psatkha
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Um... in the alpha version, they are used for everything except effects, and Granny is also used in Blitzkrieg, it seems.
It is used to darken the water through a normal map; I'm not entirely sure here. Look at the textures of the normal map from the closed beta version that psatkha provided and see how the water looks with them.
Yes, in Beta 2 for sure. Thanks to the previous research on the Beta 2 game by the highly respected comrade CrazyPill, it became possible to export meshes in the Nival format and Granny, but again, the engine of the fifth game is a heavily modified engine of Beta 2!
С уважением, Psatkha (Псатха) 
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Неудачное планирование ведёт к неудаче ...
NCF - мод, добавляющий дополнительных существ в HeroesV 3.1
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Неудачное планирование ведёт к неудаче ...
NCF - мод, добавляющий дополнительных существ в HeroesV 3.1