Triangle strip

This sequence would be decoded as a set of triangles with vertices at ABC, BCD, CDE and DEF - although the exact order that the vertices are read will not be in left-to-right order as this would result in adjacent triangles facing alternating directions.

Quoting directly from the OpenGL Programming Guide: GL_TRIANGLE_STRIPDraws a series of triangles (three-sided polygons) using vertices v0, v1, v2, then v2, v1, v3 (note the order), then v2, v3, v4, and so on.

The ordering is to ensure that the triangles are all drawn with the same orientation so that the strip can correctly form part of a surface.

[5] This is significant if glEnable(GL_CULL_FACE) and glCullFace(GL_BACK) are already active (GL_BACK by default[6]), because back-facing triangles will be culled, so will not be drawn and will not appear on-screen at all.

However, if this substrip starts at an even (with 1-based counting) vertex, then the resulting triangles will change their orientation.

Optimally grouping a set of triangles into sequential strips has been proven NP-complete.

[10] Alternatively, a complete object can be described as a degenerate strip, which contains zero-area triangles that the processing software or hardware will discard.

While discontinuities in triangle strips can always be implemented by resending vertices, APIs sometimes explicitly support this feature.