However, the subconscious mind is apparently very persistent, and a possible fix dawned on me. The four vertexes used to create the two triangles for the terrain do not (in all likelihood) line up to form a plane. The quadrilateral create by the points

*A,B,C*and

*D*is divided into two triangles using either the diagonal

*AC*or the diagonal

*BD*. In the terrain construction, the same diagonal is always chosen. The picture above illustrates the consequence -- the edges of the crater is very jagged.

Instead of a fixed choice, a better result is obtained when the diagonal is chosen with more care. Here is the rule I applied: take the diagonal that is the highest. This means that the quadrilateral will be always be convex (as seen from the outside) -- and some concave aspects of the generated terrain will disappear. In other words the terrain will have less jagged edges. To compute the

*highest*diagonal I take the diagonal that has the largest sum of the

*Y*component of its vertexes. Other methods also seem reasonable: for instance take the diagonal with the highest

*Y.*

The second picture shows the same view as the first using the

*largest sum*method. Definitely a noticeable improvement.