I have a few key features that I want for my game's terrain mesh, but putting it all together into an terrain editor is becoming a headache. I need some advice from someone more experienced than myself. Perhaps there is some design pattern or object-oriented trickery to add some abstraction and turn this mess into something manageable.
I am creating my terrain mesh as a problem of dynamic constrained triangulation. I start with a regular triangulation of a 2D plane into equilateral triangles, and then as I draw the game's map the existing edges and vertices are automatically removed to make room for the edges and vertices I'm drawing, and naturally the reverse happens when I erase. There are fairly simple algorithms for inserting individual vertices and edges into a triangulated plane. Using a half-edge data structure to represent the triangulation makes it quite manageable.
Unfortunately there are a few additional important features. For one, a game map should be an infinite plane in all directions. The obvious solution to this is to break up the mesh into regular pieces, each one separately triangulated but sharing common points along their edges so that the multiple meshes fit together seamlessly in the game. The user should be able to draw map features across the boundaries of the map pieces seamlessly, without needing to care where one map piece begins and another one ends. An ordinary half-edge data structure doesn't have anything to deal with that and it would be nice if I could manage that complexity so it doesn't seriously affect my triangulation algorithms.
Perhaps I'm asking for trouble, but I also want the terrain mesh to be able to change while the game is playing. I'm not so greedy as to try to implement animated terrain, but I would at least like to be able to remove a designated region of the map and substitute an alternative map of the same shape. We might think of it as having a hole in the map that can be filled by any one of several appropriately shaped meshes. Once we've got these meshes it will be trivial to pop them in and out during the game, but again it's another complication of the editor. Keeping the boundaries of the designated regions aligned with the rest of the map and allowing new edges to be drawn across that boundary is making the editor too complicated for comfort.
What are the appropriate abstractions to use for this kind of situation? These seem like relatively simple features, but my design is turning into a tangled mess. What am I doing wrong? An ordinary half-edge structure doesn't seem to be the right tool for this job, but what would be the right tool?
