How to make an image fade to another image when a certain amount of light falls on a LDR?

blabla · October 2015

Hi, I have been trying to make an image transistion to another image when a certain amount of light falls on a LDR, and transistions back when that light is not shining on the LDR anymore. However, the piece of code is not working properly. I am new to processing, so there is a good chance that I am doing it completely wrong. It would be lovely if someone could help me achieve the fade in and out! Thanks in advance! Here is a part of my code, and what I have tried to do for the fade:

int transparency = 0;

void setup() {
  img = loadImage(imgFileName+"."+fileType);
  bla = loadImage("mermaid.jpg");
  size(img.width, img.height);
  image(img, 0, 0);

  println(Arduino.list());
  arduino = new Arduino(this, Arduino.list()[0], 57600);
  arduino.pinMode(ledPin, Arduino.OUTPUT);
  arduino.pinMode(sensorPin, Arduino.INPUT);
}
void draw() {
      int analogValue =  arduino.analogRead(sensorPin);
      println(analogValue);

      if (analogValue > 900) {
        noTint();
        image(bla, 0, 0);
      } else {
        while (column < width-1) {
          img.loadPixels(); 
          sortColumn();
          column++;
          img.updatePixels();
        }

        while (row < height-1) {
          img.loadPixels(); 
          sortRow();
          row++;
          img.updatePixels();
        }

     if (transparency < 255) {
          transparency++; 
        }
        tint(255, 255, 255, transparency);
        image(img, 0, 0);
        //automatically save the image 
        if (!saved && frameCount >= loops) {
          saveFrame(imgFileName+"_"+mode+".png");
          saved = true;
        }
      }
    }

benja · October 2015

So the values from arduino come in as expected? Then you can use analogValue like any other variable from there. Since your code is not complete, here is a simple example that fades an image depending on your mouse-position:

int treshold =50;
int alpha, fadeVal;
PImage img;

void setup() {
  img = loadImage("https:"  + "//processing.org/reference/images/image_0.png");
}

void draw() {
  //int value =  arduino.analogRead(sensorPin);
  int value = mouseX; 

  if (value>treshold)
    fadeVal =1;
  else
    fadeVal = -1;

  alpha= constrain(alpha+fadeVal, 0, 255);

  background(0);
  tint(255, alpha);
  image(img, 0, 0);
}

Chrisir · October 2015

i would distinguish between eval the analog signal and doing the fading

meaning: when the signal comes in, set a boolean or int marker state and do a fading (ignoring the signal state is == doFade) afterwards go to a state waitForDefade and when signal comes fade other direction (state == doDefade) then go to state waitForFade

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How to make an image fade to another image when a certain amount of light falls on a LDR?

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