Hello everybody, im creating  simple trail moving a ellipse(with mouse ) over a rectangle with alpha channel .
I have my alpha channel value at 1 but i would like that the fade out of the trail can be even slower. 1 is the lowest value that fill let me use for alpha , if i put 0.9 nothing happens. if I put more than 1 then the fading is faster.

How can i make if i want that the fading out can be slower?


thanks

1. 
   
   void setup(){
       size( 800, 800 );
   
   
   }
   
   
    
    
    
   void draw(){
   
          
       fill(0, 240, 0);
   
     ellipse(mouseX, mouseY ,30,30);
       noStroke();
       fill(0, 0, 0, 1);
       rect(0, 0, width , height );
     
   }