void glGetShaderInfoLog(GLuint shader, GLsizei maxLength, GLsizei *length, GLchar *infoLog)
glGetShaderInfoLog returns the information log for the specified shader object. The information log for a shader object is modified when the shader is compiled. The string that is returned is null terminated.
glGetShaderInfoLog returns in infoLog as much of the information log as it can, up to a maximum of maxLength characters. The number of characters actually returned, excluding the null termination character, is specified by length. If the length of the returned string is not required, a value of NULL can be passed in the length argument. The size of the buffer required to store the returned information log can be obtained by calling glGetShader with the value GL_INFO_LOG_LENGTH.
The information log for a shader object is a string that may contain diagnostic messages, warning messages, and other information about the last compile operation. When a shader object is created, its information log is a string of length 0.
glGetShaderInfoLog is available only if the GL version is 2.0 or greater.
The information log for a shader object is the OpenGL implementor's primary mechanism for conveying information about the compilation process. Therefore, the information log can be helpful to application developers during the development process, even when compilation is successful. Application developers should not expect different OpenGL implementations to produce identical information logs.
GL_INVALID_VALUE is generated if shader is not a value generated by OpenGL.
GL_INVALID_OPERATION is generated if shader is not a shader object.
GL_INVALID_VALUE is generated if maxLength is less than 0.
GL_INVALID_OPERATION is generated if glGetShaderInfoLog is executed between the execution of glBegin and the corresponding execution of glEnd.
glGetShader with argument GL_INFO_LOG_LENGTH
glCompileShader, glGetProgramInfoLog, glLinkProgram, glValidateProgram