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

Additional Tessellation Evaluation Shader layout Options

Finally, should you want to output points, as compared to isolines or filled regions, you can supply the point_mode option, which will render a single point for each vertex processed by the tessellation evaluation shader.

The order of options within the layout directive is not important. As an example, the following layout directive will request primitives generated on a triangular domain using equal spacing, counterclockwise-oriented triangles, but only rendering points, as compared to connected primitives.

layout (triangles, equal_spacing, ccw, points) out;