- Method glArrayElement
glArrayElement commands are used within glBegin/glEnd pairs to specify vertex and attribute data for point, line, and polygon primitives. If GL_VERTEX_ARRAY is enabled when glArrayElement is called, a single vertex is drawn, using vertex and attribute data taken from location i of the enabled arrays. If GL_VERTEX_ARRAY is not enabled, no drawing occurs but the attributes corresponding to the enabled arrays are modified.
Use glArrayElement to construct primitives by indexing vertex data, rather than by streaming through arrays of data in first-to-last order. Because each call specifies only a single vertex, it is possible to explicitly specify per-primitive attributes such as a single normal per individual triangle.
Changes made to array data between the execution of glBegin and the corresponding execution of glEnd may affect calls to glArrayElement that are made within the same glBegin/glEnd period in non-sequential ways. That is, a call to
glArrayElement that precedes a change to array data may access the changed data, and a call that follows a change to array data may access original data.
Specifies an index into the enabled vertex data arrays.