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D-clone

Doom 3 looks great, but look at theese

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http://www.vrayrender.com/gallery/

look at the cars or the golfball.

I guess the answer is raytracing. Note to graphicgeeks: When do you think raytracing will make it to games?

Also heard Carmack will retire after another engine. Do you think iit might incorporate raytracing?

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This has nothing to do with Doom 3. To EE with you.
On topic: I don't know if it's the artwork or the dark atmospheric environment, but IMO Doom3 looks a lot better than that. (Not necesarily more realistic, but better)

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I would like to know what exactly ray-tracing is. I don't really get it. What does it do? And most important, are there any before/after pictures out there? I'd like to see the difference.

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Heh, I don't remember exactly, and I don't know the details, but ray-tracing is a rendering technique which simulates light hitting the object and being reflected off. It's a very realistic lighting system, basically, because every surface reflects light the way it wuld in real life, and it's also very good for shadows. The trick is that simulating light like that is very processor-intensive, and it can't be done in real-time yet.

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Raytracing is also best for realistic refractions. Note that raytracing is ancient technology by graphics standards. It's been around for over a decade. There are other techniques. But using ratracing is the easiest, at the cost of rendering time.

By the way, this is an external renderer for use with 3d modeling software. It has nothing to do with video games. You're basically comparing doom3 to something like Monsters Inc. The two are unrelated.

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Assmaster said:

Note that raytracing is ancient technology by graphics standards. It's been around for over a decade.

Yeah, didn't Myst and Riven use pre-rendered raytraced graphics?

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Listen to Assmaster. He is right. This is NOT used for real-time rendering like most game engines make use off. These renders can take for hours/days. But with a nice results.

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Zoost said:

Listen to Assmaster. He is right. This is NOT used for real-time rendering like most game engines make use off. These renders can take for hours/days. But with a nice results.

So is there a ray-tracing like technology which can render frames a lot faster? Something we might be able to use in videogames in the years to come?

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Space Hulk (2nd one) used raytracing. That was back in the days when the Saturn was still semi-cool. But, how exactly does raytracing work again? Doesn't it account for every beam of light, and render objects with reflection?

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Pure raytracing isn't the ultimate solution anyway, since it doesn't do soft shadows. Radiance is a nice open source package (funded by the Swiss government and NASA, among others) that aims to simulate real lighting as much as possible.

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Raytracing works by shooting out a beam of light for every pixel on screen. If the beam hits a brick, that color is sent back to the pixel. If it hits a mirror, it bounces until it hits a solid surface and that color is returned. You can do fancy things with glass windows, like have two beams shoot off (one for reflection, one for the light that goes through the window). It's a fairly easy concept.

The big problem is that it's very slow, especially with large scenes with a lot of reflection/refraction/etc. The good news is that it doesn't depend on any special hardware, just pure CPU power. A couple of years back I heard of a "raytracing card" that was just a couple of DSP's on a board, in effect creating a miniature SMP system on a board. Once CPU's get so powerful that graphics cards become redundant, raytracing might be viable for games.

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TeamKill said:

Space Hulk (2nd one) used raytracing.

Heh, I remember that game.
When a game mentions raytracing, it means that some (or all) of the objects have been prerendered. A good example is resident evil. All the rooms (scenes really) use prerendered objects. Meaning that that they were rendered using a modeling program and then implemented essentially as bitmaps.

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Pre-rendered graphics can often look one hell a lot better than 3D graphics, and not just raytraced ones.

An excellent example (because they're both made by the same company) is Baldur's Gate 2 and Neverwinter Nights. The former, which uses pre-rendered is 2D, has some simply stunning looking locations, whilst the latter, which uses 3D graphic, is generally pretty bland. Even the BG2 people and monsters look better than the NWN ones.

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with the number of passes that doom 3 is doing for every pixel, the next step for graphics engines could very well be ray-tracing, considering how generalized the shader instructions are getting

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mewse said:

with the number of passes that doom 3 is doing for every pixel, the next step for graphics engines could very well be ray-tracing, considering how generalized the shader instructions are getting

It'd be interesting to see how the media would handle a Doom remake with such an advanced engine. So other than ray-tracing, what else is missing that makes a game still looke like a game instead of a real life situation?

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The obvious answer to that is that all graphics currently appear in front of us on flat surfaces. Sure you can get that 180-degrees or whatever it is thingy, but ideally we need some way to get them to completely surround us and not appear flat.

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I remember playing with raytracing programs back in the P100 days. They are slooooow! To do a nice render of a textured sphere could take a 266MHz box 30 seconds. You could just watch it rendering pixel by pixel from the top down. Some of those pics you see on sites will have taken a week to do the final render.

Raytracing is how all the static lightmaps are done for games like Quake, Half-Life, etc. It was vastly simplified for this purpose though. All the info on polygon visibility comes from the VIS program and then the RAD program goes does it's raytracing trick for all the lights in the map using the data on polygon visibility. Surface reflections aren't based on the surface properties at all; there's just a static number of reflections you specify (default is 3). The more you have, the less harsh the shadows in an area are. All the jagged shadows are do to inaccuracies in the VIS data and the light goes through the doors because it has to be static and usually would look weird if it was always blocked (this is a setting too). Pseudo-dynamic lights probably could have been done with shadows if lightmaps of different combinations were compiled. Would be a neat experiment actually.

As for other things games could try to look more realistic, there are things like drawing smooth curves from all those polygons, like most of those fancy packages with raytracing do. Having zombies without pointy heads would be cool. Proper fog would also be nice. Most games just layer some colour over the image and it gets thicker as the area gets deeper. This looks like crap half the time because it acts like night vision in distant areas when it should be dark unless there's a light behind it. Some new engines like Tenebrae have done much nicer fog. Hopefully D3 and HL2 will have nicer fog (that's affected by shadows). I've still never seen fog cast a shadow though.

Water is usually done quite badly. DooM had awful water. Games like Quake and Half-Life had nicer water but the texture was usually really weird. The best animated water texture I ever saw was in Legacy before v1.30. It looked liquid. It got broken in newer versions though and they haven't put it back yet. Lots of GameCube games have awesome water but I haven't seen a lot of it in PC games yet.

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For some reason a lot of console games have good looking water effects with lots of reflecting, refracting, rippling, etc (see Ico for a great example), but they're pretty rare even in the most modern PC games.

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It is possible to do real-time ray tracing, by limiting the resolution and lighting complexity and a few other tricks. I've seen a few real-time demos that do this, complete with a form of anti-aliasing. Not running very fast, but it looks like ten 3D Studio Max renders a second.

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Yeah, Super Mario Sunshine and Star Fox Adventures both have really good water. The Resident Evil Remake for the Gamecube looks incredible. It's definately given me some inspiration for adding detail.

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The only other form of technology I can think of that could be added is radiosity. It's a way of accounting for the light that bounces off of an object. Dont ask me to explain further, as I'll likely get it wrong. I'm just a lowly graphics monkey :P

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Disorder said:

It'd be interesting to see how the media would handle a Doom remake with such an advanced engine. So other than ray-tracing, what else is missing that makes a game still looke like a game instead of a real life situation?


Global Illumination (radiosity), Soft shadows, more advanced materials, and all the polygons in the world:)

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Disorder said:

Do you have a link to one of those render demo's perhaps?


You can have a look overhere.

If you are interested in nice renders have a look ]here [cgtalk.com] with is a part of [cgnetworks.com] or here [polycount.com].

You will be amazed what some (sometimes extremely young) people can do!

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Assmaster said:

The only other form of technology I can think of that could be added is radiosity. It's a way of accounting for the light that bounces off of an object. Dont ask me to explain further, as I'll likely get it wrong. I'm just a lowly graphics monkey :P


Radiosity works in the opposite way from raytracing - it shoots beams of light from the light sources. This has several advantages, namely that it generates soft shadows and provides for more realistic lighting in a scene. Also, once the radiosity calculations are completed for a static scene, the end result can be stored and used for prerendered shadows in a scene - this is how games like Quake do shadows.

Unfortunately, doing the actual radiosity calculations is WAY more expensive than rayracing. This makes sense if you think about it: in ray tracing you only shoot out rays for each visible pixel on screen (so there is no wasted effort), while in radiosity you have to shoot out a ton of rays for every light source - even the ones that aren't directly visible (since you never know before hand if that light will contribute to the current visible scene).

There are, however, clever ways to get results similar to radiosity using raytracing - the RADIANCE project I linked to earlier is an excellent example. This project is actually used by NASA and various architects to model physically accurate lighting conditions, something that standard raytracing and radiosity is notorious for doing incorrectly (ie, they're only good for "pretty pictures").

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That guitar seems to be the most impressive, lifelike one there.

Is it just me, or does anyone else suspect that a handful of the images on that page are photographs? The screw on the table for one, the toy robot is another.

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