GEOMLib - 3D CSG Geometry Library for MATLAB® and GNU Octave

GEOMLib is a 2D and 3D geometry library for MATLAB® and GNU Octave allowing mesh based CSG (Composite Solid Geometry) operations.

Originally developed for use with the FEATool Multiphysics FEA simulation toolbox, but now replaced with the OpenCASCADE geometry kernel to support BREP CAD geometry support.

Installation

Download and copy the library to a folder. Start MATLAB® or Octave and start the runtests script (or runtests 1 for verbose output) to run the test and validation suite.

Examples

1. 2D example of the union of a circle and unit square

    % Create circle
    c1 = gobj_circle([0, 0], 0.5, 'C1');
    c1 = convert_gobj_polygons( c1, 1 );
    c1 = csg_op( c1, 'b' );
   
    % Create unit square
    r1 = gobj_rectangle(0, 1, 0, 1, 'R1');
    r1 = convert_gobj_polygons( r1, 2 );
    r1 = csg_op( r1, 'b' );
   
    % Join circle and square
    [res,~,stat] = csg_op( c1, r1, '+' );
   
    % Visualize result
    csg_op(res, 'v')
   

2. 3D subtraction of a sphere from a unit cube

    % Create sphere
    s1 = gobj_sphere([0, 0, 1], 0.5, 'S1');
    s1 = convert_gobj_polygons( s1, 1 );
    s1 = csg_op( s1, 'b' );
   
    % Create unit cube
    b1 = gobj_block(0, 1, 0, 1, 0, 1, 'B1');
    b1 = convert_gobj_polygons( b1, 2 );
    b1 = csg_op( b1, 'b' );
   
    % Subtracting sphere from cube
    [res,~,stat] = csg_op( b1, s1, '-' );
   
    % Visualize result
    csg_op(res, 'v')
   

3. For more examples see the tests in the test directory.

Functions

% Main CSG functions:

csg_op - apply CSG operation on polygons
csg_polygon_recombination - recombine and tessellate polygons
csg_polygon_tesselation - recombine and tessellate polygons

% Geometry object primitives:

gobj_block - create block
gobj_circle - create circle
gobj_cylinder - create cylinder
gobj_ellipse - create ellipse
gobj_polygon - create polygon
gobj_rectangle - create rectangle
gobj_sphere - create sphere

% Geometry utility and help functions:

convert_gobj_polygons - extract polygons from geometry object
deduplicate - remove duplicate rows or columns within tolerance
uunique - unsorted set unique

Support

This library has been open sourced on an as is basis under the AGPLv3 License (see included LICENSE file) without warranty or support.

For technical support, consulting, and custom development of this library, commercial licensing, or use of the newer OpenCASCADE based geometry library (allowing BREP CAD geometry modeling such as STEP and IGES formats) please contact Precise Simulation directly.

License

Copyright (C) 2013-2022 Precise Simulation Ltd.

Keywords: Geometry, CSG, Mesh, MATLAB®, Octave

This program is free software; you can redistribute it and/or modify it under the terms of version 3 of the GNU Affero General Public License (AGPLv3) as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see http://www.gnu.org/licenses.

Trademarks

FEATool Multiphysics™ is a trademark of Precise Simulation Limited. MATLAB® is a registered trademark of The MathWorks, Inc. All other trademarks are the property of their respective owners. Precise Simulation and its products are not affiliated with, endorsed, or sponsored by these trademark owners.