Sets a global vector property for all shaders.
Global properties are used if a shader needs them but the material does not have them defined (for example, if the shader does not expose them in Properties block).
Usually this is used if you have a set of custom shaders that all use the same "global" vector (for example, wind direction). Then you can set the global property from script and don't have to setup the same vector in all materials.
See Also: SetGlobalFloat, SetGlobalColor, SetGlobalTexture; Material class, ShaderLab documentation.