create triangle_strip of given polygon

I have a given polygon that looks like this …

     /  \
  /|      |\
 / |      | \
|  |      |  |
|  |      |  |
 \ |      | /
    \    /
     \  /

does anyone know a simple method to obtain the vertex order that generates a GL_TRIANGLE_STRIP
out of this poly…

I tried it with pen and paper but ended up with one triangle left (and trying all possibilites is nothing I want to go for)

tnx in advance

what about GL_TRIANGLE_FAN, starting at one of the four corners of the rectangle (assuming the polygon is flat)?

sorry I forgot to mention that it is not flat the middle quad is the bottom and the rest is closed together to form a roof-like structure.

Until now I have used an indexed vertex list but a triangle strip would increase performs alot.