Path: chuka.playstation.co.uk!news
From: Ian Thompson <ianthomp@clara.net>
Newsgroups: scea.yaroze.programming.3d_graphics
Subject: Re: Calculating RSD Normals
Date: Sat, 09 May 1998 00:10:29 +0100
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Jar Williams wrote:

> I am just starting with Yaroze, but I have tried to make a similar
> converter, so I'll give it my best shot.
>
> As far as I can tell (please, anyone feel free to correct any mistakes!) the
> flat shading model calculates a single normal for each polygon. Try looking
> at PLY file that was generated by dxf2rsd. You will notice that there is one
> entry in the Normal section for every entry in the Polygon section (as long
> as the conversion.....

Hi Jar,

I still can't get it to work. Here is the code I produced based on your explanation.

   x1,x2,x3,y1,y2,y3,z1,z2,z3 are a triangle's vertices.

  nx = ((y2-y1)*(z3-z1))-((z2-z1)*(y3-y1));
  ny = ((z2-z1)*(x3-x1))-((x2-x1)*(z3-z1));
  nz = ((x2-x1)*(y3-y1))-((y2-y1)*(x3-x1));

  length = sqrt((nx*nx)+(ny*ny)+(nz*nz));

  nx=-nx/length;
  ny=-ny/length;
  nz=-nz/length;

Please correct me if I am wrong in the implementation.

Thanks for the help,

Ian T.