POV-Ray : Newsgroups : povray.general : normal average bug Server Time
14 Aug 2024 01:15:13 EDT (-0400)
  normal average bug (Message 1 to 2 of 2)  
From: PoD
Subject: normal average bug
Date: 28 Apr 1998 15:31:14
Message: <35462E82.380E@merlin.net.au>
Hi all,
        I think I've just found a bug in POV-Ray 3.02. I'm running the
windoze
version under Win95.
If you rotate an object with a normal{ average normal_map{}} then
rotating the object seems to affect the normal.
In the example below, in and out seem to be reversed when the object is
rotated 180 degrees around the z axis.
The top two cylinders have a simple normal.
The bottom two have the same normal as the only entry in an average.

(there's a picture in binaries.images)

Anyone seen this effect? Know how to fix it?
Cheers, PoD.

#include "colors.inc"

camera{ right 4/3*x direction z*3 location <0,0, -30> look_at <0,0,0> }

light_source{ <1000,2000,-5000> White }

#declare Norm1 = normal{radial .5 frequency 16 scallop_wave}
#declare Norm2 = normal{ average normal_map{[1 Norm1]}}
#declare Obj1 = cylinder{-y,y,1 pigment{White}  normal{Norm1}}
#declare Obj2 = cylinder{-y,y,1 pigment{White}  normal{Norm2}}

object{ Obj1 translate <-1.5,1.5,0> }
object{ Obj1 rotate z*180 translate <1.5,1.5,0> }
object{ Obj2 translate <-1.5,-1.5,0> }
object{ Obj2 rotate z*180 translate <1.5,-1.5,0> }

union{
        cone{ <1.5,-3,0>,0, <1.5,-3.5,0>,.5 }
        cylinder{ <1.5,-3.5,0>,<1.5,-4,0>,.25 }
        scale<1,1,.1>
        pigment{White}}


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From: Nieminen Mika
Subject: Re: normal average bug
Date: 29 Apr 1998 13:23:31
Message: <6i7nmj$avj$1@oz.aussie.org>
PoD (pod### [at] merlinnetau) wrote:
:         I think I've just found a bug in POV-Ray 3.02.

  I have noticed this bug too. Just see
http://www.iki.fi/warp/pics/Spacedog_4.jpg
  See the vertical dark stains in the border of some bricks? There shouldn't
be any. I used averaged textures on the wall, and the averaged normals
don't work as expected (the bricks far apart from the light are correct,
but the bricks near the light are not).

--
                                                              - Warp. -


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