We have callbacks for that, they also do some checks and help ensure things are done
correctly. Only place where this is assumed not true is blenloader (since here we
may affect refcount of library IDs as well...).
In pipeline.c the function add_freestyle() was supposed to be called once
per frame, but after the Multi-view merge the function are called as many
as the number of views. There were however a few Freestyle parameters
that have to be initialized per frame, and initializing one of the
parameters for each view was causing double freeing of allocated memory
which was enough to result in a crash.
This calls are not strictly speaking needed for the old dependency graph, but
due to more granular nature of upcoming depsgraph more actions requires update
of relations of IDs.
On the one hand this extra tags could be wrapped with if() statements, but on
the other hand it makes sense to keep tag in sync so it's clear if some issue
is caused by missing/extra tag or by depsgraph itself.
An assertion to check if `re->clipsta` < 0 (added as part of addressing
T36009 in rBrB795034c17d76bef2a15e576ac9c70ae2268a823b) was failing when
Freestyle viewport preview rendering takes place in the camera view with
an orthographic camera (in this case, the user-defined clipping range is
used without changes, so that `re->clipsta` is positive). The
`re->clipsta` property has a negative value only when the 3D viewport is
in an orthographic view but not in the camera view. It seems that this
viewport setting cannot be identified from rendering settings accessible
from Freestyle. Now a negative `re->clipsta` value is directly checked
instead, without relying on other render flags.
The reported crash case seems to be caused by freeing compiled Python
objects in a thread. Now this issue is avoided by allocating a buffer to
store a Python script and using BPY_string_exec() to run the script. This
makes it unnecessary to repeatedly create and destroy Text data blocks.
Many thanks to Campbell Barton for his help on the bug fix.
Official Documentation:
http://www.blender.org/manual/render/workflows/multiview.html
Implemented Features
====================
Builtin Stereo Camera
* Convergence Mode
* Interocular Distance
* Convergence Distance
* Pivot Mode
Viewport
* Cameras
* Plane
* Volume
Compositor
* View Switch Node
* Image Node Multi-View OpenEXR support
Sequencer
* Image/Movie Strips 'Use Multiview'
UV/Image Editor
* Option to see Multi-View images in Stereo-3D or its individual images
* Save/Open Multi-View (OpenEXR, Stereo3D, individual views) images
I/O
* Save/Open Multi-View (OpenEXR, Stereo3D, individual views) images
Scene Render Views
* Ability to have an arbitrary number of views in the scene
Missing Bits
============
First rule of Multi-View bug report: If something is not working as it should *when Views is off* this is a severe bug, do mention this in the report.
Second rule is, if something works *when Views is off* but doesn't (or crashes) when *Views is on*, this is a important bug. Do mention this in the report.
Everything else is likely small todos, and may wait until we are sure none of the above is happening.
Apart from that there are those known issues:
* Compositor Image Node poorly working for Multi-View OpenEXR
(this was working prefectly before the 'Use Multi-View' functionality)
* Selecting camera from Multi-View when looking from camera is problematic
* Animation Playback (ctrl+F11) doesn't support stereo formats
* Wrong filepath when trying to play back animated scene
* Viewport Rendering doesn't support Multi-View
* Overscan Rendering
* Fullscreen display modes need to warn the user
* Object copy should be aware of views suffix
Acknowledgments
===============
* Francesco Siddi for the help with the original feature specs and design
* Brecht Van Lommel for the original review of the code and design early on
* Blender Foundation for the Development Fund to support the project wrap up
Final patch reviewers:
* Antony Riakiotakis (psy-fi)
* Campbell Barton (ideasman42)
* Julian Eisel (Severin)
* Sergey Sharybin (nazgul)
* Thomas Dinged (dingto)
Code contributors of the original branch in github:
* Alexey Akishin
* Gabriel Caraballo
This is a regression introduced by rBd8b00a3bf5c1 (Freestyle: memory
consumption optimization in stroke rendering).
The issue was caused by uninitialized MPoly::mat_nr values. Before the
stroke rendering optimization, individual Freestyle strokes were
represented by distinct mesh objects, and thus MPoly::mat_nr was left
unset (i.e., was always zero). Now that the stroke rendering optimization
has been done and mesh objects may represent multiple strokes of different
materials, MPoly::mat_nr had to be properly set to the material index that
refers to the material of the poly face.
This is mandatory for incoming custom normal imports from io scripts, because
often geometry here is corrupted, so we need to call mesh.validate() to clean it up.
Issue is, we cannot set custom normals before geometry is clean, so we need to store
temporary plain loop normals in a CD_NORMAL layer, validate, and then set custom normals.
So we need a way to prevent 'temp' lnors to be freed by validate.
The reported problem was due to a special case where there are no strokes
to be rendered. Since rendering an empty scene is a waste of time, the issue
was addressed here by skipping the stroke rendering process entirely.
Previously individual strokes were represented by distinct mesh objects
no matter how many vertices and materials each stroke has, although
the vertex and material counts can be quite small depending on the input
scene data. Now stroke meshes are packed into a minimum number of
mesh objects, so as to reduce the overheads of Blender object creation.
New render layer option named "View map cache" is added to reuse a
previously computed view map for subsequent rendering. The cache is
automatically updated when the mesh geometry of the input 3D scene has
been changed.
This functionality offers a major performance boost for Freestyle
animation rendering when camera-space mesh geometry is static, as well
as for repeated still renders with updates of line stylization options.
Although the "View map cache" toggle is a render layer option, the cache
memory is shared by all render layers and scenes. This means that if
Freestyle is used for two or more render layers (possibly in different
scenes through the compositor), then the cached view map for one render
layer is replaced by a new view map for another render layer and hence
no performance gain is expected.
Freestyle was using the default Cycles rendering settings (e.g., the number
of samples) and users could not change them. Now all render parameters
(except for film_transparent) are inherited for Freestyle stroke rendering.
Problem report by Danny Grimm on Facebook, thanks!
The stored context object was used for creation of shade nodes. A closer look at the
node system showed that the context is not actually used when shader nodes are
added to a shader node tree. Relying on this fact, now a NULL pointer is passed to
nodeAddStaticNode() instead of the stored bContext pointer.
Looks like the issue was caused by a UV map name starting with a lower case
letter (e.g., "color"). Capitalizing the name fixed the problem. Also adjusted
the creation of custom data layers to optimize things a bit.
Removed the previous changes for passing a line style through the Controller, and
revised the BlenderTextureShader to assign the shader node tree of a line style
(if specified) to strokes. This way the assignment of shading nodes can be done
through both the Freestyle GUI and Python scripting.
