When calculating the half vector, the vectors are both from the object to the eye or light.
That is, the half vector is created by adding the vector from the object to the light and the vector from the object to the eye.
Here, pay attention to only the V and the L vectors. V = View = Eye. The H vector is the half vector, half-way between the V and L vectors.
But notice that they all point away
from the surface. Towards
the eye and the sun/light.
Some people think better when visualizing the sun vector (or light vector of any kind) as going out of the sun in some direction.
Those people need to reverse the sun’s direction for lighting equations, because that line of thinking makes the L vector point towards the surface.
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