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 Creating Terrain (1 of 7) Back to Articles Page Next Page
The first part of the article will discuss the history of the technology and show how it has changed over the years. The second part will show some example of how to create of a terrain using the latest methods and compiler from Shaderlab. This article is designed to work with most Q3 engine type games and does not use any specific engine features.

The source files contain a collection of maps that were used to create the screenshots for this article. If you want to experiment with terrain blending and alpha fade brushwork while reading this article then I recommend you have a look at the source files.

I would like to thank Randy "ydnar" Reddig for constantly answering my questions and offering technical support with the finer details of the DotProduct2 system. Ken "kat" Beyer and Tom "shallow" Waters for providing excellent feedback on the content and layout.
 In the beginning ...    
MPTerra1 from TA The initial terrain was a collection of fixed sized triangles arranged in a mesh or grid.

The texturing was done via a metashader (a collection of special shaders) and the blends on the terrain were done via an external alpha map. (PCX file format)

The terrain brushes were groupered together and given special keys that specified total layers used, metashader information and external alpha map name / location.

The terrain was vertex lit and generally glowed because of the flat lighting model.
 Light mapped Terrain    
Fueldump from ET The next change was a subtle one with regards to technology but visually was a giant leap forward. The metashader was changed to use lightmaps instead of flat vertex light. This allowed for the rest of the map to cast shadows onto the terrain.

The terrain mesh and blending was still done as before but there were several third party tools available which could help with the creation process.

As the terrain textures were often stretch over large distances a detail texture was added to give the illusion of greater texture resolution. This did come at a price to the video card.
 DotProduct2 Terrain    
The Lost Abbey Finally a new system was developed and the metashader was replaced with a single shader. The steepness of the terrain was used for blending purposes and the triangle grid could now be any shape or size!

It was now easier to make realistic terrain shapes but this system had one flaw, each terrain shader could only support two textures.

The best solution at the time was to hide the material seams with paths or roads but even these textures could only be stretch so far. There was also no way to control the blends manually which meant that blending occurred at the mercy of the triangles.
 DotProduct2 + Alpha Fade Terrain    
Pyramid of the Magician With the Alpha Fade system, terrains can be blended easier with the DotProduct2 shader as the initial pass on the terrain and then fine tuning with Alpha Fade brushes afterwards.

The previous DotProduct2 texture limitation was broken and using the Alpha Fade brushes on the borders between different blends, multiple DotProduct2 shaders could now be seamlessly linked together.

The Alpha Fade brush system can work with any texture with an alpha channel and the relevant shader setup can also be blended with the same precision as terrains.
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