Errata.GraphicsGemsIV

Errata to _Graphics Gems IV_, first edition, edited by Paul Heckbert,
Academic Press 1994.  Code available online at http://www.graphicsgems.org

compiled by Eric Haines (erich@acm.org) from author and reader contributions

version 1.5
date:  9/10/2008

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Errors in the text:

p. xvi, near the bottom of the page: change
    "in directory pub/GraphicsGems/GemsIV"
    to
    "in directory pub/Graphics/GraphicsGems/GemsIV".


p. 129, lines 4,7,10:  changes:
        "if (x < 0)" to "if (x >= 0)",
        "if (y < 0)" to "if (y >= 0)",
        "if (z < 0)" to "if (z >= 0)".

p. 138, first equation: change "(-ax,ay)" to "(-ay,ax)" to match the text.

p. 349, for (Moore 1992):  change "Rice University, Houston, TX" to "Cornell
    University, Ithaca, NY".

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The following are errors in the code listings (corrected in the online code at
princeton.edu:pub/Graphics/GraphicsGems/GemsIV).  Note that many of the code
listings online are different in minor and major ways from the code in the
book.


Serious errors (ones your compiler cannot or may not catch):

p. 273, 11 lines from the bottom:
        B[0], umid, u1, depthb,
    to:
        B[1], umid, u1, depthb,
    (thanks to Frank Rosfelder)

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Syntax errors (ones that are not usually harmful, or are easily caught):

[none so far]

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The following are errors in the comments:

p. 136, line 10: change
    "The N data points have indices which range from 0 to N-1."
    to "The data points have indices which range from 0 to N."
    (thanks to Michael Ford, 9/10/2008)

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A new point in polygon test has been added to ptpoly_haines/ptinpoly.c, a
variation on the Crossings test which is about 15% faster for triangles.
This CrossingsMultiply test avoids using division.

A potential divide by zero error has been removed from
ptpoly_haines/ptinpoly.c; line 1286 had "inv_y = tmax / ydiff;", which is
now deleted.

END