Class Diagrams for Terra3D


Other Fractal Landscapes

Aside from the plasma fractal used in my code, two other popular approaches are the fault fractal and the Fractal Brownian Motion (FBM) fractal.

A fault fractal creates a height map by drawing a random line through a grid and increasing the height values on one side of the line. If this is repeated several hundred times then a reasonable landscape appears. The main drawbacks are the lack of programmer control over the finished product and the length of time required to produce a convincing geography.

An FBM fractal is a combination of mathematical noise functions which generate random height values within a certain range. An important advantage of FBM is that each noise function has several parameters which can be adjusted to alter its effect. C++ code for creating clouds and landscapes with FBMs can be found in the article by Jesse Laeuchi: "Programming Fractals" from Games Programming Gems 2, section 2.8, pp.239-246, 2001.

A good online starting point for fractal terrain information is the Virtual Terrain Project page (http://www.vterrain.org/Elevation/artificial.html).

The j3d.org code repository (http://code.j3d.org) has an extensive set of packages related to terrain creation. There's a FractalTerrainGenerator class in org.j3d.geom.terrain that uses a plasma fractal approach similar to mine in which the heights are generated and converted to geometry with ElevationGridGenerator. Colors are assigned per vertices based on ramp values specified in ColorRampGenerator.

The use of colors at the vertices produces a pleasant blending effect. Unfortunately, it's impossible to combine texture mappings and colored nodes in Java 3D due to restrictions in the underlying OpenGL and DirectX systems.

Merlin Hughes wrote a JavaWorld article on plasma fractal terrains in 1998: "3D Graphic Java: Render Fractal Landscapes" (http://www.javaworld.com/javaworld/jw-08-1998/jw-08-step.html). He coded in Java without using Java 3D, so the implementation of tessellation, lighting and shading, viewpoint calculations, and rendering are low-level.

Plasma fractals were used by Mike Jacobs in his September 2004 article for Java Developer Journal about rendering a Martian landscape with Java 3D (http://www.sys-con.com/story/?storyid=46231&DE=1). His terrain utilizes vertex coloring rather than textures.



Killer Game Programming in Java
Killer Game Programming in Java
ISBN: 0596007302
EAN: 2147483647
Year: 2006
Pages: 340

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