AlphaStepGen - OpenProcessing

mySketch
xxxxxxxxxx
 
/** 
 * AlphaStepGen (v1.0)
 * GoToLoop (2017/Sep/20)
 *
 * Forum.Processing.org/two/discussion/24193/descending-curve-function#Item_2
 * OpenProcessing.org/sketch/450448
 */
​
static final boolean JS = 1/2 == 1/2.;
final AlphaStep opaque = new AlphaStep();
​
void setup() {
  size(800, 600);
  smooth(3);
  frameRate(5);
​
  colorMode(RGB);
  ellipseMode(CENTER);
​
  strokeWeight(2.5);
  stroke(0);
​
  println(opaque.steps);
}
​
void draw() {
  background(-1);
  fill(255, 0, 0, opaque.nextAlpha());
  ellipse(width>>1, height>>1, width>>1, height>>1);
​
  if (JS)  return;
​
  String info = "Frame: " + frameCount + "  -  Alpha: " + opaque.toString();
  getSurface().setTitle(info);
}
​
class AlphaStep {
  static final int STEP = 5;
  float opacity = 255;
  final float[] steps = new float[1 + (int)opacity];
​
  AlphaStep() {
    for (int opac = (int)opacity, i = steps.length; i-- > 0; 
      steps[opac - i] = STEP * norm(i, opac, 0));
  }
​
  color nextAlpha() {
    return round(opacity -= steps[round(opacity)]);
  }
​
  String toString() {
    return nf(opaque.opacity, 0, 2);
  }
}