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View Full Version : Tim Sweeney Technical Q&A


jAkUp
06-06-05, 09:29 PM
Many of you watched the interview (http://www.nvnews.net/vbulletin/showthread.php?t=50895) that I had with Tim Sweeney at E3 2005 last month. He is an extremely nice guy, and I want to thank him for letting me ask a few more questions.

Intel17 wanted me to ask these few questions, Tim is a very busy man, so I think this is gonna be it :) I thought some of you guys would like to see this...

jAkUp- Can Unreal Engine 3 do full realtime shadowing support from all geometry, even with moving lights on static geometry instead of using stencils, like what JC talked about at his last years Quakecon speech? And can you scale up the samples to 64 or more on the buffers? Also, is pre-computation an option or is it done automatically by the engine?

Tim- Right now, stencil shadows are the only technique we're using for thefully general case of moving lights shadowing all kinds of geometry in the scenes, while shadow buffers are used on a per-object basis for self shadowing and world shadowing of single objects or small groups of objects. Our shadow buffer support supports cube map shadowing and can easily be extended (in C++ code) to handle the everything-shadowing-everything case, but then you run into all of the scaling and biasing issues of large-scale shadow buffer support requiring ultra high-res shadow buffers. I don't think that will be a desirable approach for another couple generations. The memory and fill rate requirements there are high even for next-gen consoles.

jAkUp- Would applying more samples to the shadowbuffers offset some of the limitations? Also, how many samples can be added in UE3? Is it arbitrarily selectable by artists or must new amounts of samples be coded in by programmers? And, can some of the problems with buffers being used everywhere be solved by a sharp modder or does Epic not supply enough source code for modders to do this? Finally, do you expect that UE3 can be modded to do what JC talked about at QuakeCon2004?

Tim- Adding more samples reduces aliasing, but doesn't increase the detail (or effective resolution) of the shadows so it doesn't solve all problems. We don't expose sample count to artists now but could if it turned out to be important. Modders will have access to the entire tool set that our artists use internally and all of the gameplay code, but we're not sure yet that we'll provide beyond that.

Clay
06-06-05, 09:36 PM
Thanks jAkUp! :thumbsup:

Intel17
06-06-05, 10:47 PM
Great job, and thanks Jakup!

For more Tim Sweeney interviewing, check out the one I conducted with him a few hours ago at http://www.beyond3d.com/forum/viewtopic.php?t=23763

nVidiaGuru
06-07-05, 12:57 AM
you guys need to quit buggin tim so we can get that engine out sooner lol j/k nice job guys