// general purpose facet-drop which calls xy_normal_length(), normal_length(),
// and center_height() on the subclass
bool MillingCutter::facetDrop(CLPoint &cl, const Triangle &t) const { // Drop cutter at (cl.x, cl.y) against facet of Triangle t
Point normal = t.upNormal(); // facet surface normal
if ( isZero_tol( normal.z ) ) // vertical surface
return false; //can't drop against vertical surface
assert( isPositive( normal.z ) );
if ( ( isZero_tol(normal.x) ) && ( isZero_tol(normal.y) ) ) { // horizontal plane special case
CCPoint cc_tmp( cl.x, cl.y, t.p[0].z, FACET);
return cl.liftZ_if_inFacet(cc_tmp.z, cc_tmp, t);
} else { // general case
// plane containing facet: a*x + b*y + c*z + d = 0, so
// d = -a*x - b*y - c*z, where (a,b,c) = surface normal
double d = - normal.dot(t.p[0]);
normal.normalize(); // make length of normal == 1.0
Point xyNormal( normal.x, normal.y, 0.0);
xyNormal.xyNormalize();
// define the radiusvector which points from the cc-point to the cutter-center
Point radiusvector = this->xy_normal_length*xyNormal + this->normal_length*normal;
CCPoint cc_tmp = cl - radiusvector; // NOTE xy-coords right, z-coord is not.
cc_tmp.z = (1.0/normal.z)*(-d-normal.x*cc_tmp.x-normal.y*cc_tmp.y); // cc-point lies in the plane.
cc_tmp.type = FACET;
double tip_z = cc_tmp.z + radiusvector.z - this->center_height;
return cl.liftZ_if_inFacet(tip_z, cc_tmp, t);
}
}
bool CGraphicView::GetXYPointForDXFTextExport( const CPoint& screenPt, CPoint3D& worldPt )
{
//get a ray that goes through screenPt from the front of the view frustum to the back of it
CPoint3D nearPt, farPt;
if( !Get3DPointFromScreen( screenPt, nearPt, 0.f ) )
return false;
if( !Get3DPointFromScreen( screenPt, farPt, 1.f ) )
return false;
CLine3D ray( nearPt, farPt );
//now find out where in 3D space the ray passes through the z=0 plane
CVector3D xyNormal( 0., 0., 1. );
CPoint3D ptOnXYPlane( 0., 0., 0. );
CPlane3D xyPlane( xyNormal, ptOnXYPlane );
double denom = xyNormal.dot( CVector3D( farPt, nearPt ) );
if( zero( denom ) ) return false;
double num = xyNormal.dot( CVector3D( ptOnXYPlane, nearPt ) );
double s = num/denom;
worldPt = ray.offset( s );
if( true/*is world point valid*/ )
return true;
else return false;
}