# HoloPlayCore.h This header contains declarations for functions in the HoloPlayCore dynamic library, which handles communication with the [HoloPlay Service](https://lookingglassfactory.com/software/holoplay-service) runtime. A programmer looking to design a custom renderer for Looking Glass devices ought only to need the functions declared in this header file. They have simple arguments and return types, and are designed to be easily bound from any programming language and dropped into custom rendering pipelines. Nearly all of them map directly to combinations of functions declared in [libHoloPlayCore.h](/legacy/legacy-software/core-sdk/index-1/libholoplaycore.md); they are provided for developer convenience and simple cross-language binding of functions that might return structs or opaque object pointers. For insight on how these work under the hood and more direct access to the data they provide, see that page. * [State Functions](/legacy/legacy-software/core-sdk/index-1/index/state-functions.md) - used to manage the lifecycle of the HoloPlay Core Application * [General Query Functions](/legacy/legacy-software/core-sdk/index-1/index/general-query-functions.md) - helper functions to query information from the state message. * [Device Query Functions](/legacy/legacy-software/core-sdk/index-1/index/device-query-functions.md) - query per-device configuration parameters. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://lfdocs.lookingglassfactory.com/legacy/legacy-software/core-sdk/index-1/index.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.