すべてのシェーダーに適用されるグローバルな Texture プロパティーを設定します
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
Usually this is used if you have a set of custom shaders that all use the same "global" texture (for example, custom diffuse-lighting cubemap). Then you can set the global property from script and don't have to setup the same texture in all materials.
See Also: SetGlobalColor, SetGlobalFloat; Material class, ShaderLab documentation.