ON_BOOL32 MyUserData::Transform( const ON_Xform& xform )
{
// Optional: call the ON_UserData::Transform() if you want the
// ON_UserData::m_userdata_xform value to be updated.
ON_UserData::Transform(xform);
// Transform any geometry you have in your class.
ON_BOOL32 rc = m_my_line.Transform(xform);
return rc;
}
int ON_Intersect(
const ON_Line& line,
const ON_Circle& circle,
double* line_t0,
ON_3dPoint& circle_point0,
double* line_t1,
ON_3dPoint& circle_point1
)
{
// transform to coordinate system where equation of circle
// is x^2 + y^2 = R^2 and solve for line parameter(s).
ON_Xform xform;
xform.ChangeBasis( circle.plane, ON_xy_plane );
xform.ChangeBasis( ON_xy_plane, circle.plane );
ON_Line L = line;
L.Transform(xform);
double r = fabs(circle.radius);
double tol = r*ON_SQRT_EPSILON;
if ( tol < ON_ZERO_TOLERANCE )
tol = ON_ZERO_TOLERANCE;
int xcnt;
if ( fabs(L.from.x - L.to.x) <= tol
&& fabs(L.from.y - L.to.y) <= tol
&& fabs(L.from.z - L.to.z) > tol )
{
xcnt = 0;
}
else
{
xcnt = Intersect2dLineCircle( L.from, L.to, r, tol, line_t0, line_t1 );
if ( xcnt == 3 )
xcnt = 1;
}
if ( xcnt == 0 )
{
if ( L.ClosestPointTo( circle.Center(), line_t0 ) )
{
xcnt = 1;
*line_t1 = *line_t0;
}
}
ON_3dPoint line_point1, line_point0 = line.PointAt(*line_t0);
circle_point0 = circle.ClosestPointTo(line_point0);
double d1, d0 = line_point0.DistanceTo(circle_point0);
if ( xcnt == 2 )
{
line_point1 = line.PointAt(*line_t1);
circle_point1 = circle.ClosestPointTo(line_point1);
d1 = line_point1.DistanceTo(circle_point1);
}
else
{
line_point1 = line_point0;
circle_point1 = circle_point0;
d1 = d0;
}
if ( xcnt==2 && (d0 > tol && d1 > tol) )
{
xcnt = 1;
if ( d0 <= d1 )
{
*line_t1 = *line_t0;
line_point1 = line_point0;
circle_point1 = circle_point0;
d1 = d0;
}
else
{
*line_t0 = *line_t1;
line_point0 = line_point1;
circle_point0 = circle_point1;
d0 = d1;
}
}
if ( xcnt == 1 && d0 > tol )
{
// TODO: iterate to closest point
}
return xcnt;
}
int ON_Intersect( // returns 0 = no intersections,
// 1 = one intersection,
// 2 = 2 intersections
// 3 = line lies on cylinder
// If 0 is returned, first point is point
// on line closest to cylinder and 2nd point is the point
// on the sphere closest to the line.
// If 1 is returned, first point is obtained by evaluating
// the line and the second point is obtained by evaluating
// the cylinder.
const ON_Line& line,
const ON_Cylinder& cylinder, // if cylinder.height[0]==cylinder.height[1],
// then infinite cyl is used. Otherwise
// finite cyl is used.
ON_3dPoint& A, ON_3dPoint& B // intersection point(s) returned here
)
{
ON_BOOL32 bFiniteCyl = true;
int rc = 0;
const double cylinder_radius = fabs(cylinder.circle.radius);
double tol = cylinder_radius*ON_SQRT_EPSILON;
if ( tol < ON_ZERO_TOLERANCE )
tol = ON_ZERO_TOLERANCE;
ON_Line axis;
axis.from = cylinder.circle.plane.origin + cylinder.height[0]*cylinder.circle.plane.zaxis;
axis.to = cylinder.circle.plane.origin + cylinder.height[1]*cylinder.circle.plane.zaxis;
if ( axis.Length() <= tol ) {
axis.to = cylinder.circle.plane.origin + cylinder.circle.plane.zaxis;
bFiniteCyl = false;
}
//ON_BOOL32 bIsParallel = false;
double line_t, axis_t;
if ( !ON_Intersect(line,axis,&line_t,&axis_t) ) {
axis.ClosestPointTo( cylinder.circle.plane.origin, &axis_t );
line.ClosestPointTo( cylinder.circle.plane.origin, &line_t );
}
ON_3dPoint line_point = line.PointAt(line_t);
ON_3dPoint axis_point = axis.PointAt(axis_t);
double d = line_point.DistanceTo(axis_point);
if ( bFiniteCyl ) {
if ( axis_t < 0.0 )
axis_t = 0.0;
else if ( axis_t > 1.0 )
axis_t = 1.0;
axis_point = axis.PointAt(axis_t);
}
if ( d >= cylinder_radius-tol) {
rc = ( d <= cylinder_radius+tol ) ? 1 : 0;
A = line_point;
ON_3dVector V = line_point - axis_point;
if ( bFiniteCyl ) {
V = V - (V*cylinder.circle.plane.zaxis)*cylinder.circle.plane.zaxis;
}
V.Unitize();
B = axis_point + cylinder_radius*V;
if ( rc == 1 ) {
// check for overlap
ON_3dPoint P = axis.ClosestPointTo(line.from);
d = P.DistanceTo(line.from);
if ( fabs(d-cylinder_radius) <= tol ) {
P = axis.ClosestPointTo(line.to);
d = P.DistanceTo(line.to);
if ( fabs(d-cylinder_radius) <= tol ) {
rc = 3;
A = cylinder.ClosestPointTo(line.from);
B = cylinder.ClosestPointTo(line.to);
}
}
}
}
else {
// transform to coordinate system where equation of cyl
// is x^2 + y^2 = R^2 and solve for line parameter(s).
ON_Xform xform;
xform.Rotation( cylinder.circle.plane, ON_xy_plane );
ON_Line L = line;
L.Transform(xform);
const double x0 = L.from.x;
const double x1 = L.to.x;
const double x1mx0 = x1-x0;
double ax = x1mx0*x1mx0;
double bx = 2.0*x1mx0*x0;
double cx = x0*x0;
const double y0 = L.from.y;
const double y1 = L.to.y;
const double y1my0 = y1-y0;
double ay = y1my0*y1my0;
double by = 2.0*y1my0*y0;
double cy = y0*y0;
double t0, t1;
int qerc = ON_SolveQuadraticEquation(ax+ay, bx+by, cx+cy-cylinder_radius*cylinder_radius,
&t0,&t1);
if ( qerc == 2 ) {
// complex roots - ignore (tiny) imaginary part caused by computational noise.
t1 = t0;
}
A = cylinder.ClosestPointTo(line.PointAt(t0));
B = cylinder.ClosestPointTo(line.PointAt(t1));
d = A.DistanceTo(B);
if ( d <= ON_ZERO_TOLERANCE ) {
A = line_point;
ON_3dVector V = line_point - axis_point;
if ( bFiniteCyl ) {
V = V - (V*cylinder.circle.plane.zaxis)*cylinder.circle.plane.zaxis;
}
V.Unitize();
B = axis_point + cylinder_radius*V;
rc = 1;
}
else
rc = 2;
}
return rc;
}
