private static float getY(float x, float z, float max) {
        float yMaxHeight = 8;
        float xv = FastMath.unInterpolateLinear(FastMath.abs(x - (max / 2)), 0, max) * FastMath.TWO_PI;
        float zv = FastMath.unInterpolateLinear(FastMath.abs(z - (max / 2)), 0, max) * FastMath.TWO_PI;

        float xComp = (FastMath.sin(xv) + 1) * 0.5f;
        float zComp = (FastMath.sin(zv) + 1) * 0.5f;

        return -yMaxHeight * xComp * zComp;
    }
Creates a curved "floor" with a MeshCollisionShape provided as the RigidBodyControl's collision shape.
Surface has four slightly concave corners to allow for multiple tests and minimize falling off the edge
of the floor.

@param assetManager for loading assets
@param floorDimensions width/depth of the "floor" (X/Z)
@param position sets the floor's local translation
@return a new Geometry
jme3-examples/src/main/java/jme3test/bullet/PhysicsTestHelper.java