It occurred to me yesterday that there seems to be a major misunderstanding in
the way Atmospheric Light Scattering (ALS) is perceived by different people. So
in order to avoid future misunderstandings, let me try to clarify my side once
again.
Vivian:
> Do we need to go down this road? We are breaking more and
> more for minimal gains. Did we ever restore the wake effect on the Carrier
> with Atmospheric Light Scattering?
Emilian (a while ago):
> I have nothing about the core of the Advanced weather engine, I have an issue
> of how you interact with it, and how it interacts with other parts of the
> whole system... and in my view this is broken.
> I also have nothing against the idea of the atmospheric scattering, I have an
> issue with how it's done, which is suboptimal in my view... and again of how
> you can interact with it/ how it affects other systems, and how it's affected
> by
> other systems.
The common theme here is the perception that something is broken, which is
naturally not my perception. For instance, the fact that ALS doesn't have a
wake shader effect indicates its brokenness the same way as the fact that the
default rendering doesn't have procedural texturing working - which is to say,
not at all.
Vivian might correct me, but I think I finally understand where that notion
comes from. I think it comes from the view that ALS is in essence just another
way to compute fog and light for what the default rendering scheme does, and
from this perspective, any effect that doesn't work is indeed broken.
The original plan was indeed to implement things as just different fog and
light, there is still the parameter 'fog-type' in the effects which would
support such an implementation, and there was a 6 months window during which
Emilian and Vivian had the opportunity to implement it that way. As this didn't
happen (for whatever reason) I decided to ask for some help and Fred kindly
told me how to implement it as a different rendering framework (i.e. loading a
whole different effect rather than a different fog shader only).
So, from where I stand, that decision is done and it is now a different
rendering framework, which means clean slate, all effects have to be written
from scratch, with all the pros and cons to that (which we might debate
endlessly). So since this window of opportunity to start from scratch happened,
I took the opportunity to address a few things I saw as shortcomings in the
default rendering framework we had. Just to give a few examples:
* Environment interfacing:
Emilian's view that the way ALS and Advanced Weather interact with the rest is
broken is... bold. Just to give an example for how he addressed the interface,
for instance the water shader needs to know the amount of reflected light at
the water surface in order to compute reflection.
Emilian's and Vivian's version of the water sine shader solves this by passing
the cloud layer configuration settings of Basic Weather to the shader and then
compute in the fragment shader from that the amount of light. This means that
a) Advanced Weather has no chance (even conceptually) of ever passing the
correct information to the shader since it doesn't use the Basic Weather config
properties to create clouds and my understanding is that it is even impossible
to write these properties without actually generating visible clouds
interfering with what Advanced Weather does, and that b) a quantity which
changes in Basic Weather once a few minutes (when a new METAR comes in) is
computed about 60 million times each second. I may not be a rendering wizard,
but this doesn't sound like the way to implement an environment interface to
me.
My supposedly broken interface references a single property 'light reaching the
ground' for the same purpose. That property isn't native to the weather
system, it can be set by hand with the browser without affecting anything else
but the shader or be computed by any weather system currently running, i.e.
shader control parameters are explicitly and always separated from native
weather system parameters. This means the computation can be done if and only
if needed, and the interface doesn't prefer one weather system over the other.
* Consistency
I've witnessed quite a few forum discussions with people complaining that they
didn't think selecting higher quality shader settings would give them higher
quality visuals (usually this was about the crop and forest overlay texture
effects which some like and some don't - I have my opinion which is irrelevant
here). Likewise, snow and fog were not always consistent across landclasses (I
believe this is fixed now).
Starting from scratch offered the opportunity to organize quality settings with
a clear idea in mind, using a consistently selected set of effects. Now,
consistent doesn't necessarily mean superior, it just says it's all my idea of
visual quality, not a mixture of different ideas. B
