function addTriangle(lines, index, i0, i1, i2) {
  lines[index++] = i0;
  lines[index++] = i1;

  lines[index++] = i1;
  lines[index++] = i2;

  lines[index++] = i2;
  lines[index] = i0;
}
Content pipeline functions for geometries.

@namespace GeometryPipeline

@see Geometry