. The name of the STEP file is the original filename with .stp appended to it.

In pkg-to-step, the code iterates over the list of filenames returned from (directory). For each package file, convert-one-file is called, which performs the actual conversion:

Step	Command
Delete all objects in memory (so that they don't interfere with the rest of the process)	delete_3d
Load the package file	load_package
Save the model in memory out to a STEP file	step_export
Revert to the state of affairs as before loading the package file	undo

For each of those steps, we use one of the built-in commands, i.e. delete_3d, load_package, step_export and undo. (These are the kind of commands which are captured in a recorder file when you run CoCreate Modeling's recorder utility.) Around those commands, we use some trivial Common Lisp glue code - essentially, dolist over the results of directory. And that's all, folks

Astute readers will wonder why I use undo after the load operation rather than delete_3d the model. undo is in fact more efficient in this kind of scenario, which is an interesting story in and of itself - and shall be told some other day.

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