In several of my sketches (usually on black background) I want to draw things directly and "fade away" the display over time (while drawing new things on top of it.) I can achieve this fairly easy by drawing a black rectangle over the screen with a lower alpha value instead of using the background() command, f.e.
Code:

fill(0,0,0,fadeStrength); 
rect(0,0,width,height);  

(see example sketch)

This works fine, but it becomes problematic for  very low alpha-values of the fill colour (=slower fading) because it will not darken things to black completely anymore. My solution was to use this fading only every n-th frame, but for really smooth & slow fades, this does not work. Now I wonder what other "fading" solutions others have come up with...  Please share you code!

has something to do with the renderer you use.
It doesnt work when using Java2D but works when switching to P2D...

see the difference :


Code:

void setup() {
//  size(600,400);
  size(600,400,P2D);
  smooth();
  background(255);

}

void draw() {
 fill(0,1);
 rect(0,0,width,height);
 noStroke();
fill(255);
 ellipse(mouseX,mouseY,30,30);


}
 

Does this then mean it is a bug, or is there an explaination for it?
Anyway, any other suggestions for fading to black?