Gears, UE3 and AA

Yeah It is a good looking game, but I really hope for the 360 that its best looking game will not only be semi-anti aliased grafx with overshiny textures... Halo3 can you hear me.

But besides that, Locust rocks.

 

Gears of War is one of the worst offenders I've seen for shader aliasing. Note that this is not edge aliasing, thats we've all been talking about previously. Gears probably makes the most prolific use of shaders of any title so far, on probably all surfaces, and does suffer from shader aliasing / specular noise - of the graphics this is the element that I found most distracting, and it would be more noticable on the larger TV sets / panels.

Note: expect to see more of these type undersampling artifacts in all titles this generation as shader uptake becomes more prevelant.

 

There's no fix for that is there? Short of super sampling. Or is there room for shaders to incorporate a level of filtering without being far too costly?

 

I do notice this when I am slowly looking around, but while I'm moving quickly, shooting, and generally kicking locust butt, it's not an issue.

 

Mmmmkay; the "jaggies" you see can infact be a result of bad deinterlacing of your TV-set. You're running the game with 1080i-output right?

 

No, I'm running in 720p on a 720p DLP. The first image is a framebuffer capture done by TeamXbox staff which I used to highlight the 'selective AA' being used. The second image which I took myself was not to highlight "jaggies" but to show that there is AA within the game. An unfiltered polygon edge (no AA) would not have any lighter shaded pixels running along it.

 

I think that shader-aliasing should be catered to by developers-super-sampling applied on a per-material basis(not all shaders/materials are as prone to aliasing) should be a first step solution, off the top of my head. I`m sure there are also better ways of doing this though, as someone will most certainly point-out

 

shader aliasing should be addressed on a per lighting component basis, brute shader AA is plain stupid/slow. Tipically ambient and diffuse lighting terms don't need to be 'sampled' at the same rate you might want to use for specular components.

 

A shader could be written to not compute a color for an exact point on the surface, but rather integrate over a small area around that point. Of course that's more expensive and someone would have to write and mangle the shader code. It's not exactly trivial to solve robustly, with good performance.

 

I was just thinking that yesterday. Shaders could be computed on an ordered grid for fixed surface points and interpolated for each point - basically rendering the shader as a virtual texture and filtering.

 

That doesn't solve aliasing. What you describe is no different from upscaling a low resolution to a high resolution. Upscaling actually makes aliasing worse because you're working with less sample points.

As long as you're working with sample points, the only way to get rid of aliasing is to use many of them. Straight-forward baseline rendering already gives you one sample point per pixel, so interpolation doesn't buy you anything, as there's no space to add interpolated colors in a pixel grid that is already fully accounted for.

 

that's true on the jaggies on gears...

it becomes more visible on anything bigger than a 50" HD TV...

I used to play mine regularly on a 42" samsung plasma in my room and had no problems with it

I recently upgraded to a 65" panasonic plasma (really insane sale from superbowl weekend )and it now shows some jaggies and sometimes weird texture warping/floating on some areas that wasn't aparent before.

viva pinata still looks good!

 

I don't notice the shader aliasing much in Gears, but Doom 3 had it really badly. In Gears I notice the edge aliasing mainly, but I run at non-native resolutions (on a 1080i RPCRT at 1080i and a 1200p LCD at 1280x768), so a lot of the aliasing people with true 720p screens would notice is probably being blurred through scaling.

Kinda OT, but is there ANY chance we'll see the option of pure SSAA exposed in future drivers for single card setups?

 

Strange. I haven't experienced this effect, either. I have one 360 hooked to a 42" 1080p LCD via VGA, and another hooked to a 720p projector, and in GoW the textures look fine with both display methods.