<h1>Custom size map</h1>
-\image html blsurf_parameters_sizemap.png
+\image html blsurf_parameters_sizemap1.png
User sizes can be defined on faces, edges or vertices.
<ul>
</ul></li>
</ul>
-<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
-
\anchor blsurf_sizemap_computation
<h2>Computation of the physical size</h2>
\n
</ul>
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".
+\anchor blsurf_attractor
+<h2>Advanced maps</h2>
+\n
+\image html blsurf_parameters_sizemap2.png
+\n
+More specific size maps can be defined on faces.
+
+<ul>
+<li> <i> Attractors </i> allow to define the size of the mesh elements on a face so that the mesh is the finest on the attractor shape and becomes coarser when getting far from this shape.
+<ul>
+<li> The selected attractor can be a Vertex, an Edge, a Wire or a Compound mixing several entities of those types.</li>
+<li> The attractor doesn't have to be a sub-shape of the shape to mesh.</li>
+<li> The size will grow exponentially (see formula below) but is bounded by gradation, \n so if you want the formula to be strictly respected, you should set the <i>gradation</i>
+to its maximum (2.5) in the <i>arguments</i> tab.
+</ul>
+\n
+<li> Furthermore you can choose to <i> keep the size constant </i> until a certain distance from a shape. This option can be combined or not with an <i>attractor</i> size map described above.
+<ul>
+<li> If the two options are combined the size will remain constant until the distant specified in "constant over" and grow then as prescribed by the attractor function.</li>
+<li> Else the growing is only controled by the standard arguments of BLSURF (gradation ...).</li>
+</ul>
+</ul>
+
+\image html blsurf_attractors2.png "Example of mesh created using attractors, the attractors here are the side edges and the size grow from the side of the surface towards the apex"
+\n
+\image html blsurf_const_size_near_shape2.png "Example of size map with constant size option, the size is kept constant on the left side of the surface until a certain distance"
+\n
+Remark : The validation of the hypothesis might take a few seconds if attractors are defined or the "constant size" option is used because a map of distances has to be built on the whole surface for each face where such an hypothesis has been defined.
+
+<br><b>See Also</b> a sample TUI Script of the \ref tui_blsurf "creation of a BLSurf hypothesis", including size map.
+
+\anchor blsurf_attractor_computation
+<h2>Computation of attractors</h2>
+\n
+The size grow exponentially following the equation : h(d) = User size + (h_start - User Size) * exp( -(d / R)^2 ).
+\n
+Where :
+<ul>
+<li>h_start is the desired size on the given attractor shape</li>
+<li>d is the distance of the current point from the attractor shape. The distance is the geodesic distance (i.e. calculated by following the surface to be meshed) </li>
+<li>R is called the distance of influence and allows controlling the growth rate of the mesh </li>
+</ul>
<h1>Custom enforced vertices</h1>
Currently BLSURF plugin has the following limitations.
<ul>
- <li>The created mesh will contain inverted elements if it is based on a shape,
- consisting of more than one face (box, cone, torus...) and if
- the option "Allow Quadrangles (Test)" has been checked before
- computation.</li>
-
- <li>SIGFPE exception is raised at the attempt to compute the mesh
- based on a box when the option "Patch independent" is checked.</li>
-
<li>BLSURF algorithm cannot be used as a local algorithm (on
sub-meshes) or as a provider of a low-level
mesh for some 3D algorithms, because the BLSURF mesher (and
<li> BLSURF + Projection 2D from faces meshed by BLSURF;</li>
<li> local BLSURF + Extrusion 3D;</li>
</ul>
- </li>
+ </li>
</ul>
*/
