Path: utzoo!attcan!uunet!mcvax!hp4nl!hpuamsa!marco
From: marco@hpuamsa.UUCP (Marco Lesmeister)
Newsgroups: comp.graphics
Subject: Re: Re: raytracing in ||
Message-ID: <7760002@hpuamsa.UUCP>
Date: 17 Nov 88 15:05:35 GMT
References: <1351@umbc3.UMD.EDU>
Organization: HP NL
Lines: 31

> 1) Given a pixel on the screen, there are an infinite number of light
>    rays that might hit it.  Does one only calculate the ray perpendicular
>    to the screen, or is that insufficient?  How many rays does one
>    calculate?

You calculate only the rays from the eye-point through each pixel, so
that's a ray per pixel.

> 2) From an intersection point, one sends a test ray directly at the light
>    sources to test for objects that might cast shadows.  What if you
>    are on the far side of an object from a light source?  

I tested the newly casted ray against all of the objects, and if the
intersection point is closer to the light-source than the first found
intersection point, the first found i.p. is not visible seen from the
light-source.
If the intersection point is on the back-end of an object seen from
the eye-point, then that is not a valid intersection point in the
first place.

> Sorry if these are amateurish questions, but I'm new at (and intensely
> interested in) this.

I know how you feel, because that's where I was about a year ago.

> -Scott Bodarky	          |	bodarky@umbc3 (UNIX)

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