//3维点的长度的平方
public static float Vector3fLengthSquared( Tuple3fT NewObj)
{
return (NewObj.s.X * NewObj.s.X) +
(NewObj.s.Y * NewObj.s.Y) +
(NewObj.s.Z * NewObj.s.Z);
}
//3维点的长度
public static float Vector3fLength( Tuple3fT NewObj)
{
return Convert.ToSingle(Math.Sqrt(Vector3fLengthSquared(NewObj))) ;
}
//3维点点积
public static float Vector3fDot( Tuple3fT NewObj, Tuple3fT v1)
{
return (NewObj.s.X * v1.s.X) +
(NewObj.s.Y * v1.s.Y) +
(NewObj.s.Z * v1.s.Z);
}
//3维点矢积
public static void Vector3fCross(ref Tuple3fT NewObj, Tuple3fT v1, Tuple3fT v2)
{
NewObj.s.X = (v1.s.Y * v2.s.Z) - (v1.s.Z * v2.s.Y);
NewObj.s.Y = (v1.s.Z * v2.s.X) - (v1.s.X * v2.s.Z);
NewObj.s.Z = (v1.s.X * v2.s.Y) - (v1.s.Y * v2.s.X);
}
//鼠标拖动计算旋转
public void drag(Tuple2fT NewPt, ref Tuple4fT NewRot)
{
//新的位置
_mapToSphere(NewPt, ref EnVec);
//计算旋转
//if (NewRot)
{
Tuple3fT Perp = new Tuple3fT();
//计算旋转轴
CMatrixMath.Vector3fCross(ref Perp, StVec, EnVec);
//如果不为0
if (CMatrixMath.Vector3fLength(Perp) > CMatrixMath.Epsilon)
{
//记录旋转轴
NewRot.s.X = Perp.s.X;
NewRot.s.Y = Perp.s.Y;
NewRot.s.Z = Perp.s.Z;
//在四元数中,w=cos(a/2)，a为旋转的角度
NewRot.s.W = CMatrixMath.Vector3fDot(StVec, EnVec);
}
//是0，说明没有旋转
else
{
NewRot.s.X =
NewRot.s.Y =
NewRot.s.Z =
NewRot.s.W = 0.0f;
}
}
}
public void _mapToSphere(Tuple2fT NewPt, ref Tuple3fT NewVec)
{
Tuple2fT TempPt;
float length;
//复制到临时变量
TempPt = NewPt;
//把长宽调整到[-1 ... 1]区间
TempPt.s.X = (TempPt.s.X * this.AdjustWidth) - 1.0f;
TempPt.s.Y = 1.0f - (TempPt.s.Y * this.AdjustHeight);
//计算长度的平方
length = (TempPt.s.X * TempPt.s.X) + (TempPt.s.Y * TempPt.s.Y);
//如果点映射到球的外面
if (length > 1.0f)
{
float norm;
//缩放到球上
norm = 1.0f / Convert.ToSingle(Math.Sqrt(length));
//设置z坐标为0
NewVec.s.X = TempPt.s.X * norm;
NewVec.s.Y = TempPt.s.Y * norm;
NewVec.s.Z = 0.0f;
}
//如果在球内
else
{
//利用半径的平方为1,求出z坐标
NewVec.s.X = TempPt.s.X;
NewVec.s.Y = TempPt.s.Y;
NewVec.s.Z = Convert.ToSingle(Math.Sqrt(1.0f - length));
}
}