[Bf-committers] Volumetrics Update

[echelon at infomail.upr.edu.cu]

Hi all!

  this weekend I've being explore render code and making tests, now
volumetrics could be dark, smoky or cloudy , previously they were only
brigther but not dark. Nex time I get conected I will upload new tests
(clouds,puffs and so).

  So the request for fire or clouds (remeber procedurals, no simulations
yet, so animation will look procedural to ,and depend on the skill of
the user) are allmost done.

 Im also made some 3D fallof function that allow for example make a box
volumetric a sphere volumetric and with some perturbation function, an
irregular sphere volumetric. This kind of stuffs will be further
developed when I move to the integration phase , I will like to reuse
functions and functionality existent in Blender , for example use a
custom curve for the 3D fallof like the new fallof for lamps.

 (I have to note that the use of fallofs will slow down renders, as
someone note in a paper and I can see it myself , but still will be
usable )

@GSR : the banding effects are minimized but still need improvements in
that area, please explain me better the adaptative aproach.

Now Im focused on shading/shadowing , the search I made in the web were in
vane, a lot of papers showing beautifull volumetrics but no shading
algorithms, or very elusive (that is a principle of modern world:
missinformation inside information), please any good paper, book,
algorithm on shading/shadowing volumetrics will help me a lot now (without
licensing issues) for exaple: I need the gradient calculation algorithm
for normals in volumetrics.
  In this part I will go a bit slow, because there's to much to implement.

 I have to note that with the arrive of volumetrics ShadeInput struct will
grow a lot, currently I have 15 new parameters and growing, because I
want the maximun user control and that will have a price, comlexitie of
options also grow, but tha's a good stuff, I dont want a simple
volumetric panel for only doing clouds. (No worries, Im not bad making
help tutorials )

shading,datasets and so will further increase the parameters number, let
me know what you think about that.

 I'll let also 2 options for calculating volumetrics:
 1-use a predefined ray deph (good for performance/planes and one sided/no
closed objects, for exaple volumetric walls, dimensional portals with
volumetric effects :)(but also have drawbacks))
 2-use the actual object deph for closed objects (thas's the part when I
look for solid recognition or a similar method or implement it myself).