xyShear about the Origin  2d and 3d transformations
Suppose an object point P(x,y) be moved to P'(x',y') as a outcome of shear transformation in both x and ydirections along with shearing factors a and b, respectively, as demonstrated in
The points P(x,y) and P'(x',y') have the subsequent relationship :
x' = x +ay


y' = y+bx

= Shxy(a,b)



(19)
Here ′ay′ and ′bx′ are shear factors in x and y directions, respectively. The xyshear is also termed as shearing for short or simultaneous shearing.
In matrix form, we contain:
(20)
In terms of Homogeneous Coordinates, we contain:
(21)
It is, P'_{h} = P_{h}.Sh_{xy}(a,b) (22)
Here P_{h} and P'_{h} represent object points, before and after needed transformation, in Homogeneous Coordinates and Sh_{xy}(a,b) is termed as homogeneous transformation matrix for xyshear in both x and ydirections along with shearing factors a and b, respectively, particular case: while we put b=0 in above equation (21), we contain shearing in xdirection, and while a=0, we have Shearing in the ydirection, correspondingly.