public override bool rayCast( out RayCastOutput output, ref RayCastInput input, ref Transform transform, int childIndex )
{
// Collision Detection in Interactive 3D Environments by Gino van den Bergen
// From Section 3.1.2
// x = s + a * r
// norm(x) = radius
output = new RayCastOutput();
var pos = transform.p + MathUtils.mul( transform.q, this.position );
var s = input.Point1 - pos;
var b = Vector2.Dot( s, s ) - _2radius;
// Solve quadratic equation.
var r = input.Point2 - input.Point1;
var c = Vector2.Dot( s, r );
var rr = Vector2.Dot( r, r );
var sigma = c * c - rr * b;
// Check for negative discriminant and short segment.
if( sigma < 0.0f || rr < Settings.epsilon )
return false;
// Find the point of intersection of the line with the circle.
float a = -( c + (float)Math.Sqrt( sigma ) );
// Is the intersection point on the segment?
if( 0.0f <= a && a <= input.MaxFraction * rr )
{
a /= rr;
output.Fraction = a;
//TODO: Check results here
output.Normal = s + a * r;
output.Normal.Normalize();
return true;
}
return false;
}
