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Old 10-04-2006, 06:12 PM   #1
Theonewayman

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Real Time RayTraced Shadows
Hey guys i have downloaded a demo from the Humus site about real time RayTraced Shadows and humus says that only 7 spheres and a light source can be made in real time on "current" hardware, but i was having 300+ fps in the demo at 1280x1024, the demo is a realy tiny room with 7 spheres one as light source and they can be kicked around. I was so with the performance that i started thinking why arenīt game developers using this type of shadows in game engines, my hardware will be standard in two plus years x1900 XT, 1024 ram, AMDx2 4200+, so they could start making games with the option to use this type of shadows? I know that i canīt compare a demo with a real game, but a game is playable at 30 fps so for a game like a adventure or a indi type of game this kind of shadows IMO could be used, and they look like real shadows.

What you guys think? And post here how the demo runs on your machine.

Humus site: http://www.humus.ca/index.php?page=News

Humus demo link : http://www.humus.ca/3D/RaytracedShadows.zip

p.s Now that i think about it, is this in the right forum or would i post it on the general messages one?
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Last edited by Theonewayman; 10-04-2006 at 06:26 PM.
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Old 10-05-2006, 01:08 AM   #2
IHerman
Re: Real Time RayTraced Shadows
Well the demo you posted is quite old. It runs at 33fps on my x300 (at work, I wouldn't buy crap like that for my PC at home)

He's got some interesting stuff there, I remember the self shadowing bump mapping demo which I think is still kicking ass. Apparently not stuff you want to put in a game at them moment, because it kills fps.
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Old 10-05-2006, 06:01 AM   #3
Kristian Joensen

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Re: Real Time RayTraced Shadows
Wow that is pretty cool. Games these days take 4-5 years to develop. With this apperently running 33 fps on a X300 that surely should be more than enough to make this acceptaple for use in games that START development now and will be released in 2009-2010.

I mean even the X1900 series and the Geforce 7900 series will be low end by then. Even at the very bottom of the lowest low end.

Surely this could atleast be an OPTION in atleast CERTAIN situations by then.

However there is one thing that bothers my about these shadows aswell as all game shadows in general, that is that you can't see the surface they are cast upon through them.

Normal real life shadows are "see-through"(Translucent, I think is the proper english word). Does here know about any solution to that problem ? Perhaps a shadowing algorithm or modification to/variant of a current shadowing algoritm that solves that problem ?
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Old 10-05-2006, 08:26 AM   #4
Parkar

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Re: Real Time RayTraced Shadows
The shadows are not calculated using polygons at all so it only realy suports simple shapes. It could roughly be compared to a demo with 7 polygons. There is a pretty cool demo somewhere which is more like a real game that is completly ratraced (ie not just shadows). It also only has sphears but combines them to create creatures and level geometry. It only has hard shadows.

making the shadow not completly dark is probably easy. I think it generaly looks worse though as they look washed out since the shadow realy should be pitch black right next to the object and get less solid the further away you get.
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Old 10-05-2006, 09:50 AM   #5
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Re: Real Time RayTraced Shadows
Yeah, that demo is short-bus simplistic. If you were to add the props, actors, textures, etc from a AAA FPS title the framerate would commit suicide.

Cool none-the-less though.
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Old 10-05-2006, 06:36 PM   #6
Theonewayman

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Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Kristian Joensen View Post
However there is one thing that bothers my about these shadows aswell as all game shadows in general, that is that you can't see the surface they are cast upon through them.

Normal real life shadows are "see-through"(Translucent, I think is the proper english word). Does here know about any solution to that problem ? Perhaps a shadowing algorithm or modification to/variant of a current shadowing algoritm that solves that problem ?
On my end the shadows on the demo are not hardshadows but softshadows or as you put "see-though" shadows with a umbra and a penumbra as real life shadows, maybe your hardware is not rendering them as it should.

And yes there are solutions for the hardshadow problem as you can se on the new unreal engine 3 and on the crysis game, how they achive that i donīt know but none are so real as the ones on the demo.

Hudson as i said above for a simple game like a adventure and some small indi game this could be a good option. On my pc i was having 381 fps at 1280x1024 imagine what you could put in the demo until you reach 30 fps.
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Old 10-05-2006, 06:44 PM   #7
Theonewayman

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Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Parkar View Post
The shadows are not calculated using polygons at all so it only realy suports simple shapes. It could roughly be compared to a demo with 7 polygons. There is a pretty cool demo somewhere which is more like a real game that is completly ratraced (ie not just shadows). It also only has sphears but combines them to create creatures and level geometry. It only has hard shadows.

making the shadow not completly dark is probably easy. I think it generaly looks worse though as they look washed out since the shadow realy should be pitch black right next to the object and get less solid the further away you get.
So you are saing that the spheres and the walls of the demo donīt have polygons. So isnīt this demo runing on the GPU?

About the demo that you are talking isnīt it the FAN (Federation against Nature) one? If not can you give me a link?
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Old 10-06-2006, 12:50 AM   #8
Kristian Joensen

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Re: Real Time RayTraced Shadows
"On my end the shadows on the demo are not hardshadows but softshadows"

They are soft-shadows for me too, that is not at all what I am talking about. I am talking aout the fact that in real life if say a shadow is cast on the ground you still see the ground. In games usually you wouldn't see the ground but only a very dark shadow, instead of the ground.

What I am saying is that shadows in reality are semi-transparent. This has got nothing to do with them beeing soft, you could have semi-transparent hard edged shadows.

What I am saying is that I want shadows that are not only soft edged but also semi-transparent.

I have never seen such shadows in any game, engine or demo before. That is until yesterday when I downloaded 3D Mark 2006. In the demo there I saw some semi-transparent shadows.

Edit:

"And yes there are solutions for the hardshadow problem as you can se on the new unreal engine 3 and on the crysis game, how they achive that i donīt know but none are so real as the ones on the demo."

Yes I know that, it is also known how Epic does its shadows in Unreal Engine 3(But AFAIK not how CryTek does them in Crysis), this is taken form the Unreal Technology page:

Quote:
# Support for all modern per-pixel lighting and rendering techniques including normal mapped, parameterized Phong lighting; custom artist controlled per material lighting models including anisotropic effects; virtual displacement mapping; light attenuation functions; pre-computed shadow masks; directional light maps; and pre-computed bump-granularity self-shadowing using spherical harmonic maps.
# Advanced Dynamic Shadowing. Unreal Engine 3 provides full support for four shadowing techniques:

* Dynamic stencil buffered shadow volumes supporting fully dynamic, moving light sources casting accurate shadows on all objects in the scene.
* Dynamic characters casting dynamic soft, fuzzy shadows on the scene using 16X-oversampled shadow buffers.
* Ultra high quality and high performance pre-computed shadow masks allow offline processing of static light interactions, while retaining fully dynamic specular lighting and reflections.
* Directional Light Mapping enables the static shadowing and diffuse normal-mapped lighting of an unlimited number of lights to be precomputed and stored into a single set of texture maps, enabling very large light counts in high-performance scenes.
So they are using a combination of different things. In other words they haven't got a unfied system. They also don't use soft shadows exlusively as the first point shows.
Last edited by Kristian Joensen; 10-06-2006 at 12:56 AM.
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Old 10-06-2006, 01:10 AM   #9
theHunted
Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Theonewayman View Post
So you are saing that the spheres and the walls of the demo donīt have polygons. So isnīt this demo runing on the GPU?
The spheres obviously have to be made up of polygons to be rendered, but the shadow calculation is most likely not based on those polygons. That's just an assumption as I haven't seen the source code yet. But unless this is an actual stress test the whole thing is most likely just using the sphere parameters [position, radius] to calculate an intersection with a ray of light. That's what every raytracer does to handle spheres.
So calculating the shadow for one pixel in the screen of one sphere using this method roughly equals the same test with just one "polygon"-triangle.
The problem with the sphere parameters is that the test obiously doesn't generalize to random shapes. In the end you'd have to go back to intersection tests with triangles which means thousands of intersection tests for regular game geometry per pixel.
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Old 10-06-2006, 01:22 AM   #10
Kristian Joensen

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Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Kristian Joensen View Post
"On my end the shadows on the demo are not hardshadows but softshadows"

They are soft-shadows for me too, that is not at all what I am talking about. I am talking aout the fact that in real life if say a shadow is cast on the ground you still see the ground. In games usually you wouldn't see the ground but only a very dark shadow, instead of the ground.

What I am saying is that shadows in reality are semi-transparent. This has got nothing to do with them beeing soft, you could have semi-transparent hard edged shadows.

What I am saying is that I want shadows that are not only soft edged but also semi-transparent.

I have never seen such shadows in any game, engine or demo before. That is until yesterday when I downloaded 3D Mark 2006. In the demo there I saw some semi-transparent shadows.

Edit:

"And yes there are solutions for the hardshadow problem as you can se on the new unreal engine 3 and on the crysis game, how they achive that i donīt know but none are so real as the ones on the demo."

Yes I know that, it is also known how Epic does its shadows in Unreal Engine 3(But AFAIK not how CryTek does them in Crysis), this is taken form the Unreal Technology page:



So they are using a combination of different things. In other words they haven't got a unfied system. They also don't use soft shadows exlusively as the first point shows.
There is a part I accidently ommited from my quote from the Unreal technology page:

Quote:
  • All of the supported shadow techniques are visually compatible and may be mixed freely at the artist's discretion, and may be combined with colored attenuation functions enabling properly shadowed directional, spotlight, and projector lighting effects.
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Old 10-06-2006, 05:53 PM   #11
Theonewayman

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Re: Real Time RayTraced Shadows
We must not seing the same thing, because what i see on my PC is this.
Quote:
What I am saying is that I want shadows that are not only soft edged but also semi-transparent.
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Old 10-07-2006, 03:35 AM   #12
Kristian Joensen

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Re: Real Time RayTraced Shadows
That is exactly what I am seeing. You must not be understanding me. Look at those shadows on the wall, can you see the wall texture itself where the shadows is ? No, that is what I am getting at.

In real life you would see the wall "texture" itself also in the region where that shadow is. You don't do that in this little demo(Or any upcoming game/engine that I know of).
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Old 10-07-2006, 04:24 AM   #13
theHunted
Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Kristian Joensen View Post
... . Look at those shadows on the wall, can you see the wall texture itself where the shadows is ? ....
I do, actually. How can you not see it? I thought it was already clear to see on the above screenshot but maybe this one will help you out even further:

http://grazer.fichtenmoped.at/misc/rt_shadows1.jpg

Working with pixel shaders it shouldn't really be a big technical problem neither as far as i can make this up. You have full access to the color of the texture at a given pixel on the screen and then you probably just do the necessary calculations to find out whether or not the pixel is in the shadow region or not. In case it is in the shadow: just darken the texture color and apply it to the screen. Might be wrong, but I think this should work for a simple version.
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Old 10-07-2006, 04:48 AM   #14
Kristian Joensen

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Re: Real Time RayTraced Shadows
That is still completely dark. In your picture you say "darkened original texture" but my point is that it is darkened to the point that you can't recognize anymore.
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Old 10-07-2006, 05:31 AM   #15
theHunted
Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Kristian Joensen View Post
That is still completely dark. In your picture you say "darkened original texture" but my point is that it is darkened to the point that you can't recognize anymore.
Okay, at least you're not saying the shadow area is completely black and without structure at all. I thought that's what you thought until now
Talking about those shadows being completely dark as you say might be more of a philosophical thing or a thing of flavours. I for one wouldnt call it completely dark and i would also say that you still see a fair share of the original texture below it. especially the seams and cracks which are an important part of the texture.

Anyways, I'm only guessing here, but i am thinking you could just light up the shadows in this demo easily. The fact that you can actually see a little bit of the original texture (just very dark), means that it is the actual texture that gets darkened by some factor. One would just have to alter the lighting or shadow equation a little bit to get shadows that are not as dark and thus show more of the original texture. So this is not a technical problem but an artistic one. I figured that graphics programmers like to exaggerate their effects so they stand out and everybody notices them. The same thing happend with all existing implementations of normal mapping I've seen so far imo. No matter what material they're applied to, they always produce overbright highlights and extremely dark shadows so that you actually notice the effects. That's why I think all existing implementations of normal mapping suck, speaking from the view of an artist. Damn, where am I taking this thread?

Without going too much into detail i'd still like to point out that there seems to be just 1 light-source in that scene. In real-life your shadows might look brighter because there's not 1 but a large number of lightsources. Even if you just turn on 1 light bulb in your living-room there's still a lot of light coming from outside the window (even with blinds and possibly also at night), from other rooms, from electrical devices and other light-emitting objects.
But if you'd stand in a completely sealed and dark room and would just turn on 1 single bulb then i bet the shadows would look similar to the demo. We could now start arguing about the overall lighting being a bit too bright for a single lightsource...
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Old 10-07-2006, 05:46 AM   #16
rg3
Re: Real Time RayTraced Shadows
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Originally Posted by Kristian Joensen View Post
I have never seen such shadows in any game, engine or demo before. That is until yesterday when I downloaded 3D Mark 2006. In the demo there I saw some semi-transparent shadows.
Severance: Blade of Darkness had this quite long ago. Its physics engine and shadows were amazing for the time. And it ran fine on a TNT(2?) card.
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Old 10-07-2006, 06:28 AM   #17
Kristian Joensen

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Re: Real Time RayTraced Shadows
Yeah I have heard that game mentioned again and again, but I never actually played it. I will go look for screenshots on Google. It seems to have been quite a revolutionary game technology wise.

It is funny that you mention a TNT 2 since I myself have one in my older computer.
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Old 10-07-2006, 06:45 AM   #18
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Re: Real Time RayTraced Shadows
Quote:
Without going too much into detail i'd still like to point out that there seems to be just 1 light-source in that scene. In real-life your shadows might look brighter because there's not 1 but a large number of lightsources. Even if you just turn on 1 light bulb in your living-room there's still a lot of light coming from outside the window (even with blinds and possibly also at night), from other rooms, from electrical devices and other light-emitting objects.
But if you'd stand in a completely sealed and dark room and would just turn on 1 single bulb then i bet the shadows would look similar to the demo. We could now start arguing about the overall lighting being a bit too bright for a single lightsource...
Bingo

Quote:
Severance: Blade of Darkness had this quite long ago. Its physics engine and shadows were amazing for the time. And it ran fine on a TNT(2?) card.
Yes i know iīm a real fanboy of that game, but the shadows used in BOD are just Stencilshadows like the ones in doom3. And for the record BOD was the first game to use them, to have physics and also a water surface that mirror the sarroundings this in a game made in 1998/2001.
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Old 10-07-2006, 06:56 AM   #19
Kristian Joensen

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Re: Real Time RayTraced Shadows
Why do you put "1998/2001" as the year the game was made in ? Was it 1998 or 2001 ?
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Old 10-07-2006, 04:15 PM   #20
rg3
Re: Real Time RayTraced Shadows
I think it took several years to complete. From 1998 to 2001, probably. And, furthermore, it was one of the few sucessful games made in Spain (the Spanish videogame industry is very, very small). The other known Spanish games are probably the Commandos series.
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Old 10-07-2006, 09:08 PM   #21
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Re: Real Time RayTraced Shadows
I saw that game very recently, only for the reason so many people talked about it. It had unified stencil shadows .... which was a rare thing those days. It had nice water effects in comparison to when it was released. It had gigantic open areas which doesn't look too limited in comparison to when it was released. About the lighting, I think it was vertex lit throughout and maybe vertex coloring was also used to make things interesting, but I'm not sure. PLUS it was really smooth. PLUS PLUS it runs very well on XP or XP SP2 in comparison to all those games of that age. PLUS PLUS PLUS your levels depend on which player (among 4) you choose to play with in the begining.

So guys check this out ASAP.

Edit: I forgot to mention that the water was really interesting. It looked like 'turbulent' stencil reflection .... and actually looks much better than one of these present-day RTT water reflections. But it had a flaw which I'm not gonna mention just so maybe you guys won't notice if I dont. But if you do, don't tell here.
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Old 10-08-2006, 01:38 PM   #22
Theonewayman

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Re: Real Time RayTraced Shadows
Quote:
I think it took several years to complete. From 1998 to 2001
Yes, and it came out realy not finiched as you can see on the multiplayer part of the game.

Quote:
Originally Posted by Sayantan View Post
I saw that game very recently, only for the reason so many people talked about it. It had unified stencil shadows .... which was a rare thing those days. It had nice water effects in comparison to when it was released. It had gigantic open areas which doesn't look too limited in comparison to when it was released. About the lighting, I think it was vertex lit throughout and maybe vertex coloring was also used to make things interesting, but I'm not sure. PLUS it was really smooth. PLUS PLUS it runs very well on XP or XP SP2 in comparison to all those games of that age. PLUS PLUS PLUS your levels depend on which player (among 4) you choose to play with in the begining.

So guys check this out ASAP.

Edit: I forgot to mention that the water was really interesting. It looked like 'turbulent' stencil reflection .... and actually looks much better than one of these present-day RTT water reflections. But it had a flaw which I'm not gonna mention just so maybe you guys won't notice if I dont. But if you do, don't tell here.
Glad you like it Satan, it was one of the first games i played and made me like games in general. ho and satan about the water flaw is just a litle glitch. Also for all of the BOD players donīt forget to play the Uncle Pro (Prospero) mods the fugitive series, they have the same quality as the developers quests. You can find the mods on MODDB and the forum on my sig.
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Old 10-09-2006, 09:18 PM   #23
Sayantan

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Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Theonewayman View Post
ho and satan about the water flaw is just a litle glitch.
I don't think that's a glitch. If it was somehow fixed, the allover calculation would increase immensely. Hence it just used multiple passes for seperate objects which was actually a vertex shader thingy.
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Old 10-10-2006, 09:22 AM   #24
Kristian Joensen

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Re: Real Time RayTraced Shadows
Speaking about raytracing here is a "real-time" raytracing demo.
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Old 10-23-2006, 07:18 PM   #25
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Re: Real Time RayTraced Shadows
I could see the wall much better behind the shadow when I ran the demo. I got 88 FPS on my 6800, I think I was running higher settings than you though Onewayman, your screenshot didn't look too good.

That site is cool. It would be even better if the enviornments didn't look so old.
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Old 10-24-2006, 07:06 AM   #26
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Re: Real Time RayTraced Shadows
Quote:
Originally Posted by Kristian Joensen
That is still completely dark. In your picture you say "darkened original texture" but my point is that it is darkened to the point that you can't recognize anymore.
Kristian, those shadows are completely translucent and you can clearly see the wall and floor texture behind them. Please turn up your monitor brightness, it's the same reason why you think your avatar blends into the foorum color when it actually does not.
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