// Daniel Shiffman

// http://www.learningprocessing.com

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// Example 16-14: Overall motion

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// Variable for capture device

let video;

// Previous Frame

let prevFrame;

// How different must a pixel be to be a "motion" pixel

let threshold = 50;

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function setup() {

  createCanvas(windowWidth, windowHeight);

  pixelDensity(1);

  video = createCapture(VIDEO);

  video.size(width, height);

  video.hide();

  // Create an empty image the same size as the video

  prevFrame = createImage(video.width, video.height, RGB);

}

​

function draw() {

  background(255, 128, 128);

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  video.loadPixels();

  prevFrame.loadPixels();

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  let totalMotion = 0;

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  // Begin loop to walk through every pixel

  for (let x = 0; x < video.width; x++) {

    for (let y = 0; y < video.height; y++) {

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      // Step 1, what is the location into the array

      let loc = (x + y * video.width) * 4;

      // Step 2, what is the previous color

      let r1 = prevFrame.pixels[loc   ]; 

      let g1 = prevFrame.pixels[loc + 1];

      let b1 = prevFrame.pixels[loc + 2];

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      // Step 3, what is the current color

      let r2 = video.pixels[loc   ]; 

      let g2 = video.pixels[loc + 1];

      let b2 = video.pixels[loc + 2];

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      // Step 4, compare colors (previous vs. current)

      let diff = dist(r1, g1, b1, r2, g2, b2);

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      totalMotion += diff;

    }

  }

​

  // Save frame for the next cycle

  if (video.canvas) {

    prevFrame.copy(video, 0, 0, video.width, video.height, 0, 0, video.width, video.height); // Before we read the new frame, we always save the previous frame for comparison!

  }

​

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  // averageMotion is total motion divided by the number of pixels analyzed.

  let avgMotion = totalMotion / (video.width * video.height); 

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  // Draw a circle based on average motion

  noStroke();

  fill(0);

  let r = avgMotion * 3;

  textAlign(CENTER);

textSize(r);

textFont('Courier');

// fill(255)

  text('uncurl yourself',width/2, height/2);

  //ellipse(width/2, height/2, r, r);

​

}