Programming and Graphics

7.8 Three-dimensional interactive object drawing 249

mensions. The object itself is defined by a collection of independently generated
triangular elements, each defined by three nodes.

Functiondrawobj3dis identical to functiondrawplot3d, except that
the drawing module reads:

/*----------------

Draw nc elements

----------------*/

int Ibcface = 1;

int Iclock = 0;

backface(Ibcface);

backfacedir(Iclock);

const int npoints = 4;

float points[npoints-1][3];

for(int j=1;j<=nc;j++)

{

points[0][0] = xd[j][1];

points[0][1] = yd[j][1];

points[0][2] = zd[j][1];

points[1][0] = xd[j][2];

points[1][1] = yd[j][2];

points[1][2] = zd[j][2];

points[2][0] = xd[j][3];

points[2][1] = yd[j][3];

points[2][2] = zd[j][3];

points[3][0] = xd[j][1];

points[3][1] = yd[j][1];

points[3][2] = zd[j][1];

color (CYAN); // paint the elements

bool fill = true;

polyfill (fill);

poly (npoints,points);

color (lnc); // draw the element contours

fill = false;

polyfill (fill);

poly (npoints,points);

}

Function obj3dtrans is a straightforward modification of function
obj3dtransdesigned to handle element instead of line data.