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275 lines
11 KiB
Plaintext
275 lines
11 KiB
Plaintext
/*!
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\page blsurf_hypo_page BLSURF Parameters hypothesis
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\n BLSURF Parameters hypothesis works only with <b>BLSURF</b> 2d
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algorithm. This algorithm is a commercial software.
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<h1>General parameters</h1>
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\image html blsurf_parameters.png
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<ul>
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<li><b>Name</b> - allows defining the name of the hypothesis (BLSURF
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Parameters_n by default).</li>
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<li><b>Physical Mesh</b> - can be set to None, Custom or Size Map
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<ul>
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<li>if set to "Custom", allows user input in the
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in <b>User size</b>, <b>Max Physical Size</b> and <b>Min Physical
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Size</b> fields.</li>
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<li>if set to "Size Map", behaves like "Custom" mode and takes into account the custom elements sizes given in the Size Map tab.</li>
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</ul>
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</li>
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<li><b>User size</b> - defines the size of the generated mesh elements. </li>
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<li><b>Max Physical Size</b> - defines the upper limit of mesh element size. </li>
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<li><b>Min Physical Size</b> - defines the lower limit of mesh element size. </li>
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<li><b>Geometrical mesh</b> - if set to "Custom", allows user input in
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<b>Angle Mesh S</b>, <b>Angle Mesh C</b> and
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<b>Gradation</b> fields. These fields control
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computation of the element size, so called <i>geometrical size</i>, conform to
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the surface geometry considering local curvatures. \n
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If both the <b>User size</b> and the <i>geometrical size</i> are defined, the
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eventual element size correspond to the least of the two. </li>
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<li><b>Angle Mesh S</b> - maximum angle between the mesh face and the
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tangent to the geometrical surface at each mesh node, in degrees. </li>
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<li><b>Angle Mesh C</b> - maximum angle between the mesh edge and the
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tangent to the geometrical curve at each mesh node, in degrees. </li>
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<li><b>Max Geometrical Size</b> - defines the upper limit of the <i>geometrical size</i>.</li>
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<li><b>Min Geometrical Size</b> - defines the lower limit of the <i>geometrical size</i>.</li>
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<li><b>Gradation</b> - maximum ratio between the lengths of
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two adjacent edges. </li>
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<li><b>Allow Quadrangles</b> - if checked, allows the creation of quadrilateral elements.</li>
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<li><b>Patch independent</b> - if checked, geometrical
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edges are not respected and all geometrical faces are meshed as one
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hyper-face.</li>
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<h1>Advanced parameters</h1>
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\image html blsurf_parameters_advanced.png
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<li><b>Topology</b> - allows creation of a conform mesh on a shell of
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not sewed faces.
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<ul>
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<li>"From CAD" means that mesh conformity is assured by conformity
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of a shape.</li>
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<li>"Pre-process" and "Pre-process++" allow the BLSURF software to
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pre-process the geometrical model to eventually produce a conform
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mesh. </li>
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</ul>
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<li><b>Verbosity level</b> - Defines the percentage of "verbosity" of
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BLSURF [0-100].</li>
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<li><b>Add option</b> - provides the choice of multiple advanced
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options, which appear, if selected, in a table where it is possible to
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input the value of the option and to edit it later.</li>
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<li><b>Clear option</b> - removes the option selected in the table.
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</ul>
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\n
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The following options are commonly usable. The notion of <i>diag</i>
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used in the descriptions means
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the diagonal of the bounding box of the geometrical object to mesh.
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<ul>
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<li><b>topo_eps1</b> (real) - is the tolerance level inside a CAD
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patch. By default is equal to <i>diag</i> <20> 10-4. This tolerance is used to
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identify nodes to merge within one geometrical face when \b Topology
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option is to pre-process. Default is <i>diag</i>/10.0.</li>
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<li><b>topo_eps2</b> (real) - is the tolerance level between two CAD
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patches. By default is equal to <i>diag</i> <20> 10-4. This tolerance is used to
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identify nodes to merge over different geometrical faces when
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\b Topology option is to pre-process. Default is <i>diag</i>/10.0.</li>
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<li>\b LSS (real) - is an abbreviation for "length of sub-segment". It is
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a maximal allowed length of a mesh edge. Default is 0.5.</li>
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<li>\b frontal (integer)
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<ul>
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<li> 1 - the mesh generator inserts points with an advancing front method.</li>
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<li> 0 - it inserts them with an algebraic method (on internal edges). This method is
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slightly faster but generates less regular meshes. </li>
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</ul>
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Default is 0.</li>
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\anchor blsurf_hinterpol_flag
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<li>\b hinterpol_flag (integer) - determines the computation of an
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interpolated value <i>v</i> between two points <i>P1</i> and <i>P2</i> on a
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curve. Let <i>h1</i> be the value at point <i>P1,</i> <i>h2</i> be the value at point
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<i>P2,</i> and <i>t</i> be a parameter varying from 0 to 1 when moving from <i>P1
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to</i> <i>P2</i> .
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<ul>
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<li>0 - the interpolation is linear: <i>v = h1 + t (h2 - h1 )</i></li>
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<li>1 - the interpolation is geometric: <i>v = h1 * pow( h2/h1, t)</i></li>
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<li>2 - the interpolation is sinusoidal: <i>v = (h1+h2)/2 +
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(h1-h2)/2*cos(PI*t)</i></li>
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</ul>
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Default is 0.</li>
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\anchor blsurf_hmean_flag
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<li>\b hmean_flag (integer) - determines the computation of the average of several
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values:<ul>
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<li>-1 - the minimum is computed.</li>
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<li>0 or 2 - the arithmetic average computed.
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<li>1 - the geometric average is computed.</li>
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</ul>
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Default is 0.</li>
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<li>\b CheckAdjacentEdges, \b CheckCloseEdges and \b CheckWellDefined
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(integers) - gives the number of calls of equally named subroutines the
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purpose of which is to improve the mesh of domains having narrow
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parts. At each iteration,\b CheckCloseEdges decreases the sizes of the
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edges when two boundary curves are neighboring,\b CheckAdjacentEdges
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balances the sizes of adjacent edges, and \b CheckWellDefined checks if
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the parametric domain is well defined. Default values are 0.</li>
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<li>\b CoefRectangle (real)- defines the relative thickness of the rectangles
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used by subroutine \b CheckCloseEdges (see above). Default is 0.25.</li>
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<li>\b eps_collapse (real) - if more than 0.0, BLSURF removes
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curves whose lengths are less than \b eps_collapse. To obtain an
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approximate value of the length of a curve, it is arbitrarily
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split into 20 edges. Default is 0.0.</li>
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<li>\b eps_ends (real) - is used to detect the curves whose lengths are very
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small, which sometimes constitutes an error. A message is printed
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if<i> fabs(P2-P1) < eps_ends</i>, where <i>P1</i> and <i>P2</i> are the
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extremities of a curve. Default is <i>diag</i>/500.0.</li>
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<li>\b prefix (char) - is a prefix of the files generated by
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BLSURF. Default is "x".</li>
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<li>\b refs (integer) - reference of a surface, used when exporting
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files. Default is 1.</li>
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</ul>
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\n
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The following advanced options are not documented and you can use them
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at your own risk.
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\n\n Integer variables:
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<ul>
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<li> addsurf_ivertex</li>
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<li> background </li>
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<li> coiter </li>
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<li> communication </li>
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<li> decim </li>
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<li> export_flag </li>
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<li> file_h </li>
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<li> gridnu </li>
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<li> gridnv </li>
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<li> intermedfile </li>
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<li> memory </li>
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<li> normals </li>
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<li> optim </li>
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<li> pardom_flag </li>
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<li> pinch </li>
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<li> rigid </li>
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<li> surforient </li>
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<li> tconf </li>
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<li> topo_collapse </li>
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</ul>
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Real variables:
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<ul>
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<li> addsurf_angle </li>
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<li> addsurf_R </li>
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<li> addsurf_H </li>
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<li> addsurf_FG </li>
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<li> addsurf_r </li>
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<li> addsurf_PA </li>
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<li> angle_compcurv </li>
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<li> angle_ridge </li>
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<li> eps_pardom </li>
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</ul>
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String variables:
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<ul>
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<li> export_format </li>
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<li> export_option </li>
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<li> import_option </li>
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</ul>
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<h1>Custom size map</h1>
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\image html blsurf_parameters_sizemap.png
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It is possible to define user sizes on faces, edges or verteces.
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<ul>
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<li>Those faces, edges and verteces must be sub-shapes (from explode command) of the meshed geometry object.</li>
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<li>Groups of faces, edges and verteces are also handled.</li>
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<li>Multi-selection is possible.</li>
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<li>The sizes are constant values.</li>
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</ul>
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<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
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\anchor blsurf_sizemap_computation
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<h2>Computation of the physical size</h2>
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Here is the detail on the calculation of the size (from BLSurf documentation).
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\n
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The size is obtained by querying sizemap functions associated to the input CAD object for surfaces, curves and points.
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Each function can either return a value h (which is then trimmed between the two bounds hphymin and hphymax), or "no answer" (by not assigning a value to h), thus providing great flexibility in the specification of the sizes. The computation depends whether point P is internal to a surface, internal to a curve, or at the end of several curves:
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<ul>
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<li> If point P is internal to a surface, the CAD surface size function is queried. If no answer is returned, one interpolates with the values at the vertices of the discretized interface curves.</li>
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<li> If point P is internal to a curve, the CAD curve size function is queried first. If no answer is returned, the surface size function is queried for every adjacent surface and the mean value of the returned values is computed. If no answer is returned, sizes h1 and h2 at both ends of the curve are considered (see next item) and the interpolated value is computed.</li>
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<li> If point P is at the extremity of several curves, the CAD point size function is queried first. If no answer is returned, the curve size function is queried for every adjacent curve and the mean value of the returned values is computed. If no answer is returned, the surface size function is queried for every adjacent surface and the mean value of the returned values is computed. If there is still no answer returned, the default value hphydef is kept.</li>
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</ul>
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In order to compute the mean of several values, the arithmetic mean is used by default, but this can be modified by the parameter \ref blsurf_hmean_flag "hmean flag". In the same way, in order to interpolate two values, a linear interpolation is used by default, but this can be modified by \ref blsurf_hinterpol_flag "hinterpol flag".
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<h1>Custom enforced vertices</h1>
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\image html blsurf_parameters_enforced_vertices.png
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It is possible to define some enforced vertices to BLSurf algorithm without any vertex creation into the CAD.
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<ul>
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<li>Enforced vertices are the projection of a given point defines by its (x,y,z) coordinates on the concerned face.</li>
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<li>It is possible to define several enforced vertices on 1 face.</li>
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<li>Group of faces are also handled.</li>
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<li>If the projection point is on the boundary or outside the face, then it will be ignored.</li>
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</ul>
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<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including enforced vertices.
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<h1>Limitations</h1>
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Currently BLSURF plugin has the following limitations.
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<ul>
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<li>The created mesh will contain inverted elements if it is based on a shape,
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consisting of more than one face (box, cone, torus...) and if
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the option "Allow Quadrangles (Test)" has been checked before
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computation.</li>
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<li>SIGFPE exception is raised at the attempt to compute the mesh
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based on a box when the option "Patch independent" is checked.</li>
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<li>BLSURF algorithm cannot be used as a local algorithm (on
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sub-meshes) or as a provider of a low-level
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mesh for some 3D algorithms, because the BLSURF mesher (and
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consequently plugin) does not provide the information on node
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parameters on edges (U) and faces (U,V). For example the
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following combinations of algorithms are impossible:
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<ul>
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<li> global MEFISTO or Quadrangle(mapping) + local BLSURF;</li>
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<li> BLSUFR + Projection 2D from faces meshed by BLSURF;</li>
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<li> local BLSURF + Extrusion 3D;</li>
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</ul>
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</li>
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</ul>
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*/
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