Re: Kajiya-Kay Hair Light Model

Matt,

With some help from a friend (thanks Rob), I believe we've got it.

The numerator is,
Kd * l . [ l - (t.l) * t ]

= Kd * [ l.l - l.((t.l)*t) ]
= Kd * [ 1 - (t.l) * (t.l) ]
= Kd * [ 1 - (t.l)^2 ]

The denominator is,

| l - (t.l) * t |
= sqrt( [ l - (t.l) * t ] . [ l - (t.l) * t ] )
= sqrt( l.l - 2 * l.((t.l)*t) + ((t.l)*t).((t.l)*t) )
= sqrt( 1 - 2 * (t.l) * (t.l) + (t.l) * (t.l) * 1 )
= sqrt( 1 - (t.l)^2 )

Does this look correct to you?

.

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