Editing Geometry package
Jump to navigation
Jump to search
The edit can be undone. Please check the comparison below to verify that this is what you want to do, and then publish the changes below to finish undoing the edit.
Latest revision | Your text | ||
Line 32: | Line 32: | ||
</syntaxhighlight>}} | </syntaxhighlight>}} | ||
As you can see the polygon has lots of points. We need to simplify the polygon in order to obtain a mesh of reasonable size. Otherwise gmsh will have problems meshing and the result could be huge (or a segmentation fault :( ). The package geometry (> 1.5.0) comes with a simplification function that uses the [http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm Ramer-Douglas-Peucker algorithm] to reduce thenumber of points in the polygon. | As you can see the polygon has lots of points. We need to simplify the polygon in order to obtain a mesh of reasonable size. Otherwise gmsh will have problems meshing and the result could be huge (or a segmentation fault :( ). The package geometry (> 1.5.0) comes with a simplification function that uses the [http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm Ramer-Douglas-Peucker algorithm] to reduce thenumber of points in the polygon. | ||
{{Code|Symplification of a polygon compatible with geometry package|<syntaxhighlight lang=" | {{Code|Symplification of a polygon compatible with geometry package|<syntaxhighlight lang="matlab" style="font-size:13px"> | ||
P = simplifypolygon(P, 'tol', 1e-3); | P = simplifypolygon(P, 'tol', 1e-3); | ||
</syntaxhighlight>}} | </syntaxhighlight>}} | ||
Line 39: | Line 39: | ||
The next step is to mesh the interior of the polygon. To do this we could just call {{Codeline|delaunay}} on the polygon and be done with it, but in general such mesh wont be so nice (you will need to add interior points). A very effective way of generating a good mesh is to use the package {{Forge|msh}}, which requires [http://geuz.org/gmsh/ Gmsh] installed in your system. The function {{Codeline|data2geo}} in the Geometry package makes our work very easy: | The next step is to mesh the interior of the polygon. To do this we could just call {{Codeline|delaunay}} on the polygon and be done with it, but in general such mesh wont be so nice (you will need to add interior points). A very effective way of generating a good mesh is to use the package {{Forge|msh}}, which requires [http://geuz.org/gmsh/ Gmsh] installed in your system. The function {{Codeline|data2geo}} in the Geometry package makes our work very easy: | ||
{{Code|Generating mesh for plot with msh package|<syntaxhighlight lang=" | {{Code|Generating mesh for plot with msh package|<syntaxhighlight lang="matlab" style="font-size:13px"> | ||
pkg load msh | pkg load msh | ||
filename = tmpnam (); | filename = tmpnam (); | ||
Line 50: | Line 50: | ||
After this code finishes, the structure T contains our mesh. To plot the generated mesh we use the function {{Codeline|pdemesh}} from the {{Forge|fpl}} package. In general is a good idea to use the openGL render (called ''fltk'') to plot meshes. | After this code finishes, the structure T contains our mesh. To plot the generated mesh we use the function {{Codeline|pdemesh}} from the {{Forge|fpl}} package. In general is a good idea to use the openGL render (called ''fltk'') to plot meshes. | ||
{{Code|Plotting mesh with fpl package|<syntaxhighlight lang=" | {{Code|Plotting mesh with fpl package|<syntaxhighlight lang="matlab" style="font-size:13px"> | ||
pkg load fpl | pkg load fpl | ||
graphics_toolkit ('fltk') | graphics_toolkit ('fltk') |