"Unfortunately, Rage is going to be more difficult to mod," said Willits, primarily because of the complexity of the game's vaunted megatexture system, which stores the texture data for levels as one huge texture map that streams in, rather than many smaller textures.
Megatextures require huge amounts of processing power to be baked into their final form for distribution on the game disc; Willits alluded to a large number of computers working for a long time to process them, analogous to a CG render farm. . . .The megatexture issue aside, Willits said other aspects of the game will actually be easier to work with than the company's prior titles. "The description languages and the tools are a lot easier to use than the things we've done in the past," he explained.
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It also needs about 16gb free hard drive space for storing temporary images (64 4096x4096 images for diffuse and local each, then the same again for combined/lit, then the same again for "scratch" storage while generating the final compressed image).
Several members of the ETQW modding community are quite happily generating Megatextures on their home PCs. You spend more time setting them up to look nice than you do "baking" them, really.
Obviously if Rage is using higher resolution Megatextures (which seems likely) then you're probably looking at baking a mega overnight on a home PC unless it's pretty beefy.
I assume Rage has better methods for streaming it in than just based on the player's current location.
For modders, re-using a retail Megatexture is mainly just a blockout thing, since there was all sorts of stuff that was baked in (surface damage, ambient occlusion, things to "ground" structures), so obviously the detail in the mega will not match up to the detail in your map unless you really just recreate the exact size/shape of buildings and objects (or you don't care about strange dark patches on the landscape!).
I think I've posted this link before, but...
http://d8d.org/hosted/etqwmaps/ <-- overview of Megatextures in ETQW (Refinery's a good 'un!).
Tutorials for Megatexturing:
http://wiki.splashdamage.com/index.php/A_Simple_First_Megatexture
http://wiki.splashdamage.com/index.php/An_Advanced_Terrain_and_Megatexture
Once textures are baked down, that's the end of it, yeah. Most of the lighting is done in the baking pass (for ETQW anyway). If you want to change any of the textures or details you will have to at least render out a single tile (tiles are 4096x4096 textures, 8x8 grid for the whole 32k) then re-compress the Megatexture.
The savings are quite nice (4Gb of raw TGA texture data goes down to between 150-300mb) although the compression issues mean that desaturated colours tend to get a bit destroyed (usually turn a bit red/green), similar to some DXT methods really.
My only question is, how are they going to get Rage to run at 60fps on consoles and still look good? I'm not saying they can't, I'm just sorta nervous about that.
Spark