We have already generated and rendered a heightmap, and now it’s time to add the next map layer — vegetation map based on biomes definition. The theme is boundless, but I’m going to cover both biomes generation and rending in a single post. The first reason that I’m a bit tired of it, the second — there are already some good tutorials available. From the procedural generation perspective theme was covered by Jon Gallant, Scott Turner, Amit Patel, Tommy Waters and Miguel Cepero. There are also a lot of materials prepared by Cartographers Guild members.
As you may notice, in all of the articles linked above biome generation is based on a the same principle. A well-known Whittaker diagram shows the distribution of vegetation types as a function of mean annual temperature and precipitation and hence very convent to use in a procedural generation. All that we need is to define precipitation and temperature for each polygon, prepare our own diagram and define the biomes based on these three components.