In 2D canvas the origin is at the top left hand corner at this position x = 0 and y = 0. The value of x increases as it moves towards the right horizontally. The value of y similarly increases as vertically down.
In 3D canvas the origin is in the center , at this position x = 0, y = 0 and z = 0. An object can move in three coordinates x-axis,y-axis and z-axis.
On the x-axis horizontally, as the object moves towards the left side the negative values increases while on the right side the positive values increases .
On the y-axis vertically,as the object moves up the negative values increases and as it moves down the positive values increases.
On the z-axis diagonally, as the object moves closer the positive values increases while as it moves away the negative values increases.