Re: [9fans] Attempt at making 3D graphics library

[Paul Lalonde <plalonde@telus.net>]

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It's hard to tell what might be wrong with your transformation if you  
don't also show the transformation matrix you are using, including  
the camera parameters.  What you probably want is for your transform  
to go from some world space coordinates (your 5,5,5) to screen  
space.  It's also not clear if you are expecting device coordinates  
(0..1023, 0..767) or normalized coordinates (0..1, 0..1).   Your  
resulting coordinates aren't too far off for some camera vaguely  
pointing at the origin and a device coordinate transformation matrix.

Paul


On 23-Nov-07, at 7:43 PM, Pietro Gagliardi wrote:

> Hello. I realized that that last /usr/glenda/bin/rc/pull focused on  
> a rewrite to the system libraries. I decided to start writing a  
> library to convert 3D coordinates to 2D coordinates based on the  
> data at http://www.shade.ca/getarticle.asp?i=11. You can find it  
> at /n/sources/contrib/pietro/3d.bundle. It contains: 3d.h (the  
> header), 3d.c (the library itself), and 3dtest.c (a test program).  
> The test program doesn't seem to work right. It looks like the 2D  
> coordinates are way off the charts - the x coordinates are between  
> 500 and 600 for xyz=(5,5,5)! I wonder... This makes the line a stub  
> in the center of a 1024x768 screen. Plus, the threadmain crashes on  
> threadexitsall. What's going on?
>

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