float newx = m.a*p.x + m.b*p.y + m.c*p.z + m.d;
float newy = m.e*p.x + m.f*p.y + m.g*p.z + m.h;
float newz = m.i*p.x + m.j*p.y + m.k*p.z + m.l;
this.p = new Point(newx, newy, newz);
// FIXME: what if we move onto exactly where another point is?
float newx = m.a*p.x + m.b*p.y + m.c*p.z + m.d;
float newy = m.e*p.x + m.f*p.y + m.g*p.z + m.h;
float newz = m.i*p.x + m.j*p.y + m.k*p.z + m.l;
this.p = new Point(newx, newy, newz);
// FIXME: what if we move onto exactly where another point is?