On Thu, 20 Aug 1998 22:27:58 +0200, Philippe Debar 
        <phi### [at] hotmailcom> wrote:
>Some answers to Ron Parker <35d9f8a6.0@news.povray.org>
>   >You can use .x and .y with 2-d vectors as well ...
>
>I just had a small battle with vector promotion and extraction. In v3.1b5,
>operator
>.v seems to invoke an error whenever it is used (2d or3d vectors). Promotion
>doesn't
>work as I thought it should :-) <3,4> + z doesn't output <3,4,1> (I think I
>got <3,3,3>,
>but I am not sure anymore).

The problem here isn't one of syntax but one of a broken expression parser
that doesn't handle 2d vectors properly.  I think it's finally been fixed.

>   >bounded and clipped light_source - What do you think the syntax should
>look like?
>
>Keep it simple and coherent, so something like:
>   light_source { 0, color rgb 1 clipped_by{sphere{0,100}} translate
>TheLight}
>seems to me to be the most logical.

Ah.  I see now that you and I have different views of what it means to clip
a light source.  I was wanting to clip them so that they only illuminate, 
say, the pyramidal area projected by a square cutout.  Such light sources 
could be used to simulate specular reflection from plane surfaces.

>   >special and spatial file format for image mapping -
>   >Have you played with using a density pattern in a pigment statement yet?
>
>Do you mean df3 files? If so, I'd like to, but I am lost at sea as how to
>generate
>them. The file format description in the doc is a bit to technical for me.
>If ever
>you know the location of a better description, let me know - thanks.

Yep.  I posted one a while back.  I think it may have been in 
povray.programming.

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