//Mouse drag, calculate rotation
public void drag(Point NewPt, Quat4f NewRot)
{
//Map the point to the sphere
this.mapToSphere(NewPt, EnVec);
//Return the quaternion equivalent to the rotation
if (NewRot != null)
{
Vector3f Perp = new Vector3f();
//Compute the vector perpendicular to the begin and end vectors
Vector3f.cross(Perp, StVec, EnVec);
//Compute the length of the perpendicular vector
if (Perp.length() > Epsilon)
//if its non-zero
{
//We're ok, so return the perpendicular vector as the transform after all
NewRot.x = Perp.x;
NewRot.y = Perp.y;
NewRot.z = Perp.z;
//In the quaternion values, w is cosine (theta / 2), where theta is the rotation angle
NewRot.w = Vector3f.dot(StVec, EnVec);
}
//if it is zero
else
{
//The begin and end vectors coincide, so return an identity transform
NewRot.x = NewRot.y = NewRot.z = NewRot.w = 0.0f;
}
}
}
private void drag(Point MousePt)
{
Quat4f ThisQuat = new Quat4f();
arcBall.drag(MousePt, ThisQuat); // Update End Vector And Get Rotation As Quaternion
lock (matrixLock)
{
if (isMiddleDrag) //zoom
{
double len = Math.Sqrt(mouseStartDrag.X * mouseStartDrag.X + mouseStartDrag.Y * mouseStartDrag.Y)
/ Math.Sqrt(MousePt.X * MousePt.X + MousePt.Y * MousePt.Y);
ThisTransformation.Scale = (float)len;
ThisTransformation.Pan = new Vector3f(0, 0, 0);
ThisTransformation.Rotation = new Quat4f();
ThisTransformation.MatrixMultiply(ThisTransformation, LastTransformation); // Accumulate Last Rotation Into This One
}
else if (isRightDrag) //pan
{
float x = (float)(MousePt.X - mouseStartDrag.X) / (float)((this.AnT.Width) * 10);
float y = (float)(MousePt.Y - mouseStartDrag.Y) / (float)((this.AnT.Height) * 10);
float z = 0.0f;
trans_x += (double)x;
trans_y += (double)y;
trans_z += (double)z;
RedrawScene(trans_x, -1 * trans_y, trans_z);
/* ThisTransformation.Pan = new Vector3f(x, -1*y, z);
* ThisTransformation.Scale = 1.0f;
* ThisTransformation.Rotation = new Quat4f();
* ThisTransformation.MatrixMultiply(ThisTransformation, LastTransformation);*/
}
else if (isLeftDrag) //rotate
{
ThisTransformation.Pan = new Vector3f(0, 0, 0);
ThisTransformation.Scale = 1.0f;
ThisTransformation.Rotation = ThisQuat;
ThisTransformation.MatrixMultiply(ThisTransformation, LastTransformation);
}
}
}