🚀 go-pugleaf

Much to my dismay and horror, I have discovered that the forces of evil
succeeded in introducing several errors in our paper "Fast Phong Shading"
in the SIGGRAPH'86 proceedings.  I am posting the corrections to the net
in hopes that they will get to most people who are interested in the
method before too many tears are shed.

Page 104, first column, first equation.
	Remove the |L| term from the denominator of the second term.  The
	equation should look like:

		         L     Ax + By + C
	I       (x,y) = --- . -------------
         diffuse        |L|   |Ax + By + C|

Page 104, first column, second equation
	Strike the L. from before the Ax, By and C terms in the denominator.
	The equation should look like:

                         L.Ax + L.By + L.C
	I       (x,y) = -------------------
	 diffuse	 |L| |Ax + By + C|

Page 104, second column, second equation
                                                                            2
	The first term in the numerator of the equation for T  should be 3cg 
               2                                             5
	not 3ig .  The equation should look like:

                 2
              3cg  - 4cdi - 4agi
	T  = --------------------
                2
              8i sqrt(i)

Page 105, first column, second equation
	
	The E in this equation is NOT the eye vector.  The (Dx + Ey + F) term
	is meant to interpolate H(x,y).  The D, E, and F in this equation are
	chosen, just as the A,B, and C for N, to interpolate the H vector over
	the polygon.

I am truly sorry for any grief that my errors may have caused anyone trying
to understand the method.  The errors are purely my own, I bear all the
responsibility.

Gary Bishop
AT&T Bell Labs
Holmdel, NJ 07733
(201) 949-3557