Throbber ( Take Deux )

throbber_deux.this.is.not.c

/*
 * "Throb" effect ( Part Deux )
 *
 * Paul Tagliamonte, 2010. ( Peace, Love and C++, baby )
 *
 *  This code is released under the Bacon license.
 *  If you like this code enough, consider sending me bacon.
 *
 *  That or GPL-3+. 
 *
 */

int ledPin   = 13;   // cute LED built into the Arduino
int adder    = 1;    // how much to jump by.
                     // This will be inverted later.

int slope       = 15; // y = (slope) x 
int accumulator = 0;  // part of bresie's algorithm

int cycle   = 10;    // duty ( hehehehe, doodie ) cycle
int on      = 5;     // How long "on" is per cycle.
int bottom  = 1;     // What "off" is

void setup() { pinMode(ledPin, OUTPUT); } // one line, dawg.

void loop() {

  /*
   * Credit where credit is due:
   *  The following is an adaption of Bresenham's line algorithm.
   *  
   * To future CS students, as well as current CS students:
   *  Please pay attention in class. You never know when the most
   *  inconsequential algorithm for the most obscure and backwards
   *  example will come in handy. This algorithm was originally
   *  to draw lines.
   *
   *  Now, the reason I use this is one big reason and one big reason
   *  only: It does not use division or floating point numbers to do
   *  computation. This was by design ( since such operations would
   *  bog down a CPU by a large factor when done over 10,000,000,000
   *  times ). Since the Arduino sucks with floating point numbers,
   *  and since it's a cute ARM processor, this is a perfect fit.
   *
   * Stay in school, kids. Listen to your parents.
   *
   * Oh yes, and go to class. For the love of christ, go to class.
   *
   */


  accumulator = accumulator + 1; // on cycle length
    if ( accumulator > slope ) { // if we've gone far enough X to jump a Y
        accumulator = 0;         //  then: - reset the counter
        on = on + adder;         //        - pop the "line" up one "Y"
        
        if ( on >= cycle || on <= bottom )
            adder = -adder; // if we're at the border, invert the adder for the next go-around.
    }
    
    digitalWrite(ledPin, HIGH); // BRIGHT!
    delay(on);                  // Wait for it!
    digitalWrite(ledPin, LOW);  // Darker then my coffee
    delay(cycle - on);          // Wait for it!
}