Generation of (Rollercoaster/Transport Tycoon) terrain

Question

I am currently trying to generate the type of terrain they have in Rollercoaster Tycoon / Transport Tycoon alike games.

This image shows the kind of terrain that I'm trying to achieve. Screenshot of Transport Tycoon

Of what I can conclude it looks like there is 13 different tile shapes. 1 (Flat) + 4 (Slope for each direction) + 4 (Half Flat, Half Slope up) + 4 (Half flat, Half Slope down) = 13 shapes.

Is there any public algorithm for generating this kind of terrain, or will I just have to write it myself :)?

Answer 1

The type of square depends on the heights in each vertex of the grid, so what you want is an algorithm to generate the heights at each vertex. The rules in this case (transport tycoon) is that the four corners of one tile has at most a height difference of two steps, and in fact at most two vertices can have the 2 step difference. T

A common way of generating terrain is through simulated erosion, that is, you start with a random terrain and erode it by smoothing and simulated rivers etc. until you get what you need. Given the restrictions in the TT terrain, I doubt this is how it is made. Apart from the constraints of the slopes, the game also requires that the terrain is reasonably flat. The standard terrain generation of OpenTTD appears to be a repeated random heighteing/lowering of vertices.

You can view the terrain generation algorithm at openttd.org http://svn.openttd.org/trunk/src/landscape.cpp
(Search for "GenerateLandscape").

This open source version supports several generation methods, both erosion based ("Terragenesis") and randomized.