//test if circle collides with other circle
//used in robot collision detection
public bool collide(Circle2D other)
{
double dx = other.p.x - p.x;
double dy = other.p.y - p.y;
dx *= dx;
dy *= dy;
double rad_sum = other.radius + radius;
rad_sum *= rad_sum;
if ((dx + dy) < rad_sum)
return true;
return false;
}
//calculate the nearest intersection of this line
//with a circle -- if the line is interpreted as a ray
//going from its first endpoint to the second
public double nearest_intersection(Circle2D C, out bool found)
{
double dx, dy;
dx = p2.x - p1.x;
dy = p2.y - p1.y;
double px = p1.x - C.p.x;
double py = p1.y - C.p.y;
double a = dx * dx + dy * dy;
double b = 2 * px * dx + 2 * py * dy;
double c = px * px + py * py - C.radius * C.radius;
double det = b * b - 4.0 * a * c;
if (det < 0.0)
{
found = false;
return -1.0;
}
double sqrt_det = Math.Sqrt(det);
double t1 = (-b + sqrt_det) / (2 * a);
double t2 = (-b - sqrt_det) / (2 * a);
found = false;
double t = 0.0;
if (t2 < 0)
{
if (t1 > 0)
{
found = true;
t = t1;
}
}
else
{
found = true;
t = t2;
}
if (!found)
return -1.0;
return t * Math.Sqrt(dx * dx + dy * dy);
}
public Circle2D(Circle2D other)
{
p = other.p;
radius = other.radius;
}
