How does glPolygonMode work?glPolygonMode
can change the way polygons (triangles) are rasterised. One can render the triangles as points,
lines, or filled.
Syntax is
void glPolygonMode(Glenum face,
Glenum mode);- face can be GL_FRONT, GL_BACK, or
GL_FRONT_AND_BACK
- mode can
be GL_POINT,
GL_LINE, or GL_FILL

glPolygonMode
is a state variable (once set, it affects everything that follows)