OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Debug Messages

Each message generated by OpenGL is comprised of a text string and a number of attributes. These are passed back to the application in the parameters to the callback function. The prototype of the callback function is shown in Example H.3 and a declaration of the function is shown below.

void callback(GLenum source, GLenum type, GLuint id,                         GLenum severity, GLsizei length,                         const GLchar* message, void* userParam);

This is a callback function that will be called by OpenGL when it needs to send the application a debug message. source, type, id, and severity indicate the source, type, id, and severity of the message, respectively. length contains the length of the string whose address ...