stitching (hidden line removal)

Trying to highlight the edges of solid objects, I’ve drawn the objects twice, the first time with glPolygonMode(GL_FRONT_AND_BACK, GL_LINE) and the second with glPolygonMode(…, GL_FILL) and glPolygonOffset(1.0, 1.0): the edges are highlighted, but the figure is heavy to manage.
Can somebody help me?

Try looking for the cell shader on .