# drawing outerlines for concave polygons

hi,
i rendered the filled concave polygons by tesselation.now i have to draw outerlines for those filled polygons. can any one help me for this, so that i’ll be thankful to you.
thanks and regards
k.bhogasena reddy

On Windows, check out wglUseFontOutlines. I think it uses one of the “plane sweep” algorithms to triangulate the contours.

Or maybe have a look at one of the (platform neutral) font generation/rendering libraries out there. I’ve seen several mentioned in recent threads.

Hope it helps.

Use GL_LINE_LOOP with the original Polygon Points?

I would draw the polygon twice. The first time in the normal way and the second time, using glPolygonMode (GL_LINES) and with using wider lines (I think with using glPointSize).

Hm ok whats wrong here …
> using glPolygonMode (GL_LINES)
> using glPointSize
use LineWith and this can also be a solution BUT
you also draw the triangeles inside the polygon. But if you use Z-Buffer and polygonoffset you can remove the “wrong” lines inside …