awesome! thanks john.
another question-
i am using a max/msp patch to generate the random number (0-255) going to arduino via serial usb. when the button is pressed it streams these values live and when it lets go the trail stops building and trails off, continuing down the strip with the last values it received with the fade just like the code says it will. what i want to do is- when the button is released and the trail starts to fade as it travels down in its group, instead of just keeping the last values it received, i want it to keep displaying live values as the trail goes down. so lets say the light trail is two feet long going down the 20 foot strip, instead of a bunch of old values going from one to the next led, i want the trail to keep changing with live serial values but remain in its two foot section after the button is released.