[erlang-questions] How to implement the A Star find path algorithm using NIF?

[skyman]

Hi Dmitry,

Thanks for your reply.
The map of our game is large(1000 * 1000 grids). If I use NIF to implement the A Star find path in C, can I allocate the map grid array(1000 * 1000) in C, and when map blocks changed, Erlang calls 'updateBlock' NIF to update the grid state in grid array in C?


Thanks!





At 2017-07-11 00:33:34, "Dmitry Kolesnikov" <dmkolesnikov@REDACTED> wrote:

Hello,


On 10 Jul 2017, at 19.11, skyman <cloudzen@REDACTED> wrote:


Hi everybody,


Our game is using A Star algorithm to find path. For performance I want to write it in C language, and Erlang calls it by NIF. I don't know whether the map data is maintained in C or in Erlang. Can anyone tell me?



Map is native data structure. However, you need to use enif interface to interact with it. 
http://erlang.org/doc/man/erl_nif.html#enif_get_map_value


In addition, is there any better solution than NIF?



I’ve used to solve a “routing” issues on pure Erlang using ETS, lists, etc. However, this mainly depends on your traffic, latency and size of routing tables. It is hard to give a straight forward answer not knowing this figures.      






Thanks very much!


Best Regards, 
Dmitry
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