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mirror of https://git.dev.opencascade.org/repos/occt.git synced 2025-04-04 18:06:22 +03:00
msv e1c1b6b9f4 0027490: BRepMesh: Reduce number of memory allocations
1) Reduce the number of calls to malloc by grouping requests to larger blocks. To achieve this goal, the following ways are used:

- Containers of types sequence, list and map are initialized with an instance of NCollection_IncAllocator, at this taking care of the time of life of allocated objects, so that not to occupy huge amount of memory.

- Allocation of several arrays having the same and short life time is changed so that to allocate a buffer array of necessary size and to place arrays in this buffer.

2) In BRepMesh_FastDiscretFace, optimize the function filterParameters so that to avoid excess memory allocations.

3) In NCollection_CellFilter, change declaration of the method Reset to accept array by reference rather than by value.

4) Add Allocator() method in map, sequence and vector collection classes by analogy with list collection.

5) Correct the size of block for IncAllocator for x64 platform. In order free-ed block to be returned to the system its size should be at least 1024K on x64 and 512K on x86. This allows to retain free virtual space almost to the state before algorithm run.

6) Decrease amount of memory zeroed by calloc. For that, reduce theIncrement parameter of the embedded vectors of the classes NCollection_UBTreeFiller and BRepMesh_VertexInspector to default value 256.

7) Avoid computing bounding box when not necessary (if no relative deflection is used)

8) Cycles by wires of face using TopExp_Explorer are converted to use TopoDS_Iterator instead.

9) BRepMesh_FastDiscret::Add optimized to avoid storing sequences of faces and edges

10) The tests "mesh standard_* W7" are corrected to accept the new behavior. Earlier the following error took place:
Not connected mesh inside face 9
{12 13}
Now this error was replaced with another one:
free nodes (in pairs: face / node):
{9 12}
Actually it is not a regression, rather improvement, if we look at the snapshot.

11) Change other test cases to their actual state.
2016-05-13 19:04:34 +03:00

Open CASCADE Technology
=======================

This directory contains sources of Open CASCADE Technology (OCCT), a software
development platform providing services for 3D surface and solid modeling, CAD 
data exchange, and visualization. Most of OCCT functionality is available in 
the form of C++ libraries. OCCT can be best applied in development of software 
dealing with 3D modeling (CAD), manufacturing / measuring (CAM) or numerical 
simulation (CAE).

License
-------

Open CASCADE Technology is free software; you can redistribute it and / or 
modify it under the terms of the GNU Lesser General Public version 2.1 as 
published by the Free Software Foundation, with special exception defined in 
the file OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included
in OCCT distribution for complete text of the license.

Alternatively, Open CASCADE Technology may be used under the terms of Open 
CASCADE commercial license or contractual agreement.

Note that Open CASCADE Technology is provided on an "AS IS" basis, WITHOUT 
WARRANTY OF ANY KIND. The entire risk related to any use of the OCCT code and 
materials is on you. See the license text for formal disclaimer.

Packaging
---------

You can receive certified version of OCCT code in different packages.

- Snapshot of Git repository: contains C++ header and source files of OCCT,
  documentation sources, build scripts, and CMake project files.

- Complete source archive: contains all sources of OCCT, generated HTML and PDF
  documentation, and ready-to-use projects for building on all officially 
  supported platforms.

- Binary package (platform-specific): in addition to complete source archive, 
  it includes binaries of OCCT and third-party libraries built on one platform. 
  This package allows using OCCT immediately after installation.

Certified versions of OCCT can be downloaded from http://www.opencascade.com

You can also find OCCT pre-installed on your system, or install it from 
packages provided by a third party. Note that packaging and functionality
of such versions can be different from certified releases. Please consult 
documentation accompanying your version for details.

Documentation
-------------

Open file doc/html/index.html to browse HTML documentation.

If HTML documentation is not available in your package, you can:

- Generate it from sources. 

  You need to have Tcl and Doxygen 1.8.4 (or above) installed on your system.
  and accessible in your environment (check environment variable PATH).
  Use batch file *gendoc.bat* on Windows or Bash script *gendoc* on Linux
  or OS X to (re)generate documentation.

- Read documentation in source plain text (MarkDown) format found in 
  subfolder *dox*

See *dox/dev_guides/documentation/documentation.md* for details.

Building
--------

In most cases you need to rebuild OCCT on your platform (OS, compiler) before
using it in your project, to ensure binary compatibility.

Consult the file *dox/dev_guides/building/building.md* for instructions on
building OCCT from sources on supported platforms.

Version
-------

The current version of OCCT can be consulted in the file
*src/Standard/Standard_Version.hxx*

Development
-----------

For information regarding OCCT code development please consult the official 
OCCT Collaborative Development Portal:
http://dev.opencascade.org
Description
Mirror of OpenCascade OCCT, at https://git.dev.opencascade.org/repos/occt
Readme 167 MiB
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