Re: About real-time reflections!

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Angus Dorbie (dorbie++at++bitch.reading.sgi.com)
Mon, 16 Dec 1996 12:16:26 +0000


On Dec 14, 2:46pm, Sunil S Hadap wrote:
> Subject: About real-time reflections!
> Hi, I am a new Performer mailing list member, I don't know whether this
> question is covered.
>
> For many days I am thinking about real-time reflections, how it is done!
> I am not talking about tricks like environment mapping or even
> multi-pass rendering in IR.

This is how it's always done. It's the only way in OpenGL.

> There are real-time reflections
> implementations in some products. One of them is by Clarus. The
> reflections on the car body and the reflective flooring is not due to
> environment mapping as it is dynamic. Meaning if you introduce any new
> geometry in the scene, it gets reflected. It is also not due to
> multi-pass rendering as there are too many reflecting surfaces and hence
> can not be done by multi-pass rendering.

You seem to have a limited definition of multi-pass. If you render the
scene to six frusta forming the complete cube from the centre of the
object it should be possible to read these into texture memory and use
a second pass to render an environment map (so far this is similar to
a dome distortion correction pass), this image then read into texture
memory and used as an accurate environment map which is used in the third
and final pass, rendering the scene from the eye.

>
> I searched a lot about this, even I have my own ideas about it. One of
> the idea is doing single-pass per-vertex raytracing in the scene. I just
> wonder is this sufficiently fast so that it can be done in real-time.

Possible but panfull, you'd have to implement a complete ray tracer with
all the texture and lighting calculations to match OpenGL & your database.

Cheers,
Angus.
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