10.2.7 ClipFacet

• ClipFacet( <facet list>, <plane> )
• Description: a facet is represented under the form of a 3D points list ended by the constant jump. Those points should be coplanar. Example: [ Origin, M(0,1,0), M(0,0,3), jump] is a facet. The facets are oriented by the vertices order of appearance.

That function cuts all the facets in the list with the <plane>. That plane is represented under the form of a list [A,u] where A is a 3Dpoint and u a 3Dvector, ie: the plane passing through A normal to the vector u. Only the part of the facets in the half plane containing u is kept. The function returns the list of the cut facets.

• Exemple(s): the command [P:=Tetra(Origin, vecI, vecJ, vecK), ClipFacet(P, [M(0,0,0.5), -vecK])] defines a tetrahedron called P and returns the part of P located below the plane (under the form of facets).

 \begin{texgraph}[name=ClipFacet, export=pgf]    view(-1,1,-1,1), view3D(-2,2,-2,2,-2,2),    Marges(0,0,0,0), size(7.5),    P:=Tetra(Origin, vecI, vecJ, vecK),    P’:=ClipFacet(P, [M(0,0,0.5), -vecK]),    DrawFacet( P’, [color:=pink])   \end{texgraph}

ClipFacet