Matte_Material() gives a copy of a material with its glossiness damped and its weathering on: the faces cut out of a polished surface, as the sides of a worn rail head, darken and lose the shine by the userdata of their vertices. Tinted_Material() gives a copy whose texture is tinted to a colour as far instead. Both are made once per material.
The weathering and the tint colour have a param slot of their own, param[3]: the shaders of the materials use all four components of param[2] among them (detail, parallax, water, the terrain placement), and light_common.glsl is included in all of them. MAX_PARAMS grows from 3 to 4, the model UBO by 16 bytes. Neither copy is made when another param of the shader lies on the components it would set.
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