Blender Git Loki

A bit shorter internal names for bparticles structs and functions.

Added particles sequence in state bpy api.

Added 'attributes' sequence property in the state type.

Custom get/set methods for the "Particle" type. This supports particle
attributes directly as python properties in the particle wrapper type.
If a particle identifier has no corresponding data in the state yet it
will be automatically created when writing.

Added "name" property (read-only) for attribute states.

Added new python module 'bparticles' for implementing a full python API
to define particle states. This is necessary because otherwise the RNA
can only refer to data that already exists in the DNA library (bpy.data)
but not create temporary structs. The state should be defined separately
before replacing a particle system's state with it. This is similar to
how bmesh works.

Basic submodule 'types' in bparticles, defining a PyObject type for
the particle state.

Added python type for particle attribute state in the bparticles module.

Flags for particle attributes:

- REQUIRED: These attributes are always existent in every particle
system. Currently this is only the "id" layer, position might also
be added
- PROTECTED: Attribute name, datatype, etc. can not be changed. Only
user-defined attributes can be modified this way.

Clear the attribute buffers when adding new particles to a state. This
should probably use a specific default value for each attribute at some
point.

Initialize the "id" attribute when adding particles to the state.

RNA fix: using RNA_def_struct_sdna_from works only with actual pointers,
but not with directly nested structs (NParticleAttributeDescription in
this case). Resort to including "desc." prefix in the property paths.

Use a readonly flag for attributes and a second variant of the Data
RNA access types to prevent writing over immutable attributes ("id" in
particular).

Add position attribute to particles by default.

Basic display feature for particles. This is organized as a list of
NParticleDisplay in the modifier for now. Each NParticleDisplay adds
a visualization element of some type in the viewport, which will allow
combining elements for custom attributes with standard display modes
for particles.

Use the new attribute flags to determine editability in RNA.

Added missing read/write code for particle display.

Alternative particle iterator init method using a specific particle ID.

Store the particle state in iterators instead of the particle system.

Yet another restructuring effort: Separate the state from the particle
system settings. Attributes can be accessed by name in the state data,
for now this uses plain linear search in a NULL-terminated array, but
can eventually use a hash table for O(1) lookup.