State Queries - Praise for OpenGL ES 30 Programming Guide - page 423

Querying Implementation-Dependent Limits

Many rendering parameters depend on the underlying capabilities of
the OpenGL ES implementation—for example, how many texture units
are available to a shader, or what the maximum size for a texture map
or aliased point is. Values of those types are queried using one of the
functions shown here:

void glGetBooleanv (GLenum pname , GLboolean * params )

void glGetFloatv (GLenum pname , GLfloat * params )

void glGetIntegerv (GLenum pname , GLint * params )

void glGetInteger64v (GLenum pname , GLint64 * params )

specifies the implementation-specific parameter to be queried
specifies an array of values of the respective type with
enough entries to hold the return values for the associated
parameter

pname
params

A number of implementation-dependent parameters can be queried, as
listed in Table 15-1.

Table 15-1 Implementation-Dependent State Queries

Minimum/
Initial
Value State Variable Description Get Function

GL_MAX_ELEMENT_
INDEX

glGetInteger64v

Maximum element index 2 24 - 1

GL_SUBPIXEL_
BITS

Number of subpixel bits
supported

4

glGetIntegerv

GL_MAX_TEXTURE_
SIZE

Maximum size of a
texture

2048

glGetIntegerv

GL_MAX_3D_
TEXTURE_SIZE

Maximum size of 3D
texture supported

256

glGetIntegerv

GL_MAX_ARRAY_
TEXTURE_LAYERS

glGetIntegerv Maximum number of

texture layers supported

256

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