public static Transform2D Scale (float x, float y)
{
var t = new Transform2D ();
t.M11 = x;
t.M22 = y;
//t.M33 = 1;
return t;
}
public static Transform2D Translate (float x, float y)
{
var t = new Transform2D ();
t.M11 = 1;
t.M22 = 1;
//t.M33 = 1;
t.M13 = x;
t.M23 = y;
return t;
}
public Transform2D Invert ()
{
// [ M22, -M12, M12*M23 - M13*M22;
// -M21, M11, -M11*M23 + M13*M21;
// 0, 0, M11*M22 - M12*M21]/(M11*M22 - M21*M12)
var d = M11 * M22 - M21 * M12;
if (d == 0)
throw new InvalidOperationException ();
var r = 1.0f / d;
var t = new Transform2D ();
t.M11 = r * (M22);
t.M12 = r * (-M12);
t.M13 = r * (M12 * M23 - M13 * M22);
t.M21 = r * (-M21);
t.M22 = r * (M11);
t.M23 = r * (-M11 * M23 + M13 * M21);
return t;
}
public static Transform2D Identity ()
{
var t = new Transform2D ();
t.M11 = 1;
t.M22 = 1;
//t.M33 = 1;
return t;
}
public static Transform2D operator * (Transform2D l, Transform2D r)
{
var t = new Transform2D ();
t.M11 = l.M11 * r.M11 + l.M12 * r.M21;// +l.M13 * r.M31;
t.M12 = l.M11 * r.M12 + l.M12 * r.M22;// +l.M13 * r.M32;
t.M13 = l.M11 * r.M13 + l.M12 * r.M23 + l.M13;// *r.M33;
t.M21 = l.M21 * r.M11 + l.M22 * r.M21;// +l.M23 * r.M31;
t.M22 = l.M21 * r.M12 + l.M22 * r.M22;// +l.M23 * r.M32;
t.M23 = l.M21 * r.M13 + l.M22 * r.M23 + l.M23;// *r.M33;
//t.M31 = l.M31 * r.M11 + l.M32 * r.M21 + l.M33 * r.M31;
//t.M32 = l.M31 * r.M12 + l.M32 * r.M22 + l.M33 * r.M32;
//t.M33 = l.M31 * r.M13 + l.M32 * r.M23 + l.M33 * r.M33;
return t;
}