ask for help. float array transfer between maya api and mental ray geo shader

Hi, I am a newbie user of mr and maya. right now, i am writing a custom hair geo shader using lots of instances of placeholder of hair geometry. I wish to get the position, transform matrix and radius and etc from maya node wirten using api. but it seems that array data , no matter whatever methods, such kvectorarray, float with setArray true, the float or matrix array can not be filled in the mr geo shader, although it has declared the responding array float/matrix interfaces in mi file.

Later I found the mentalrayUserdata node in maya 2014. which allow arbitrary data structure to be transfered to mr shader, but it has some limitiations. the data should be encoding in hex ascii code and decoded in mr shader. And the single string cannot be bigger than 1024 byte, which means the max size of data block is 1024byte, same as 256 floats or 128 doubles. I also notice that mr 3.11 has map data shader right now. But i did not found related data node in maya. And I am also confused the use of mib_data_scalar_array and mib_data_vector_array and other shading nodes.

I am wondering how to effeciently transfer heavy data to mr from maya at the same time it can take advantage of the push-pull dirty flag node update mechnism in maya so as to produce different data set per frame. Any help and advices are appreciated. thanks a lot

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