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.

This post in devoted to improvement of performance of building part of Boolean operations. Though in most cases the most time-consuming is intersection part (89% of overall time spent for BO by all Open CASCADE tests), there are special cases where building part takes most of the time. As an example the test case perf bop boxholes is taken, in which relation between Intersection and Building Parts is 2.85 / 26.16. This case is remarkable for showing the performance of the modeler when working with big number of simple shapes.

Next version of OCCT will feature new mode of Boolean Operation Algorithm (BOA), called "Fuzzy". Fuzzy Boolean operations are the type of Boolean operations in which additional user-specified tolerance is used. This mode allows Boolean operations to handle robustly cases of touching and near-coincident entities of the argument shapes.

Hello All,

The release of OCCT 6.8.0 is published. The corresponding tag in Git is "V6_8_0". Note that WOK has also been changed, its version is also elevated to 6.8.0.

Starting from version 6.8.0 OCCT will include one more algorithm for solving global optimization problems.

Its development has been triggered by insufficient performance and robustness of the existing algorithm of minimization of curve - surface distance in Extrema package (class Extrema_GenExtCS). Recent attempts to fix problems in that algorithm led to severe reduction of its performance, hence the need of a different approach raised.

Few months ago, the OCCT ray tracing algorithm was rewritten using GLSL. Apart from better portability and certain performance gain, this step opened the door to some important features that can be added most naturally using close OpenGL and GLSL interoperation - such as visualization of lines and text in a ray-traced scene. Lines and text are examples of scene elements that cannot be visualized using purely the ray tracing algorithm.

Hello,

We are steadily progressing in the refactoring tasks, and now have the first version of OCCT without WOK and CDL ready for review: see Git branch CR0_noCDL.
Note that this is the first experimental version, thus please do not try to use it in your project!

Here is some detail on the changes made in this branch.

Starting with version 6.8.0 OCCT will have a new algorithm for solving global optimization tasks using an arbitrary objective function of several variables on a hyperparallelepiped.

The algorithm is based on a slightly modified method of searching the global extremum of a function of several variables satisfying the Lipschitz condition [1, 2].

Run-Time Type Information (RTTI) is C++ mechanism to access type information in code at runtime, including well-known dynamic_cast operator. Although this functionality is integral part of modern C++ standard, this was not true at OCCT foundation time. This is why OCCT has been designed with own RTTI implementation.

Since any modern C++ compiler has built-in RTTI support, many users complain - why OCCT still uses their own implementation? Well, migration to built-in C++ mechanisms would require significant changes due to design differences. However this article covers another aspect of such possible migration - performance comparison.