glGetStringi

glGetStringi is a function in the OpenGL API that retrieves a string identifying a specific indexed feature or extension. It is used in conjunction with glGetIntegerv to determine the number of available extensions or parameters. The function takes two arguments: a token representing the desired string, and an index. The index is used to iterate through multiple strings that share the same token, such as a list of supported extensions.

For example, to retrieve the name of the first supported OpenGL extension, one would first call glGetIntegerv with GL_NUM_EXTENSIONS to get the total count of extensions. Then, a loop could be used, calling glGetStringi with GL_EXTENSIONS and an increasing index from 0 up to the count minus one. Each call would return a null-terminated string representing an extension name.

Similarly, glGetStringi can be used with tokens like GL_RENDERER or GL_VENDOR to retrieve specific string information about the graphics hardware and driver. The index argument is typically 0 for these queries as there is usually only one string associated with these tokens. The function returns a const GLubyte pointer to the requested string. If the index is out of bounds for the given token, or if the token is invalid, glGetStringi returns NULL. This function is crucial for runtime querying of OpenGL capabilities and hardware specifics.