1. Introduction

The Boolean Operator of Open CASCADE (≤6.8.0) allows treating of two and only two arguments (shapes) to process [1]: S1 (Object), S2 (Tool). In modeling tasks the very frequent situation is when multiple shapes are to be processed from both sides, Object and Tool. For example, when we have to make in a body of Object multiple cutouts, we need to pass to the Boolean Operator one shape as the Object and a set of shapes as a Tool. The developer has to organize a cycle for repetitive cut from the Object shapes of the Tool one by one. Besides the fact that it is inconvenient for the developer, it applies additional extra expenses in the form of auxiliary temporary data structures that are filled in each instance of Boolean Operator.

2. Changes in Boolean Operator

In the current development version the Boolean Operator is able to treat two groups of arguments with arbitrary number of shapes, possibly having intersections with each other. The updated API takes on input a list of shapes on each side, Object and Tool. Each shape from the list meets usual requirements from [1]. The class BRepAlgoAPI_BooleanOperation contains the corresponding API for the usage of the new feature. The methods SetArguments(…), SetTools(…) provide the possibility to pass multiple arguments. The new feature of the Boolean Operator gives the following benefits:

• Possibility to perform the operation in a single pass
• Simplification of the caller procedure
• Improving the performance due to usage of one data structure
• Improving the whole performance for the cases with few number of actual intersections

3. Test Results

Testing of new functionalities has been performed for the cases where the old code had to be used in the mode of multiple sequential Boolean Operations, i.e. the result of one operation is the argument for the next one. The test results show the considerable improvement of the performance achieved by Boolean Operator with multiple arguments comparing with old sequential “two-arguments” approach. The following environment has been used to obtain the results below:

• Processor: IntelВ® Core(TM) i5-3450 CPU @ 3.10 GHz
• Installed memory (RAM): 16GB
• System type: 64-bit Operating System
• Operating System: Windows 7 Professional Copyright 2009 Microsoft Corporation. Service Pack1
• Compiler: Microsoft Visual Studio 2010 Version 10.0.40219
• Open CASCADE: 6.8.1 development, optimized mode
• All computations have been done in non-parallel (single-thread) mode

Example 3.1

The Figure 3.1.1 shows fragment of Objects (gold) and Tools (silver)

Figure 3.1.1

The parameters of the operation are in the Table 3.1.1

The performance values are in the Table 3.1.2

The fragment of the result is shown on the Figure 3.1.2

Figure 3.1.2

Example 3.2

The Figure 3.2.1 shows fragment of Objects (gold) and Tools (silver)

Figure 3.2.1

The parameters of the operation are in the Table 3.2.1

The performance values are in the Table 3.2.2

The fragment of the result is shown on the Figure 3.2.2

Figure 3.2.2

4. Conclusion

The Boolean Operator of Open CASCADE has been extended to be able to treat multiple arguments. The extended operator allows to:

• perform the operation at single pass
• simplify the caller procedure
• Improve the performance of the operator

5. References

1. OCCT 6.8.0 Boolean Operations User's Guide