The implementation is pretty straightforward.
In Cycles, sampling the shapes is currently done w.r.t. area instead of solid angle.
There is a paper on solid angle sampling for disks [1], but the described algorithm is based on
simply sampling the enclosing square and rejecting samples outside of the disk, which is not exactly
great for Cycles' RNG (we'd need to setup a LCG for the repeated sampling) and for GPU divergence.
Even worse, the algorithm is only defined for disks. For ellipses, the basic idea still works, but a
way to analytically calculate the solid angle is required. This is technically possible [2], but the
calculation is extremely complex and still requires a lookup table for the Heuman Lambda function.
Therefore, I've decided to not implement that for now, we could still look into it later on.
In Eevee, the code uses the existing ltc_evaluate_disk to implement the lighting calculations.
[1]: "Solid Angle Sampling of Disk and Cylinder Lights"
[2]: "Analytical solution for the solid angle subtended at any point by an ellipse via a point source radiation vector potential"
Reviewers: sergey, brecht, fclem
Differential Revision: https://developer.blender.org/D3171
OVERVIEW
* In 2.7 terminology, all layers and groups are now collection datablocks.
* These collections are nestable, linkable, instanceable, overrideable, ..
which opens up new ways to set up scenes and link + override data.
* Viewport/render visibility and selectability are now a part of the collection
and shared across all view layers and linkable.
* View layers define which subset of the scene collection hierarchy is excluded
for each. For many workflows one view layer can be used, these are more of an
advanced feature now.
OUTLINER
* The outliner now has a "View Layer" display mode instead of "Collections",
which can display the collections and/or objects in the view layer.
* In this display mode, collections can be excluded with the right click menu.
These will then be greyed out and their objects will be excluded.
* To view collections not linked to any scene, the "Blender File" display mode
can be used, with the new filtering option to just see Colleciton datablocks.
* The outliner right click menus for collections and objects were reorganized.
* Drag and drop still needs to be improved. Like before, dragging the icon or
text gives different results, we'll unify this later.
LINKING AND OVERRIDES
* Collections can now be linked into the scene without creating an instance,
with the link/append operator or from the collections view in the outliner.
* Collections can get static overrides with the right click menu in the outliner,
but this is rather unreliable and not clearly communicated at the moment.
* We still need to improve the make override operator to turn collection instances
into collections with overrides directly in the scene.
PERFORMANCE
* We tried to make performance not worse than before and improve it in some
cases. The main thing that's still a bit slower is multiple scenes, we have to
change the layer syncing to only updated affected scenes.
* Collections keep a list of their parent collections for faster incremental
updates in syncing and caching.
* View layer bases are now in a object -> base hash to avoid quadratic time
lookups internally and in API functions like visible_get().
VERSIONING
* Compatibility with 2.7 files should be improved due to the new visibility
controls. Of course users may not want to set up their scenes differently
now to avoid having separate layers and groups.
* Compatibility with 2.8 is mostly there, and was tested on Eevee demo and Hero
files. There's a few things which are know to be not quite compatible, like
nested layer collections inside groups.
* The versioning code for 2.8 files is quite complicated, and isolated behind
#ifdef so it can be removed at the end of the release cycle.
KNOWN ISSUES
* The G-key group operators in the 3D viewport were left mostly as is, they
need to be modified still to fit better.
* Same for the groups panel in the object properties. This needs to be updated
still, or perhaps replaced by something better.
* Collections must all have a unique name. Less restrictive namespacing is to
be done later, we'll have to see how important this is as all objects within
the collections must also have a unique name anyway.
* Full scene copy and delete scene are exactly doing the right thing yet.
Differential Revision: https://developer.blender.org/D3383https://code.blender.org/2018/05/collections-and-groups/
We handle doversion for the scene properties, but not for the
view layer overrides.
Overrides will be implemented in a different way via dynamic overrides.
For now this data is completely lost.
Patch D3205 by Kanzaki Wataru
Only implemented in Eevee for now. Collapse a closure to RGBA so we can
do NPR stuff on the resulting color.
Use an emission shader to convert the color back to a closure.
Doing this will break PBR and will kill any SSR and SSS effects the shader
the shader rely on. That said screen space refraction and ambient occlusion
are supported due to the way they are implemented.
SSR does not work with hair strands. Basically, the rays are too much
random to ever converge properly and just result in a soup of self
inter reflections.
So forcing it to not produce any SSR. Could potentially save some bandwidth
by not rendering hair to the SSR buffers.
This is a hack to properly shade wire hairs. Use stochastic sampling and
let TAA solve the noise.
At least it's way more correct than the previous hack.
This means only one texture to draw to and only one sprite per pixel.
The texture is twice as large and near and far planes are side by side.
The sprite choose the biggest coc to expand to and is redirected to the
area (layer) it belongs to.
The fragment shader discard every pixel that does not belong to the correct
layer.
Due to the scatter operation being done at half resolution, undersampling
is visible at bokeh shape edges (because of the hard cut).
This commit adds a smoothing function to minimize the problem.
Also optimize the bokeh shape parametrization by precomputing a lot of
constants.
This new blending allows background to fill the gaps left by forground
objects. However this has a drawback, background objects that should be
partially occluded in this case can be seen through the blurred objects.
This does not fix the problem of blurred foreground over sharp background.
Also cleanup code to be simpler and remove unused geometry shader.
For some we may add per object overrides, but for most we plan to keep them
strictly per viewport settings. Display settings from the mesh still need to
be moved here, only collections were done to remove that code.
This was the otherway around before. But since we can have a different size*
for cube texture now, we can compute the correct-ish texture size.
This will give us on average the same texture appearance when we will add
support for real cubemap shadows.
As much as I want to give freedom to the user, 1.5G of vram for a
single shadow is a big of a stability issue.
So limiting to 4096 for now, we may remove this limit in the future.
This mean we can now have different shadow resolutions for both.
However each shadow type keep the same size accross all lamps because of
future "real" Cube Shadowmaps limitation and to save texture sampler slots.
That said the cascade shadow resolution could (in the future) still be
changed to be adjustable per sun lamp.
It's usefull in some scenario to tweak the specular intensity of a light
without modifying the diffuse contribution.
Cycles allows it via lamps material which we currently not support in Eevee.
This is a good workaround for now.
Now they are properly converted to Linear space before interpolation.
Since the only way to get vertex color in eevee and cycles is via the
attribute node with the CD_AUTO_FROM_NAME flag, we have to know at binding
time which type of buffer will be connected to this auto input.
We store this information inside the batch cache (together with the according
uniform name) and pass it as uniform to the shader which does conversion if
needed. The same shader can then be reused to draw another mesh with
different auto layers configuration.
Because:
- Less redundancy.
- Better suffixes.
Also a few modification to GPU_texture_create_* to simplify the API:
- make the format explicit to the texture creation process.
- remove the component count as it's specified in the GPUTextureFormat.
