private void setupKeys() {
        flyCam.setMoveSpeed(50);
        inputManager.addMapping("wireframe", new KeyTrigger(KeyInput.KEY_T));
        inputManager.addListener(actionListener, "wireframe");
        inputManager.addMapping("triPlanar", new KeyTrigger(KeyInput.KEY_P));
        inputManager.addListener(actionListener, "triPlanar");
    }
Demonstrates how to use terrain.
The base terrain class it uses is TerrainQuad, which is a quad tree of actual
meshes called TerrainPatches.
There are a couple options for the terrain in this test:
The first is wireframe mode. Here you can see the underlying triangle strip structure.
You will notice some off lines; these are degenerate triangles and are part of the
triangle strip. They are only noticeable in wireframe mode.
Second is Tri-Planar texture mode. Here the textures are rendered on all 3 axes and
then blended together to reduce distortion and stretching.
Third, which you have to modify the code to see, is Entropy LOD calculations.
In the constructor for the TerrainQuad, un-comment the final parameter that is
the LodPerspectiveCalculatorFactory. Then you will see the terrain flicker to start
while it calculates the entropies. Once it is done, it will pick the best LOD value
based on entropy. This method reduces "popping" of terrain greatly when LOD levels
change. It is highly suggested you use it in your app.

@author bowens
jme3-examples/src/main/java/jme3test/terrain/TerrainTest.java