It's hard to make it without such interpolation, since my terrain is infinite and automatically generated using perlin noise.
I have actually no idea on how to use the texture array to make interpolations between them ( -  -  - ... - [N] and so on) without sending N weights to every vertex to tell the shader which texture it should sample.
Could you help me with that, please?
Is it possible to give texture index a float value and get blending this way? E.g: