iD Tech 5 and MegaTextures...

[savage]

At the recent E3 event, John Carmack showed off his new engine called iD Tech 5, which will be used in an upcoming title called Rage (http://www.gametrailers.com/game/5315.html). He spoke extensively about a thing called a MegaTexture and hot it would free artist because they could use unlimited amount of textures without it affecting performance. It sounds very intriguing, but I could not find any indepth technical information on the internet about or even musings on how it might work. Does anyone here know about MegaTextures? Can you point me to some resources?

If you have not seen the John talk about Tech 5 yet, then have a look @
http://www.gametrailers.com/game/4440.html

Not that I'm likely to use it in any game soon, but it's always good to know.

[www.sibvrv.com]

MegaTextures not posible only on Mac... :( we have max 8192x8192... :lol:

[NecroDOME]

It not about the textures size, but about how you render it. I think its done by making textures procedural and render them over the terrain (with cubes or so). So its not that it stores textures like 1000000x1000000 in the memory.

EDIT:
OK, by watching the movie he also said that is all generated from a "base texture"

[Robert Kosek]

Yeah, so it has a base texture, and then all the decals are "baked" on. Or, I guess when you're in range the textures bake for you so filesize is a bit down. I dunno. :lol:

I'm impressed and I wonder how they did it seamlessly.

[savage]

MegaTextures not posible only on Mac... :(

Hi Roman,
I'm not sure what you mean here. Could you please clarify.

[Robert Kosek]

He means that mega textures aren't supported on Macs, that they're capped at 8192x8192 dimensions. Unless I misunderstood. :P

[www.sibvrv.com]

Mega Textures supported only on Mac's. on our PC's we have hardware limits like 8192x8192 per texture.

[savage]

I've been trying to think how I would implement something like that, and my guess is that it works the same way player type models are skinned, but extending it to the whole game area/level. You have your model and you have an associated texture, at design time you can layer as many textures as you like. I think this would all be stored in an xml type file at design time ( this is also so that it can support undo/redo as well as position, alpha etc ). Then when generating the "skin" for the level, it merges/blends all the textures from the information within the xml file and creates one ginormous texture which the level will be skinned with and this can include "Real Relief" type information to make the rocks and the like look fantastic. So this acts like a uber detailed base texture. Then on top of that you render your buildings and other movable objects like characters/blades of grass/trees that move in the wind. IIRC the level he showed off does not include blades of grass that move only cars racing around the track. things like animated models etc would affect the overall performance, which I don't think is what he is referring do.

I think it's mentioned somewhere that this MegaTextures are streamed during gameplay which is how he gets around the fact that you can't load a 100,000 x 100,000 texture into GPU memory.

I've just found out that there is a thread about it over on gamedev (http://www.gamedev.net/community/forums/topic.asp?whichpage=1&pagesize=25&topic_id=460053), so I'm off to read it.