
########################
A3DCallbackProgressStart
########################

.. c:type:: A3DCallbackProgressStart

   A callback function the library invokes as it prepares to perform a potentially time-consuming process.
   
   The argument identifies the processing phase, as follows:
   
   **Processing phase** \| **Description**
   
   
   - 0 \| Undefined.
   - 1 \| Parsing the file
   - 2 \| Writing file
   - 3 \| Reading or building the model, which follows parsing the file (processing phase 1)
   
   
      2.0
   
   




