Apr 18, 2010

God of war 3 uses light cube

Today I found two interesting visual bugs on God Of War 3.
The screen shot above shows it uses light cube. Note the light boundary bends on leg part. It means that the light boundary is aligned to the world space not to the screen space. In other words it is not screen quad but light cube in the world space.

It also means that they are using deferred shading or light pre-pass. I don't know which one it is. I don't see much variety of materials, so it can be deferred but I don't think there can be any reasons to use deferred shading over light pre-pass these days. If I can see any sophisticated shaders such as parallax mapping, I will be able to conclude it is using light pre-pass, but I haven't seen any of them yet.

It is common to use light cube than light sphere which I am using on our project currently. I think saving the cost on fragment shader will be more efficient than saving that of vertex shader. I may be wrong, because I haven't seen any games using light sphere yet.

Another visual bug is about shadow.The first screen shot shows a badly aliased shadow on the wall. The second screen shot shows anti-aliased shadow on the character. In other words, the shadow on the wall looks jig-jagged while the same shadow looks very smooth on the character.

I am guess it is because they use different resolutions on different objects for shadow map. It makes sense to handle the shadows differently on characters from on static objects.

One more interesting thing is the aliased shadow on the wall looks still not too bad and somehow blurred. I don't know how they did it.

1 comment:

r4i 3ds card said...

Nice ideas of aliased shadow on the wall. I love your article and also love your thought what you want deffer. I wish that i will show out few photos of such light cube which will blissful for you.