how to fade pixels?

Programming Questions

luxxnatura

in Programming Questions • 2 years ago

I'm using this code based on the "pointellism" tutorial, which writes the image pixels to the screen wonderfully, but I'm wondering how to make the pixels fade away in the same way? any help would be appreciated.

import fullscreen.*;
import processing.video.*;
FullScreen fs;
PImage erin;
void setup() {
frameRate(60);
size(800,800);
fs = new FullScreen(this);
fs.enter();
noCursor();
erin = loadImage("erin2.jpg");
background(0);
smooth();
}
void draw() {
drawCells();
}
void drawCells() {
int x = int(random(erin.width));
int y = int(random(erin.height));
int loc = x + y*erin.width;
loadPixels();
float r = red(erin.pixels[loc]);
float g = green(erin.pixels[loc]);
float b = blue(erin.pixels[loc]);
noStroke();
fill(r,g,b,100);
ellipse(x,y,5,5);
}

Replies(3)

nardove

Re: how to fade pixels?

2 years ago

try decreasing the alpha value in the line 27

fill(r,g,b, alphaVal);

By assigning something like an alphaVal variable and decrementing on every frame

- rS

luxxnatura

Re: how to fade pixels?

2 years ago

if I adjust the alpha value on line 27, it decreases the alpha when the pixels are first drawn to the page. This is not exactly what i want.

below is my revised routine for drawCells(). I'm not sure that I'm writing this statement correctly, or even in the right place.

void drawCells() {
int alphaVal = 100;

int x = int(random(erin.width));
int y = int(random(erin.height));
int loc = x + y*erin.width;

loadPixels();

float r = red(erin.pixels[loc]);
float g = green(erin.pixels[loc]);
float b = blue(erin.pixels[loc]);

noStroke();
fill(r,g,b,alphaVal);
ellipse(x,y,5,5);
while (alphaVal > 0) alphaVal--;
}

PhiLho

Re: how to fade pixels?

2 years ago

" decrementing on every frame" means "on each call of draw()", thus on each call of your drawCells() function.
Your while loop will only zeroes alphaVal in a slow way...

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