/// <summary>
///
/// </summary>
/// <param name="at">Looking direction, must be a normalized vector</param>
/// <param name="upDirection">Up direction, must be a normalized vector</param>
public void LookDirection(Vector3f at, Vector3f upDirection)
{
// The two parameters cannot be parallel
Vector3f left = upDirection.Cross(ref at);
if (left == Vector3f.Zero)
{
// Prevent left from being zero
at.X += 0.01f;
at.Normalize();
left = upDirection.Cross(ref at);
}
left.Normalize();
xAxis = at;
yAxis = left;
zAxis = at.Cross(ref left);
}
protected void Orthonormalize()
{
// Make sure the axis are orthagonal and normalized
xAxis.Normalize();
yAxis -= xAxis * (xAxis * yAxis);
yAxis.Normalize();
zAxis = xAxis.Cross(ref yAxis);
}
public void FromWorld(Vector3f position, Vector3f forward, Vector3f up)
{
// Normalize forward vector
forward.Normalize();
// Calculate right vector
Vector3f right = forward.Cross(ref up);
right.Normalize();
// Recalculate up vector
up = right.Cross(ref forward);
up.Normalize();
R0 = new Vector4f(right.X, right.Y, right.Z, 0.0f);
R1 = new Vector4f(up.X, up.Y, up.Z, 0.0f);
R2 = new Vector4f(-forward.X, -forward.Y, -forward.Z, 0.0f);
R3 = new Vector4f(position.X, position.Y, position.Z, 1.0f);
}