Simple Method - Slope Under Player

slope_under_simple.cs

private float groundSlopeAngle = 0f;  // angle
private Vector3 groundSlopeDir;

//  The controller hits a collider while performing a Move.
void OnControllerColliderHit (ControllerColliderHit hit)
{
    Vector3 temp = Vector3.Cross(hit.normal, Vector3.down);
    groundSlopeDir = Vector3.Cross(temp, hit.normal);
    groundSlopeAngle = Vector3.Angle(hit.normal, Vector3.up);
}