//--------------------------------------------------------------------------------
void Cone3f::SampleNormal( Vector3f& normal, float theta, float height ) const
{
// Define the axis of the cylinder, and find its length.
Vector3f v = P1 - P2;
Vector3f vnorm = Vector3f::Normalize( v );
float l = v.Magnitude();
Vector3f up = Vector3f( 0.0f, 1.0f, 0.0f );
// Find the unit vector perpendicular to the axis, that is pointing closest to the (0,1,0) direction.
// If the axis points in the (0,1,0) direction, then use (1,0,0) as the unit vector.
Vector3f unit;
if ( vnorm == up || vnorm == -up ) {
unit = Vector3f( 1.0f, 0.0f, 0.0f );
} else {
Vector3f temp = Vector3f::Cross( vnorm, up );
unit = Vector3f::Cross( temp, vnorm );
unit.Normalize();
}
float slope = ( R2 - R1 ) / l;
float radius = R2 + slope * height * l;
// Calculate the position, which is a combination of an offset to the p2 endpoint,
// shifted along the axis of the cylinder, and a rotated and scaled radius component.
Matrix3f r;
r.RotationEuler( vnorm, theta );
// Calculate the normal vector, which is dependent on the delta in radii at each
// end of the cylinder.
normal = r * unit * radius + vnorm * slope * radius;
normal.Normalize();
}
const Vector3f GravitationalForce::CalculateForce( const Body &a, const Body &b ) const {
const Vector3f vDiff = b.Position - a.Position;
const float numerator = Constant * ( a.Mass * b.Mass );
const float denominator = std::pow( vDiff.Magnitude(), 2 );
return vDiff.Normalised() * ( numerator / denominator );
}
void Camera::LookAt(const Vector3f &point, Vector3f up)
{
m_look=m_position-point;
if(up.Magnitude()!=0.0f)
{
m_up=up;
}
m_right=m_up.Cross(m_look);
}
bool Intersect::BoundsSphere (const Bounds& bounds, const Vector3f& pos, float radius)
{
const Vector3f& center = bounds.GetCenter();
Vector3f dir (center - pos);
float mag = dir.Magnitude();
if (mag > radius)
{
dir /= mag;
dir *= radius;
return bounds.Contains(pos + dir);
}
return true;
}
void Arcball::Drag(const Point3f* _point, Quaternion* qNewRotation)
{
MapToSphere(_point, &endVector);
if(qNewRotation)
{
Vector3f vPerpendicular;
//compute the vector perpendicular to the begin and end vectors
vPerpendicular = Vector3f::Cross(&startVector, &endVector);
//compute the length of the perpendicular vecotr
if(vPerpendicular.Magnitude() > 0)
{
//return the perpendicular vector as the transform
*qNewRotation = Quaternion(vPerpendicular.X(), vPerpendicular.Y(), vPerpendicular.Z(), Vector3f::Dot(&startVector, &endVector));
}
else
{
//the begin and end vectors coincide, so return an identity transform
*qNewRotation = Quaternion(0, 0, 0, 0);
}
}
}
