Polygonal vertices convexo-concave determining is one of the fundamental issues in Computer Graphics. In this paper

plane space is separated into 2 region defined as positive region and negative region based on the direction and the stretched of the line segment. Accordingly transform identification of convexity or concavity of the next vertices into identification of the region position. Consequently the operation of multiplication can be averted. In order to do the best in practical determining

3 areas is separated of the plane space

whereas not the same as earlier. These area are based on two horizontal lines

two vertical lines and two 45°diagonal lines through the vertices of the line segment. Because the partition is based on the polygon vertices and it has dynamic

therefore it's a dynamic distinct partition. These areas are defined as positive area

negative area or mixed area. In the case of the positive area or the negative area

we can confirm the convexity or concavity of the vertices through simple distinguishing. The result of test indicates it is a simple

highly efficient and reliable algorithm with high speed requires only (n/4) multiplication and(12n) comparisons.