Smooth an always updaing value?

Question

How would you go about smoothing an always updating value, The code:

int nLEDs = 25; // Number of LED's 
int sensitivity = 1;

int incomingByte = 0; 
int r = 0;
int g = 0;
int b = 0;
int a = 0;

void loop() {

        if (Serial.available() > 0) {
          incomingByte = Serial.parseInt();
          a = (255 / 100) * (incomingByte * sensitivity);
        }

       // some code 
}

void fade(){
  for(int i=0;i<nLEDs;i++){
   r = a;
   g = 0;
   b = 0;

   FTLEDColour col = { r , g , b };
 }
}

void ColourFade(){
  for(int i=0;i<nLEDs;i++){
   r = a;
   g = 255 - a;
   b = 0;

   FTLEDColour col = { r , g , b };
  }
}

On the fade methods, How would you go about smoothing the changes in the values instead of just jumping? If this is possible.

Answer 1

Instead of this:

value = NewValue

Do something like this:

value = (Value * 7 + NewValue + 7) / 8

This will cause value to be 7/8 the old value and 1/8 the new value, causing it to gradually "drift" to the new value, rather than jumping there all at once.

Answer 2

One option would be to use doubles instead of ints for your RGB (and other) values. And as is mentioned above, 255/100 will give you 2 rather than the 2.55 that you might be expecting.