Check only the current position3d of particles and segment

class Checker_T1 implements Checker{
 final IntersectionFinder _intf = new IntersectionFinderXY();

 /// Returns whether two particles A ([psA] + [iA]) and B [psB] + [iB]) intersect
 /// [psA.collide[iA]] and [psB.collide[iB]] are set to true if collision.
 /// Doesn't check if provided particles are the same or part of same group,... should be done before calling.
 /// take care of radius of each particle
 collideParticleParticle(Particles psA, int iA, Particles psB, int iB, Vector4 acol) {
   //psA = psA as Particles;
   var b = _intf.sphere_sphere(psA.position3d[iA], psA.radius[iA], psB.position3d[iB], psA.radius[iB]);
   if (b) {
     psA.collide[iA] = -1;
     psB.collide[iB] = -1;
   }
   return b;
 }

 /// Returns whether the provided particle A and the segment [s]
 /// Doesn't check if provided particles are the same or part of same group,... should be done before calling.
 /// only check against last position of the segment
 collideParticleSegment(Particles psA, int iA, Segment s, Vector4 scol) {
   var b = false;
   b = b || _intf.segment_sphere(s.ps.position3d[s.i1], s.ps.position3d[s.i2], psA.position3d[iA], psA.radius[iA]);

   if (b) {
     psA.collide[iA] = -1;
     s.collide = -1;
   }
   return b;
 }
}