Notice a "vertical" pin to the horizontal plane of the ground or floor...
Thus what's called a Horizontal Hinge...

Notice a "vertical" pin to the Inclined Plane...
Thus what is called An Angled Hinge...

Notice a "vertical" pin to the Vertical Plane of the wall
Thus what is called a Vertical Hinge...

Pins are always vertical to what ever plane they are associated to...the blade swings in a circle around the pin ....the motion of the blade represents the motion of it's plane ...the associated plane