Blender Git Loki

Fix compiler warnings from own recent rB0d5c7e5e36b9.

Fix (unreported) bad copying of Ocean modifier.

Was needlessly complicated code, forgot to copy a value (foam_fade), and
was utterly leaking memory!

Depsgraph: Synchronize selection from original scene to copied-on-write one

This makes it possible to select objects in the viewport.

Selection in edit mode is still tricky, mainly because currently such update
would require tagging batch as updated, which is not possible with using just
and original object because it will never have batch.

Possible solution here would be to introduce some "batch" or "render" component
to depsgraph ID node for objects, so we can tag batch for update via depsgraph
tagging API.

Depsgraph: Initial groundwork for copy-on-write support

< Dependency graph Copy-on-Write >
--------------------------------
^__^
(oo)_______
(__) )/
||----w |
|| ||

This is an initial commit of Copy-on-write support added to dependency graph.
Main priority for now: get playback (Alt-A) and all operators (selection,
transform etc) to work with the new concept of clear separation between
evaluated data coming from dependency graph and original data coming from
.blend file (and stored in bmain).

= How does this work? =

The idea is to support Copy-on-Write on the ID level. This means, we duplicate
the whole ID before we cann it's evaluaiton function. This is currently done
in the following way:

- At the depsgraph construction time we create "shallow" copy of the ID
datablock, just so we know it's pointer in memory and can use for function
bindings.

- At the evaluaiton time, the copy of ID get's "expanded" (needs a better
name internally, so it does not conflict with expanding datablocks during
library linking), which means the content of the datablock is being
copied over and all IDs are getting remapped to the copied ones.

Currently we do the whole copy, in the future we will support some tricks
here to prevent duplicating geometry arrays (verts, edges, loops, faces
and polys) when we don't need that.

- Evaluation functions are operating on copied datablocks and never touching
original datablock.

- There are some cases when we need to know non-ID pointers for function
bindings. This mainly applies to scene collections and armatures. The
idea of dealing with this is to "expand" copy-on-write datablock at
the dependency graph build time. This might introduce some slowdown to the
dependency graph construction time, but allows us to have minimal changes
in the code and avoid any hash look-up from evaluation function (one of
the ideas to avoid using pointers as function bindings is to pass name
of layer or a bone to the evaluation function and look up actual data based
on that name).

Currently there is a special function in depsgraph which does such a
synchronization, in the future we might want to make it more generic.

At some point we need to synchronize copy-on-write version of datablock with
the original version. This happens, i.e., when we change active object or
change selection. We don't want any actual evaluation of update flush happening
for such thins, so now we have a special update tag:

DEG_id_tag_update((id, DEG_TAG_COPY_ON_WRITE)

- For the render engines we now have special call for the dependency graph to
give evaluated datablock for the given original one. This isn't fully ideal
but allows to have Cycles viewport render.

This is definitely a subject for further investigation / improvement.

This call will tag copy-on-write component tagged for update without causing
updates to be flushed to any other objects, causing chain reaction of updates.
This tag is handy when selection in the scene changes.

This basically summarizes ideas underneath this commit. The code should be
reasonably documented.

Here is a demo of dependency graph with all copy-on-write stuff in it:

https://developer.blender.org/F635468

= What to expect to (not) work? =

- Only meshes are properly-ish aware of copy-on-write currently, Non-mesh
geometry will probably crash or will not work at all.

- Armatures will need similar depsgraph built-time expansion of the copied
datablock.

- There are some extra tags / relations added, to keep things demo-able but
which are slowing things down for evaluation.

- Edit mode works for until click selection is used (due to the selection
code using EditDerivedMesh created ad-hoc).

- Lots of tools will lack tagging synchronization of copied datablock for
sync with original ID.

= How to move forward? =

There is some tedious work related on going over all the tools, checking
whether they need to work with original or final evaluated object and make
the required changes.

Additionally, there need synchronization tag done in fair amount of tools
and operators as well. For example, currently it's not possible to change
render engine without re-opening the file or forcing dependency graph for
re-build via python console.

There is also now some thoughts required about copying evaluated properties
between objects or from collection to a new object. Perhaps easiest way
would be to move base flag flush to Object ID node and tag new objects for
update instead of doing manual copy.

here is some WIP patch which moves such evaluaiton / flush:

https://developer.blender.org/F635479

Lots of TODOs in the code, with possible optimization.

= How to test? =

This is a feature under heavy development, so obviously it is disabled by
default. The only reason it goes to 2.8 branch is to avoid possible merge
hell.

In order to enable this feature use WITH_DEPSGRAPH_COPY_ON_WRITE CMake
configuration option.

Fix (unreported) bad copying code in Mesh Deform modifier.

Fix (unreported) Dynamic Paint modifier not increasing ID usercount in copy function.

*Sigh* One more example of why we should keep ID management handling in
as few places as possible! It's impossible to keep more than a few
places in sync regarding which ID pointer is refcounted etc.

Fix (unreported) memory leak in Fluid modifier copying.

Also generally simplify/sanitize this copy code.

Gawain API naming refactor

Use consistent prefix for gawain API names as well as
some abbreviations to avoid over-long names, see: D2678

Cleanup: quiet warnings

CMake: Remove unused legacy depsgraph option

We don't have legacy depsgraph anymore, no reason to keep the option.

Manipulator: use ui-scale for widgets

Eevee: Add data display for planar reflection.

Maybe not very useful but it's here for feature parity with the other probes.
The fragment shader clipping is here because I'm lazy and don't want to creating a proper quad Batch.

Eevee: Fix Planar Probe offset changing influence calculation.

Planar Probe: Add UI, 3d view Display and change defaults.

Eevee: Initial implementation of planar reflections.

Still pretty barebone: No roughness support, No normal distortion support.

Eevee: Add special shader for depth prespass.

This way we can extend it to output more data (like motion vectors).
Add a variation that uses clip distances.

DrwManager: Remove the need for buffers to be available.

This way we can just avoid binding a texture by setting it's ref to NULL.

DrwManager: Remove unnecessary ifs.

Probe: Add planar type.

DrwManager: Add support for Custom Clipping Planes