// used for the segment intersection with radius code,
// if there is not a collision, find the nearest endpoint via point-line distance
// then don't forget that we move back the parameter t by enough to add a buffer from the collision
private double NonIntersectingSegmentDistance(myLineSegment o, double t, double radius)
{
double mindist2 = double.MaxValue;
mindist2 = Math.Min(mindist2, o.DistToPoint2(p1));
mindist2 = Math.Min(mindist2, o.DistToPoint2(p2));
mindist2 = Math.Min(mindist2, DistToPoint2(o.p1));
mindist2 = Math.Min(mindist2, DistToPoint2(o.p2));
if (mindist2 < radius * radius)
{
// there is a collision without intersection, move up as far as we can without collision
// note: we use the t term that we passed in, and subtract enough so that the perpendicular distance equals radius
// also note: if t == 0 that means that the collision is already happening without a move... we're stuck?
//if (t < 1e-6)
// return 0.0;
// Scoot t back so the radius is equal to our radius
double sintheta = Math.Abs(o.v.cross(v)) / (v.mag() * o.v.mag());
t -= (radius / sintheta) / v.mag();
// also remove the collision buffer, then return it
t -= (CollisionBuffer / v.mag());
return(t < 0.0 ? 0.0 : t);
}
// if there is still no collision, just return the full 1.0 parameter value
return(1.0);
}
public double SegmentIntersectionWithRadius(myLineSegment o, double radius)
{
// get determinate and check for parallel lines
double D = v.cross(o.v);
if (Math.Abs(D) < 1e-6)
{
// Are we already within the line radius?
if (o.DistToPoint2(p1) < radius * radius)
{
return(0.0);
}
// Check if we are now moving onto the line segement.
else if (NonIntersectingSegmentDistance(o, 0.0, radius) < 0.1)
{
// return 1.0;
return(Math.Min(Geometry.MovingCirlcePointCast(this, radius, o.p1), Geometry.MovingCirlcePointCast(this, radius, o.p2)));
}
// No collision
else
{
return(1.0);
}
}
// relative vector from the other segments starting point to my own
myVector relVect = new myVector(p1, o.p1);
double t = relVect.cross(o.v) / D;
double u = relVect.cross(v) / D;
// find if the intersection happens along the other line segment
if (u < 0.0 || u > 1.0)
{
return(NonIntersectingSegmentDistance(o, t, radius));
}
// find if the intersection happens along this line segment
if (t < 0.0 || t > 1.0)
{
return(NonIntersectingSegmentDistance(o, t, radius));
}
// An intersection is happening! Scoot the t parameter back a bit for the radius and buffer then return it
// Scoot t back so the radius is equal to our radius
double sintheta = Math.Abs(o.v.cross(v)) / (v.mag() * o.v.mag());
t -= (radius / sintheta) / v.mag();
// also remove the collision buffer, then return it
t -= (CollisionBuffer / v.mag());
return(t < 0.0 ? 0.0 : t);
}
