public void test_convert_to_2d()
{
Triangle3d t = new Triangle3d(new xyz(0, 0, 0), new xyz(5, 0, 0), new xyz(5, 5, 0));
Triangle2d t2 = t.ConvertTo2d();
Assert.IsTrue(fp.eq_inches(new xy(0, 0), t2.a));
Assert.IsTrue(fp.eq_inches(new xy(5, 0), t2.b));
Assert.IsTrue(fp.eq_inches(new xy(5, 5), t2.c));
}
public static bool TriangleLineSegmentIntersect3d(Triangle3d t, xyz d, xyz e, out xyz pt1, out xyz pt2, int sign_d, int sign_e)
{
if (
(sign_d > 0) &&
(sign_e > 0)
)
{
pt1 = null;
pt2 = null;
return(false);
}
if (
(sign_d < 0) &&
(sign_e < 0)
)
{
pt1 = null;
pt2 = null;
return(false);
}
if (
(sign_d == 0) &&
(sign_e == 0)
)
{
// the segment is in the same plane as the triangle
// convert everything to 2d
Triangle2d t2d = t.ConvertTo2d();
xy d2 = ut.ConvertPointTo2d(d, t.a, t.iv, t.jv);
xy e2 = ut.ConvertPointTo2d(e, t.a, t.iv, t.jv);
bool bd = t2d.PointInside(d2);
bool be = t2d.PointInside(e2);
if (bd && be)
{
pt1 = d;
pt2 = e;
return(true);
}
else
{
xy w1;
xy w2;
bool bresult = t2d.SegmentIntersection(d2, e2, out w1, out w2);
if (bresult)
{
pt1 = ut.Convert2dPointTo3d(w1, t.a, t.iv, t.jv);
if (w2 != null)
{
pt2 = ut.Convert2dPointTo3d(w2, t.a, t.iv, t.jv);
}
else
{
pt2 = null;
}
}
else
{
pt1 = null;
pt2 = null;
}
return(bresult);
}
}
else
{
// the segment intersects the plane in only one point, so pt2 will be null
pt2 = null;
xyz p;
if (sign_d == 0)
{
p = d;
}
else if (sign_e == 0)
{
p = e;
}
else
{
// find the point where the pp_segment intersects the plane
double u = xyz.dotsub(t.n, t.a, d) / xyz.dotsub(t.n, e, d);
p = (e - d).multiply_in_place(u).add_in_place(d);
}
Triangle2d t2d = t.ConvertTo2d();
xy ipt = ut.ConvertPointTo2d(p, t.a, t.iv, t.jv);
bool b = t2d.PointInside(ipt);
if (b)
{
pt1 = p.copy();
}
else
{
pt1 = null;
}
return(b);
}
}