interpolateColors = function( a, b, t ) {

				var deltaR = a.r - b.r;
				var deltaG = a.g - b.g;
				var deltaB = a.b - b.b;

				var c = new THREE.Color();

				c.r = a.r - t * deltaR;
				c.g = a.g - t * deltaG;
				c.b = a.b - t * deltaB;

				return c;

			}
Interpolates colors a and b following their relative distance
expressed by t.

@param float a
@param float b
@param float t
@returns {Color}