Been asked for several times already with the same question. So, here is an option with tween.js and modified MeshLambertMaterial: Texture transition - JSFiddle - Code Playground
Not the ultimate solution, but a starting point.

Been asked for several times already with the same question. So, here is an option with tween.js and modified MeshLambertMaterial: Texture transition - JSFiddle - Code Playground
Not the ultimate solution, but a starting point.
