If any object travels to another object on a spiral path it is very much annoying to manually create the blending animation of their material. Through this material you can calculate their distance and blending animation of their material. This is very much helpful for creating such scenes like character is going near to fire or touching something with magic wand. Just watch the included video and you will get the idea how to use it.
copy script in your 3dsmax/script/startup folder. Restart 3dsmax. Access the santaDistMaterial from material editor.