private void getRotateAroundCamera(Point endPoint)
{
float adjustPos = (float)Math.Tan(ExtensionGL.Radians(FOV / 2.0f)) * 0.1f / (panelOpenGL.Height / 2.0f);
float dx = (endPoint.X - startPoint.X);
float dy = (endPoint.Y - startPoint.Y);
float dxmin = panelOpenGL.Width / 100f;
float dymin = panelOpenGL.Height / 100f;
float x = (Math.Abs(dx) >= dxmin) ? dx * adjustPos : 0;
float y = (Math.Abs(dy) >= dymin) ? dy * adjustPos : 0;
Vector3 perp = new Vector3(-y, -x, 0f);
float theta = (float)Math.Atan(perp.Length / 0.1f);
//Compute the length of the perpendicular vector
if (perp.Length > float.Epsilon) //if its non-zero
{
// Return the perpendicular vector as the transform after all
rotation.X = perp.X;
rotation.Y = perp.Y;
rotation.Z = perp.Z;
//In the quaternion values, w is cosine (theta / 2), where theta is the rotation angle
rotation.W = (float)Math.Cos(theta / 2);
var trans = new Transform3DGroup();
trans.TranslateBy(-camera.Position);
trans.RotateBy(rotation);
trans.TranslateBy(camera.Position);
currentTrans = trans;
updateModelMatricies();
}
}