decreasingPercent = GenGetSpriteTimerAFade(Sprite)
decreasingPercent = GenGetSpriteTimerBFade(Sprite)
These functions return a decreasing fractional percent which is proportional to the amount of time that has past. When the timer is first set these functions would return 1.0. Then, as time elapses the fractional percent returned decreases to 0.0 when the time expires.