A mesh can consist out of multiple material. Take a character with clothing's. the skin can be a different material as the different clothing's. During compositing it is a common use-case to only do a part of the composit on only a specific material. Currently this can not be done.
In blender movies this feature is known to be implemented, but until now it never got integrated into trunk.
Proposal
With material index the Blender internal renderer will be capable of creating a buffer containing the material indexes of the first pixel-hit. This will be implemented in the same manner as the object index.
In the compositor the ID Mask node can be used to extract the information out of the Render pass.
Impact
User interface
On the properties-space the next changes will be done
Scene⇒Render layer⇒Passes⇒Material index will be added
Material⇒Options⇒Pass index will be added
DNA
Material struct will get an new field called “index”. this will be a short-type.
Material struct the field pad will be removed.
A new Render-layer pass will be added (bit 1«18)
RNA
Material RNA is updated (based on “pass index” from object)
Render layer RNA is updated (based on IndexOB)
Blender internal renderer
The Blender internal renderer will process the render pass as a copy of the Object index.
Blender compositor
The render layer input will get a new output socket called “IndexMA”
Usage
An example on how to use material index can be found at:
https://svn.blender.org/svnroot/bf-blender/trunk/lib/tests/compositing/composite_materialindex.blend
This is also example of a commit message longer than the commit itself :)
- fix mistake with grease pencil UI (&& was intended but & used).
- use (void) rather then () across _all_ blenders code.
- a few minor edits, don't shadow stack variables in roll calculation & avoid running memset() for VBO vertex map.
This was reverted by Brecht r22541 because its inefficient but there is no way to work around this with povray at the moment so adding it back as optional args.
- user input gets non utf8 chars stripped all text input other then file paths.
- python has the same limitations, it will raise an error on non utf8 strings except for paths use unicode escape literals so its possible to deal with saving to these file paths from python.
- new string functions
BLI_utf8_invalid_byte(str, len) returns the first invalid utf8 byte or -1 on on success.
BLI_utf8_invalid_strip(str, len) strips non utf-8 chars.
if compositing, sequencer, fields, etc should be rendered, or if the
render does that itself. The weak point is that this only applies to
rendering, so if you open the compositor, it will still run on the
rendered result. Enabled by default, set to False to disable.
Ambient occlusion: multiplied with direct lighting by default, add
is also still available and more blending methods might be added if
they are useful. This is fundamentally a non physical effect.
Environment lighting: always added as you would expect (though you can
subtract by specifying negative energy). This can be just white or take
colors or textures from the world.
Indirect lighting: only supported for AAO at the moment (and is still
too approximate), and also is always added. A factor is available to
specify how much is added, though value 1.0 is correct.
Also:
* Material ambient value now defaults to 1.0.
* Added Environment, Indirect and Emit pass.
* "Both" blending method is no longer available.
* Attenuation, sampling parameters are still shared, some could be split
up, though if they are different this would affect performance.
for panels it would fail silently but for menu's it meant further references would give errors.
increase the registered class name from 32 to 64 and raise an error if the limit reached.
eg.
scene.objects.link()
object.constraints.new()
mesh.verts.transform(...)
mesh.faces.active
PropertyRNA stores an StructRNA pointer where these can be defined.
* Disable setting array length of dynamic array for now, this was not
implemented correct, and it's not really needed now.
* Allow all dimensions to be dynamic size, not just the first.
* Change storage of multidimensional to be simpler.
* Rename API functions to be more compact.
* Fix some bugs in the implementation.
* RenderLayer.rect and RenderPass.rect use a multidimensional
dynamic array now.
possible from python, but it's still work in progress.
Pointers and collections are restricted to types derived from
IDPropertyGroup (same as for operators), because RNA knows how to
allocate/deallocate those.
Collections have .add() and .remove(number) functions that can be
used. The remove function should be fixed to take an other argument
than a number.
With the IDPropertyGroup restriction, pointers are more like nested
structs. They don't have add(), remove() yet, not sure where to put
them. Currently the pointer / nested struct is automatically allocated
in the get() function, this needs to be fixed, rule is that RNA get()
will not change any data for thread safety.
Also, it is only possible to add properties to structs after they have
been registered, which needs to be improved as well.
Example code:
http://www.pasteall.org/7201/python
* Add RenderResult.load_from_file to load whole multilayer exr's at once.
* Removed x/y offset from RenderLayer.load_from_file, better to encourage
using offset in begin_result() to minimize memory usage.
* Added WITH_OPENEXR in some screen/file/image module for scons/make, exr
was not working in some places there.
- use RNA_struct_blender_type_set to set the type to NULL before its freed
There is a memory error here when reloading scripts - ui_handler_panel_region, need to look into theis further.
lay = result.layers[0]
lay.rect_from_file("somefile.png", part.x, part.y)
If the source image is bigger then the render layer x/y offsets can be used to choose the part of the image use.
An engine to use for output can now be selected an influences what
shows in the buttons window, only showing relevant data. The idea
behind this is to make it more clear what is supported where, make
the system more pluggable for external render/game engines, and save
space hiding stuff that is not relevant anyway.
* Top header now has an engine menu, to choose between the blender
render engine, game engine, and other future external engines.
* If the game engine is enabled, the buttons window should show
only properties that work in the game engine, and similarly for
the render engine.
* Moved panels from the logic space and game tabs to the physics,
scene and world tabs instead, and removed the game tab.
* Materials and textures tabs should eventually become game
specific too, to better show what is supported.
This adds a RenderEngine type to RNA, which can be subclassed
in python (c++ will follow once we support subclassing there).
It's very basic, but plugs into the pipeline nicely. Two example
scripts:
http://www.pasteall.org/6635/pythonhttp://www.pasteall.org/6636/python
Issues:
* Render runs in a separate thread, and there is unrestricted
access, so it's possible to crash blender with unsafe access.
* Save buffers and full sample are not supported yet.
