glMap1 and glMap2 define evaluators. glGetMap returns evaluator parameters. target chooses a map, query selects a specific parameter, and v points to storage where the values will be returned.The acceptable values for the target parameter are described in the glMap1 and glMap2 reference pages.
query can assume the following values:
GL_COEFF
v returns the control points for the evaluator function. One-dimensional evaluators return $order$ control points, and two-dimensional evaluators return $uorder ~times~ vorder$ control points. Each control point consists of one, two, three, or four integer, single-precision floating-point, or double-precision floating-point values, depending on the type of the evaluator. The GL returns two-dimensional control points in row-major order, incrementing the $uorder$ index quickly and the $vorder$ index after each row. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.
GL_ORDER
v returns the order of the evaluator function. One-dimensional evaluators return a single value, $order$. The initial value is 1. Two-dimensional evaluators return two values, $uorder$ and $vorder$. The initial value is 1,1.
GL_DOMAIN
v returns the linear $u$ and $v$ mapping parameters. One-dimensional evaluators return two values, $u1$ and $u2$, as specified by glMap1. Two-dimensional evaluators return four values ($u1$, $u2$, $v1$, and $v2$) as specified by glMap2. Integer values, when requested, are computed by rounding the internal floating-point values to the nearest integer values.