Ray Tracing And Gaming

HardOCP News

[H] News
Dec 31, 1969
PCPerspective has an introduction to ray tracing posted today that focuses on the Quake 4: Ray Traced Project but applies to ray tracing and gaming in general as well.

As a base for this project the content from “Quake 3” was used. It was amazing how easy it was to program special effects that would have taken much longer using the conventional graphic technology called “rasterization” used by common graphic cards.
Nice article. I remember there being a discussion about a RTPU in the PPU forum a while back.
The advantages of ray-tracing (RT) over rasterization are greatly exaggerated. Actually RT is not able to provide any better image quality except for shadows and reflections/refractions. Even for those, the new rasterization engines do very well while being several magnitudes faster. Moreover, refractions and reflections can be approximated using some shader tricks.
If you like the shadows on these RT images you'd better know that even the rasterization techniques would be able to provide that quality but because of performance trade-offs developers usually limit the shadow map resolution.

If you want proof just compare some Crysis engine screenshots with these Q3 & Q4 renderings. You'll see, that RT is totally not the future but more like an interesting toy for some phd student projects.

In fact RT is not the way to go for photo-realistic rendering. It is a common sense that its product looks always very synthetic, since it is unable to handle scattered light. Furthermore it's a misconception that all the CGI movies are rendered using RT exclusively. Actually, RT is used only for some specific scenes where high quality refraction/reflection is required. In other cases other methods, like radiosity provide much better result (sometimes combined with RT).
wow, zzebi you seem to know a lot about this. Do you work in the field? Why would ray-tracing not be able to handle scattered light?
Ever play a game where your light source bled thru a wall and the light kept going into the next room? Neverwinter Nights 1 and 2 are good examples of this.

With ray-tracing, you wouldnt see that happen anymore. Just one of many good things that incorporating ray-tracing would bring to game rendering.

What I'm curious about tho, is 1) can existing generation graphics cards do ray-tracing at all, or does it all have to be off-loaded to the CPU? and 2) how hard would it be to use a 'best of both worlds' solution, and use current rendering techniques with ray-tracing to provide the most realistic looking environment, without sacrificing speed?
This is hype about ray-tracing is going to a very wrong direction. What you need to understand is that the reason why the shadow rendering is not perfect in today's games is NOT that it cannot be done using rasterization but because the engines have to be optimized to reach high framerates and resolutions. By sacrificing framerate the best current game engines ARE able to produce ray-tracing quality shadows and near RT quality reflections/refractions while still being about 1000x faster than the fastest RT renderer.

For example there was a ridiculous image on the PC Perspective page about Far Cry that the trees was not reflected in the water. Come on.... the only reason why the trees were not there is that it would have reduced the framerate by what..... 20% (80fps instead of 100fps)?
In the same time, that scene in high resolution would take minutes to be computed using RT and it would be really hard to see the difference between the two results.

It makes sense, however, to use RT in some very limited situations. For example I can imagine a game where some scenes contain complex refractions/reflections that cannot be computed using pixel shaders. In this case RT could be used to compute only that small part of the image.
Actually, this is what most 3D animation softwares do. Even 3Ds Max uses RT only in some limited cases.