OpenGL Programming Guide: The Official Guide to Learning OpenGL, Version 4.3, Eighth Edition

Lines, Strips, and Loops

In OpenGL, the term line refers to a line segment, not the mathematician’s version that extends to infinity in both directions. Individual lines are therefore represented by pairs of vertices, one for each endpoint of the line. Lines can also be joined together to represent a connected series of line segments, and optionally closed. The closed sequence is known as a line loop, whereas the open sequence (one that is not closed) is known as a line strip. As with points, lines technically have no area, and so special rasterization rules are used to determine which pixels should be lit when a line segment is rasterized. The rule for line rasterization is known as the diamond exit rule. It is covered in some detail in the ...