Extracting the Boundaries of Triang3d-Instances

 

       

GRAPE(triang3d, "select-boundary-disp")()

GRAPE(triang3d, "select-boundary")(value)

TRIANG3D *triang3d ;
int value;

Only those boundary-surfaces of a 3d-object are displayed, whose boundary value equals the parameter value. In the disp method the value can be set with a ruler.

   

GRAPE(triang3d, "boundary-ident-send")()

TRIANG3D *triang3d ;

One singular surface of a 3d-object can be chosen when clicking it with the left mouse button. The edges of the object separate the various surfaces. The minimal angle only just specifying an edge can be set by the root-method "choice-edge-angle-send". After clicking the middle mouse button the whole object is displayed instead of the singular surface. When clicking the right mouse button the method will be finished, the choice of the surface will be saved and a layer added:

The chosen surface becomes the negative value which is entered in the input. The Button another selection by picking starts the method again.

       

(TRIANG2D *)GRAPE(triang3d, "generate-boundary")()

(SCENE *)GRAPE(s,"generate-boundary-send")()

TRIANG3D *triang3d;
SCENE *s; /*of which the object is 3d)*/

The boundary of a 3d-object will constitute a 2d-triangulation, which in the scene method will be put into the scene tree. In most cases the following problem will arise: the triangle-normals will also be interpolated at the edges, which therefore appear blurred. The interpolation of the normals at the edges can be avoided using the triang2d-methods "show-edges-send" or "split-surfaces-send" (see 6.3.1.4).