For each polygon in a given POLYGONS structure, this command contracts the polygon by replacing it by a new polygon, which is similar to the original and its center and orientation are the same as the original.  The ratio of similarity is specified with the parameter r.

This command produces a POLYGONS object, which can be used in a PLOT3D data structure, or displayed using the plots:-display command.

The cutin command forces a display style of PATCHNOGRID. Other options to style are ignored.

$\mathrm{with}\left(\mathrm{plottools}\right)\:$

$\mathrm{with}\left(\mathrm{plots}\right)\:$

$\mathrm{display}\left(\mathrm{cutin}\left(\mathrm{dodecahedron}\left(\right)\,\frac{2}{3}\right)\,\mathrm{shading}=\mathrm{zhue}\right)$

$p≔\mathrm{convert}\left(\mathrm{plot3d}\left(\sin \left(xy\right)\,x=-1..1\,y=-1..1\,\mathrm{grid}=\left[15\,15\right]\right)\,\mathrm{POLYGONS}\right)\:$

$\mathrm{display}\left(\mathrm{cutin}\left(p\,\frac{2}{3}\right)\,\mathrm{axes}=\mathrm{frame}\,\mathrm{lightmodel}=\mathrm{light1}\,\mathrm{orientation}=\left[150\,85\right]\right)$