Just Cause 2 lighting model?

malcolm

Anyone here work at Avalanche, or anyone know what the light rig is for Just Cause 2. I'm seeing all this indirect lighting in the game and I'd really like to know how they are getting it? I'm assuming the world is way to big to bake lightmaps on and I don't see any dxt artifacting in the lighting. At first I thought it was a vertex occlusion bake but there is colour in the indirect lighting which I just can't figure out. Are they doing some fancy pants spherical harmonic, or are they using the crysis one bounce from the sun thing?

Ark

Well on the PC version, it as SSAO for simulating indirect illumination, don't know if its practical on the console versions.

Doesn't the game have a full day/night cycle? Cant see there being any lightmaps used in conjunction with that.

Direct lighting is probably like you say, one direct light to simulate the sun/moon that cast shadows. They probably use deferred lighting as well which gives them the option to use a lot more bounce/fill lights.

Mostly assumptions, but thats my take.

CrazyButcher

https://mpi-inf.mpg.de/~ritschel/SSDO/

Eric Chadwick

Cool paper CB!

Tumerboy

Nice! I sent that off to our graphics programmer :P

malcolm

Ark there is no screen space ao in the console version of Just Cause 2, but they definitely have some kind of trick or indirect lighting in the shadows. I'd really like to know what it is.

Crazybutcher I've seen that paper before quite some time ago, they are definately not doing this in Just Cause 2 since that stuff is all screen space.

Brice Vandemoortele

how can you tell it's not a screen space effect?

CrazyButcher

given the size of their world, anything non-screen space would be hard to pull off efficiently.
also humus (graphics coder there) states on his blog several issues you have to think of when doing ssao on xbox due to the edram framebuffer.

Brice Vandemoortele

i don't really get it
screen space has the inherent benefit of being independent from the complexity of the scene, and there's already some xbox360 ssao implementations out there.

also Could you post a url for that blog?

Eric Chadwick

Humus

Peris

they definitely have no ssao on the console version. I think it's just spherical harmonics, and on large assets like buildings they bake in ao on a second uv channel. From what I can tell, there wasn't really any light bouncing being simulated.

Brice Vandemoortele

awesome resource eric, I have stuff to read for the next decade !

CrazyButcher

the latest shaderx (now gpu pro) book has a chapter on just cause rendering tech. once the book is available, we should know for sure. that said maybe they have dropped the effects for console indeed, given the hw limitations... never saw the game on a console.

http://gpupro.blogspot.com/

after further reading there, it looks like they indeed don't use SSAO but occlusion volumes

Ambient occlusion volumes - Our solution to ambient occlusion from dynamic objects.

Now I actually recall pictures of that effect in some publication I saw lately, just don't remember the exact name.

http://research.nvidia.com/publication/ambient-occlusion-volumes
but thats not the one I meant, I guess there was a gdc presentation on just cause as well

... or not, but anyway somewhere I have seen that image of a soldier standing next to a wall and the skeleton had occlusion volumes linked to it (squashed spheres and capsules I think) that would approximate the ao volume

but I dont think I have seen it mentioned here
http://developer.amd.com/documentation/presentations/Pages/default.aspx
or here
http://developer.nvidia.com/object/gdc-2010.html

malcolm

CrazyButcher nice find on the whitepaper stuff. Totally interested in their lighting and alpha blending.

Brice Vandemoortele the easiest way to tell something's not in screen space is move the camera around and if the effect's not changing each frame it's not screen space. That and when you move the character in front of something there is a halo of no ssao around them.

Ark

Well, they've either labeled it wrong in the options or the PC version differs.

CrazyButcher

hm thats interesting indeed... well I guess easiest is asking humus. I never played the game at all, nor have the demo.

malcolm

Yes I read about that, the pc version does use SSAO as an option but the console version does not have it. I'm not really interested in how they do ao but how they are getting different coloured ambient lighting inside a shadow, ao would just change the value of the shadow colour but I'm seeing actual hue differences which is quite impressive to me, unless it's a baked lightmap then it's the same system we're using.

Eric Chadwick

Maybe ambient cubes like Half-Life 2. Got any shots?

SHEPEIRO

i dont think its anywhere near as complicated as ambient cubes or sperical harmonics... the bounce light (always coming from the ground) looks to be the same colour independant of what ground the objects on and how high etc... its probably a single set value continuous up directional light... edit at most it may use a version of the terrain map (if they use texture masks to alter the colour dependant on position etc....

cheap smokes and spangly mirrors used to good effect...from what i can tell...of course could be wrong