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Argent Stonecutter
Emergency Mustelid
Join date: 20 Sep 2005
Posts: 20,263
11-26-2005 08:51
From: AJ DaSilva
What I can say though, is that Doom style rendering doesn't use polygons (in the triangle sense). It doesn't have lighting either (each section is set to a brightness manually). It's actually a realy simplistic engine compared to current stuff: each map was constructed from 2D vectors (not sure that's the right term, but still...) with height values for each segment.
I'll have to look at Doom again, but it looked like it was just drawing polygons (rectangles) in reverse distance order and double-buffering that. The "mesh", such as it is, is manually created with one rectangle per wall segment. All modern renderers I know of use triangular meshes because it's easy to generate and it's easy to do the kind of simple lighting they use on triangles, but when you're doing all that stuff by hand you can use anything you want.

The early raytracers actually used spheroids for the "mesh" because intercept calculations were easy and when you're spending 10 hours to generate a frame with three objects in it you REALLY want to make 'em easy! That's why early PC raytraced figures, like the guy in the Amiga "Juggler" demo, all looked like the Michelin Man.
Alex Lumiere
Registered User
Join date: 1 Jun 2004
Posts: 228
11-26-2005 08:56
if i remember correctly, someone made a real mirror about a year ago. People were quite impressed. Do a search.
AJ DaSilva
woz ere
Join date: 15 Jun 2005
Posts: 1,993
11-26-2005 09:20
From: Alex Lumiere
if i remember correctly, someone made a real mirror about a year ago. People were quite impressed. Do a search.
That'll probably be Bravo Bravo's that Yumi Murakami was talking about back in post 14. I think it's been done by a couple of other people too.
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Lavanya Hartnell
Registered User
Join date: 9 Dec 2005
Posts: 55
Mirrors sighted
05-03-2006 09:07
I have seen mirror effects in several places. I have not yet been able to reproduce it, though. The first time was at a sim that had puddles of prim water refelcting the buildings etc in them. Mind-blowing, because I thought it impractical, too.

One thing I have noticed that I suspect is key is that the mirror surfaces are always orthogonal -- at right angles to the world. The puddle on the ground, a mirror on a wall, and so on; they were all at perfect right angles.

I suspect that if OpenGL doesn't support mirrors (I doubt it), what SL may be doing is a second rendering from a different camera angle and simply mapping the rendering onto the mirror's surface. It's not hard; just doubles the computations. It's probably easier when it's orthogonal, though; there may be a shortcut to speed computation.

Still searching. I'll probably find it when I find Bigfoot.


- Lavanya
AJ DaSilva
woz ere
Join date: 15 Jun 2005
Posts: 1,993
05-03-2006 09:17
Lavanya,

The puddles and mirrors you've seen have been created by modelling the scene in front of the mirror behind it, but in reverse. Try swinging your camera underneath the puddles to see what I mean. It should be possible to create these at any angle you like.

I'm afraid the only real way to create a dynamic mirror in SL currently is to reverse and stream the rendered view from an avatar as a media texture, with a scripted camera to change the view depending on where the viewer's camera is, and then you can only have it correct for one person.
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Sean Martin
Yesnomaybe.
Join date: 13 Sep 2005
Posts: 584
06-22-2006 20:42
From: AJ DaSilva
Actually, I was saying I was afraid it's impossible (afraid as in sorry).

There's no way to do an actual reflection that would show avatars, and making one that reflects prims would:
a) require a space behind it equal to that which is being reflected in front of it (i.e. the entire room)
b) be incredibly hacky and difficult to make dynamic (one that isn't dynamic can be crated by modelling)

It's very possible.
Just not in SL.
yet :p
Look at other games like GW.
I've been doing a little reading up on it since the subject has came up in another post somewhere. But I have no clue how it works really.
I only know how rendering works like in Maya or Bryce.
It seems in some games they map the image using openGL, I'm guessing its something like ray tracing, and others use a prerender. But that would lag the client down either way.
I'm not sure thou. Interesting stuff.

In gw they have flex prims also. And the reflections are mirroring those dynamic flex prims exactly.

And of course there is the old way to make a secondary world behind the mirror like you said.
I remember an old 3D mario game that tried something along those lines. :rolleyes:
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Keknehv Psaltery
Hacker
Join date: 11 Apr 2005
Posts: 1,185
06-23-2006 11:04
The most common way for things to have reflections nowadays is to use environment mapping, that is, the scene gets rendered from the reflective surface's POV, and then when the overall scene is rendered, the texture on the mirror is the appropriate color for each point of the mirror. This makes LOD systems and culling much harder. SL probably doesn't need mirrors, not when the rest of the rendering system is so relatively primitive.
AJ DaSilva
woz ere
Join date: 15 Jun 2005
Posts: 1,993
06-23-2006 12:15
Dredging up an old thread and then not reading it... what's the world coming to?

Anyway, I haven't tried it yet but I was thinking and I reckon you could fake a mirror for one person using a second avatar with a scripted camera and then mirroring (cropping) and streaming the rendered view and putting it on the mirror's surface. Might work good enough to be used for machinima if it was streamed over a local network, but otherwise not of much use.

EDIT: Oh, I mentioned that before. :rolleyes:
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Drizzt Naumova
Teh Foxeh DJ
Join date: 9 Oct 2005
Posts: 116
06-23-2006 15:07
What i'm wondering is..how is the excellent reflections i might add done in devils moon. always been a fav place of mine :D
Love those puddle reflections
AJ DaSilva
woz ere
Join date: 15 Jun 2005
Posts: 1,993
06-23-2006 15:32
From: AJ DaSilva
The puddles and mirrors you've seen have been created by modelling the scene in front of the mirror behind it, but in reverse. Try swinging your camera underneath the puddles to see what I mean. It should be possible to create these at any angle you like.

.
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