The OpenGL Graphics System: A Specification

Chapter 6
State and State Requests
The state required to describe the GL machine is enumerated in section 6.2. Most
state is set through the calls described in previous chapters, and can be queried
using the calls described in section 6.1.
6.1 Querying GL State
6.1.1 Simple Queries
Much of the GL state is completely identified by symbolic constants. The values
of these state variables can be obtained using a set of Get commands. There are
four commands for obtaining simple state variables:
void GetBooleanv( enum value, boolean *data );
void GetIntegerv( enum value, int *data );
void GetFloatv( enum value, float *data );
void GetDoublev( enum value, double *data );
The commands obtain boolean, integer, floating-point, or double-precision state
variables. value is a symbolic constant indicating the state variable to return. data
is a pointer to a scalar or array of the indicated type in which to place the returned
data. In addition
boolean IsEnabled( enum value );
can be used to determine if value is currently enabled (as with Enable) or disabled.
244