I didn't know that I can separate the two, i belive that always come together. Now I'm using a packet linear depth into a RGB 24 bit texture, but I'm not really confortable with this.
So it's possible to bound depth as target (because stencil test) and as texture (reconstruct positions) if it's read only both operations? (I mean with separate depth/stencil)
I was thinking for example with deferred decal where I perform a stencil operation to draw it on specific mesh (and dont paint others in the volume). It's possible with only one depth?
If you use a cone, two issues: cone angle, and cone length.
Regarding cone angle, I can tell you I really dislike OpenGL's point light source cone angle attentuation function because it never fades out to 0 until 180 deg. This means the actual angle you need for a bounding cone may vary all over the map depending on your tone mapping function, overlapping lights, etcetc. So I don't use it. Instead I use the D3D9 cone angle attenuation function because it is, guarenteed -- no fooling, 100% gone by the outer cone angle.
Regarding cone length, that's a bit tricky so you just have to be conservative. Thing is how far out its significant depends on tone mapping and other factors.
Battle-tested Deferred Rendering on PS3, XBox 360, and PC S.T.A.L.K.E.R.: Clear Sky Deferred Lighting and Post-processing on PS3 Parallel Graphics in Frostbite - Current & Future Rendering Tech at Black Rock Studios Crytek: Future Graphics in Games - Notes Bending the Graphics Pipeline CryEngine3: Reaching the Speed of Light Deferred Rendering Screen Space Classification for Efficient Deferred Shading
The concept is fairly simple: instead of taking a G-buffer read and lighting buffer write fill hit for EVERY light source, bin the light sources by which tile(s) of the screen they cover (tile = MxN pixel block), and render ALL of the light sources for each bin at once (i.e. read G-buffer -> +light+light+light+light+light+light -> write/blend lighting buffer). Essentially, it's just batching light sources that overlap influence regions together.