Syntax

   FACTORY_DEF <ReaderKeyword> CSGFactory 
   [FACTORY_NAME <factory name>] 
   [INPUT (A|B) FEATURE_TYPE <factory type>
   [<attribute name> <attribute value>]* 
   [<feature function>]*]*
   [GROUP_BY [<attribute name>]+] 
   [OUTPUT (UNION|DIFFERENCE|INTERSECTION|UNUSED) * FEATURE_TYPE <feature type>
   [<attribute name> <attribute value>]*
   [<feature function>]*]* 

Overview

   The CSGFactory performs Union, Difference and Intersection Boolean operations 
   on a solid geometry feature from input A against another solid geometry 
   feature from input B, and outputs the result through the output tags UNION, 
   DIFFERENCE and INTERSECTION respectively. The output is a feature with a CSG 
   solid geometry.

   The factory only takes one solid feature from each input A and B. Any extra 
   features or non-solid features are output through the UNUSED tag. It does not 
   output anything through UNION, DIFFERENCE and INTERSECTION tags unless it can 
   find one solid feature from each input tag. 

   The GROUP_BY clause can be used to perform a Boolean operation for a pair of 
   solids (one from each input tag) that has the same attributes specified by 
   this clause.

Output Tags

   The CSGFactory supports the following output tags.

   UNION 
      
      Result of solid A union with solid B.

   DIFFERENCE  
   
      Result of solid A minus solid B.

   INTERSECTION   
   
      Result of solid A intersects with solid B.

   UNUSED   
   
      Features that are rejected by the factory.