Maya's Particle Replacement aka Particle Instancing feature allows geometry to be instanced and those instances transformed using particles. More precisely, particles are replaced by arbitrary DAG nodes which maya be transforms with many shapes under them, and multiple DAG paths to those shapes.
The Instancer Iterator Class (MItInstancer) provides methods for iterating over all the dag paths to the shapes created in the scene by the replacement of particles by dag nodes.
When particles are being replaced by a shape node there will be one dag path corresponding with each particle. If, say, particles are instead being replaced by a transform with five shape nodes somewhere underneath it, then this iterator will visit five paths for every particle. Dag-instancing is also respected: if the given dag node has two child transforms each of which is a path to one shape underneath them, then this iterator will visit two paths. In other words, this iterator does not distinguish between paths resulting from a multiplicity of actual shapes and paths resulting from DAG-instances of individual shapes: all appear as different paths for the current particle.
A simple usage might look like:
Public Member Functions
|bool||isDone () const|
|MObject||instancer () const|
|MDagPath||instancerPath () const|
|MUintPtrSz||instancerId () const|
|unsigned int||particleId () const|
|unsigned int||pathId () const|
Constructs a dag-path-to-replaced-particle Iterator and resets it See reset() for more information.
Advances the iterator to the next replaced-particle dag-path in the scene. Calling reset(), then repeatedly calling this method until isDone() becomes true is equivalent to the following loop structure:
For every instancer For every particle For every dagPath connected to this instancer
Advances the iterator to the next replaced-particle in the scene, skipping over any remaining dag-paths associated with the current replaced-particle.
If there are no more particles associated with the current instancer then the iterator will advance to the next instancer in order to point at the next particle.
Returns true if the iteration is finished, i.e. there are no more dag-paths to replaced-particles in the scene.
Returns the full DAG path to the instancer that generated the current particle instance.
A NULL path will be returned if there is no current instancer being iterated
Returns the replaced-particle dag-path which the iterator is currently pointing to. Each path is to a shape. If the particle is replaced by a shape directly then there will be only one path per particle. If a particle is replaced by a transform with many child shapes then each one of those shapes will have a path. Amongst the paths corresponding to a given particle there may be multiple paths to multiple shapes. If there is no such path, a null path will be returned.
Returns the transformation matrix represented by the current path. If there is no such path, identity matrix will be returned.
Returns a unique identifier for the current instancer. Collectively, this id together with the particle id and the path id uniquely identify a "replaced particle".
|unsigned int MItInstancer::particleId||(||)||const|
Returns a unique identifier for the current particle. Collectively, this id together with the instancer id and the path id uniquely identify a "replaced particle".
|unsigned int MItInstancer::pathId||(||)||const|
Returns a unique identifier for the current path. Collectively, this id together with the instancer id and the particle id uniquely identify a "replaced particle".
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