erich@eye.com (Eric Haines) (05/23/91)
Archive-name: graphics/raytrace/spd/1991-05-21 Archive: weedeater.math.yale.edu:/pub/SPD.3.0.shar.Z [130.132.23.17] Original-posting-by: erich@eye.com (Eric Haines) Original-subject: Re: Newell's teapot in DKBtrace? Reposted-by: emv@msen.com (Edward Vielmetti, MSEN) In article <JRM.91May20122241@delta.ma.adfa.oz.au> jrm@delta.ma.adfa.oz.au (John R Marley) writes: > >I have DKBtrace version 2.11 running on our Apollo DN10000 and wish to trace a >few teapots. I have the data describing the thing, but it uses Bezier patches. >I can convert the Bezier patches to heaps of smooth shaded triangles, but >calculating the vertex normals will be a bit of a #$%^&*. It's not that hard to compute the normals - two more power vectors to get surface tangent u & v vectors, then take the cross product of these to get the normal. Things do fall apart at the center of the lid, where the normals go to zero or somesuch (I solve this by just testing for these special case guys). The code is a part of the SPD 3.0 package, which generates the teapot at any resolution you like. The SPD package is available via anonymous FTP from: weedeater.math.yale.edu [130.132.23.17] among others. For those without FTP access, write to the netlib automatic mailer: research!netlib and netlib@ornl.gov are the sites. Send a one line message "send index" for more information, or "send haines from graphics" for the latest version of the SPD package. It'll automatically send you the source. Eric -- comp.archives file verification weedeater.math.yale.edu -rw-r--r-- 1 ftp guest 47883 Dec 18 10:55 /pub/SPD.3.0.shar.Z found spd ok weedeater.math.yale.edu:/pub/SPD.3.0.shar.Z