public static float interpolateLinear(float scale, float startValue, float endValue) {
        if (startValue == endValue) {
            return startValue;
        }
        if (scale <= 0f) {
            return startValue;
        }
        if (scale >= 1f) {
            return endValue;
        }
        return ((1f - scale) * startValue) + (scale * endValue);
    }
Linear interpolation from startValue to endValue by the given percent.
Basically: ((1 - percent) * startValue) + (percent * endValue)

@param scale
           scale value to use. if 1, use endValue, if 0, use startValue.
@param startValue
           Beginning value. 0% of f
@param endValue
           ending value. 100% of f
@return The interpolated value between startValue and endValue.
jme3-core/src/main/java/com/jme3/math/FastMath.java