Graphics Reference
In-Depth Information
Chapter 15
OpenGL ES 3.0 maintains “state information” that includes the values of
internal variables required for rendering. You'll need to compile and link
shader programs, initialize vertex arrays and attribute bindings, specify
uniform values, and probably load and bind texture—and that only
scratches the surface.
There are also a large number of values that are intrinsic to
OpenGL ES 3.0's operation. You might need to determine the
maximum size of viewport that is supported or the maximum number
of texture units, for example. All of those values can be queried by your
application.
This chapter describes the functions your applications can use to
obtain values from OpenGL ES 3.0, and the parameters that you
can query.
One of the most fundamental queries that you will need to perform
in your (well-written) applications is to obtain information about the
underlying OpenGL ES 3.0 implementation, such as which version
of OpenGL ES is supported, whose implementation it is, and which
extensions are available. These characteristics are all returned as ASCII
strings from the
glGetString
function.
