Perlin Noise work miracles for vast landscapes. A simple 2D Perlin Noise function can generate an infinite, non-repeating terrain for you. To do the textures, there are many ways. You can assign a height range for each texture. When a terrain vertex is within this range, you calculate it''s proximity to the upper and lower boundaries of the range in the form of a percentage (point A is 23.7% from lower bound and 76.3% from upper bound). Then you mix 23.7% of the texture represented by the lower bound and 76.3% of the texture from the upper bound. This will generate smooth transitions from grass to rock, rock to snow, etc... I am a bad teacher, so sorry if this doesn''t make any sense, but if any ofyou have tried this technique, it works great and you make a terrain that you can drive/walk on literally forever or until your computer falls apart from erosion.