Sunday 12 January 2020

Unable to use a `Symbol` for a `Group` with paper.js

I want to do an animation of a reaction-diffusion system with paper.js.

Here is a code which generates just one image:

<html>
  <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.12.2/paper-full.min.js"></script>
    <style>
      canvas {
        width: 400px;
        height: 400px;
        border: black 3px solid;
      }
    </style>
  </head>
  <body>
    <script>
      function subm_index(M, x){
        if (x<0)
          return x+M;
        if(x >= M)
          return x-M;
        return x;
      }
      function update_concentrations(X, L, DA, DB, f, k){ 
        var sum_a, sum_b, x1, y1, t;
        var m = X.A.length;
        var n = X.A[0].length;
        var A = new Array(m);
        var B = new Array(m);
        for(var i = 0; i < m; i++){
          A[i] = new Array(n);
          B[i] = new Array(n);
        }        
        for(var x = 0; x < m; x++) {
          for(var y = 0; y < n; y++){
            sum_a = 0.0;
            sum_b = 0.0;
            for(var i = -1; i <= 1; i++){
              for(var j = -1; j <= 1; j++){
                x1 = subm_index(m, x - i);
                y1 = subm_index(n, y - j);
                sum_a = sum_a + L[i+1][j+1] * X.A[x1][y1];
                sum_b = sum_b + L[i+1][j+1] * X.B[x1][y1];
              }
            }
            t = X.A[x][y]*X.B[x][y]*X.B[x][y];
            A[x][y] = X.A[x][y] + DA*sum_a - t + f*(1-X.A[x][y]);
            B[x][y] = X.B[x][y] + DB*sum_b + t - (k+f)*X.B[x][y];
          }
        }
        return {A: A, B: B};
      }
      function iterate_Gray_Scott(X, L, DA, DB, f, k, n){
        for(var i = 0; i < n; i++){
          X = update_concentrations(X, L, DA, DB, f, k); 
        }
        return X;
      }
      var L = [[0.05, 0.2, 0.05], [0.2, -1, 0.2], [0.05, 0.2, 0.05]];
      var DA = 1;
      var DB = 0.5;
      var f = 0.0545;
      var k = 0.062;
    </script>

    <script type="text/paperscript" canvas="quad">
      var pixels = 200;
      var gridSize = 2;
      var rectSize = 2;

      var A = new Array(pixels);
      var B = new Array(pixels);
      for(var i = 0; i < pixels; i++){
        A[i] = new Array(pixels);
        B[i] = new Array(pixels);
        for(var j = 0; j < pixels; j++){
          A[i][j] = 1;
          B[i][j] = Math.random() < 0.98 ? 0 : 1;
        }
      }
      var X = {A: A, B: B};

      X = iterate_Gray_Scott(X, L, DA, DB, f, k, 1000);
      
      for(var y = 0; y < pixels; y++){
        for(var x = 0; x < pixels; x++){
          var color = {
                        hue: X.B[x][y] * 360,
                        saturation: 1,
                        brightness: 1
                };
          var path = new Path.Rectangle(new Point(x, y) * gridSize, new Size(rectSize, rectSize));
          path.fillColor = color;
        }
      }
      project.activeLayer.position = view.center;
    </script>
    <canvas id="quad" resize></canvas>
  </body>
</html>

Now, here is a code which generates the animation:

<html>
  <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.12.2/paper-full.min.js"></script>
    <style>
      canvas {
        width: 400px;
        height: 400px;
        border: black 3px solid;
      }
    </style>
  </head>
  <body>
    <script>
      function subm_index(M, x){
        if (x<0)
          return x+M;
        if(x >= M)
          return x-M;
        return x;
      }
      function update_concentrations(X, L, DA, DB, f, k){ 
        var sum_a, sum_b, x1, y1, t;
        var m = X.A.length;
        var n = X.A[0].length;
        var A = new Array(m);
        var B = new Array(m);
        for(var i = 0; i < m; i++){
          A[i] = new Array(n);
          B[i] = new Array(n);
        }        
        for(var x = 0; x < m; x++) {
          for(var y = 0; y < n; y++){
            sum_a = 0.0;
            sum_b = 0.0;
            for(var i = -1; i <= 1; i++){
              for(var j = -1; j <= 1; j++){
                x1 = subm_index(m, x - i);
                y1 = subm_index(n, y - j);
                sum_a = sum_a + L[i+1][j+1] * X.A[x1][y1];
                sum_b = sum_b + L[i+1][j+1] * X.B[x1][y1];
              }
            }
            t = X.A[x][y]*X.B[x][y]*X.B[x][y];
            A[x][y] = X.A[x][y] + DA*sum_a - t + f*(1-X.A[x][y]);
            B[x][y] = X.B[x][y] + DB*sum_b + t - (k+f)*X.B[x][y];
          }
        }
        return {A: A, B: B};
      }
      function iterate_Gray_Scott(X, L, DA, DB, f, k, n){
        for(var i = 0; i < n; i++){
          X = update_concentrations(X, L, DA, DB, f, k); 
        }
        return X;
      }
      var L = [[0.05, 0.2, 0.05], [0.2, -1, 0.2], [0.05, 0.2, 0.05]];
      var DA = 1;
      var DB = 0.5;
      var f = 0.0545;
      var k = 0.062;
    </script>

    <script type="text/paperscript" canvas="quad">
      var pixels = 200;
      var gridSize = 2;
      var rectSize = 2;
      var A = new Array(pixels);
      var B = new Array(pixels);
      var Paths = new Array(pixels);
      for(var i = 0; i < pixels; i++){
        A[i] = new Array(pixels);
        B[i] = new Array(pixels);
        Paths[i] = new Array(pixels);
        for(var j = 0; j < pixels; j++){
          A[i][j] = 1;
          B[i][j] = Math.random() < 0.99 ? 0 : 1;
        }
      }
      var X = {A: A, B: B};

      for(var y = 0; y < pixels; y++){
        for(var x = 0; x < pixels; x++){
          var color = {
                        hue: X.B[x][y] * 360,
                        saturation: 1,
                        brightness: 1
                };
          Paths[x][y] = new Path.Rectangle(new Point(x, y) * gridSize, new Size(rectSize, rectSize));
          Paths[x][y].fillColor = color;
        }
      }

      var nframes = 100;

      var XX = new Array(nframes);
      XX[0] = X;
      for(var frm = 1; frm < nframes; frm++){
        XX[frm] = iterate_Gray_Scott(XX[frm-1], L, DA, DB, f, k, frm);
      }

      project.activeLayer.position = view.center;

      function onFrame(event){
        console.log(event.count);
        if(event.count < nframes){
          for(var y = 0; y < pixels; y++){
            for(var x = 0; x < pixels; x++){
              var color = {
                hue: XX[event.count].B[x][y] * 360,
                saturation: 1,
                brightness: 1
              };
              Paths[x][y].fillColor = color;
            }
          }
        }
      }
    </script>

    <canvas id="quad" resize></canvas>
  </body>
</html>

It works but the animation is not fluid enough. This is due to the double loop in onFrame, which consumes some time.

So I firstly tried to create an array containing nframes Group elements, each group containing pixels*pixels Rectangle elements. But this generated an out-of-memory.

So I tried to use a Symbol to save some memory. The code is below but it does not work, there is not a single image appearing.

<html>
  <head>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.12.2/paper-full.min.js"></script>
    <style>
      canvas {
        width: 400px;
        height: 400px;
        border: black 3px solid;
      }
    </style>
  </head>
  <body>
    <script>
      function subm_index(M, x){
        if (x<0)
          return x+M;
        if(x >= M)
          return x-M;
        return x;
      }
      function update_concentrations(X, L, DA, DB, f, k){ 
        var sum_a, sum_b, x1, y1, t;
        var m = X.A.length;
        var n = X.A[0].length;
        var A = new Array(m);
        var B = new Array(m);
        for(var i = 0; i < m; i++){
          A[i] = new Array(n);
          B[i] = new Array(n);
        }        
        for(var x = 0; x < m; x++) {
          for(var y = 0; y < n; y++){
            sum_a = 0.0;
            sum_b = 0.0;
            for(var i = -1; i <= 1; i++){
              for(var j = -1; j <= 1; j++){
                x1 = subm_index(m, x - i);
                y1 = subm_index(n, y - j);
                sum_a = sum_a + L[i+1][j+1] * X.A[x1][y1];
                sum_b = sum_b + L[i+1][j+1] * X.B[x1][y1];
              }
            }
            t = X.A[x][y]*X.B[x][y]*X.B[x][y];
            A[x][y] = X.A[x][y] + DA*sum_a - t + f*(1-X.A[x][y]);
            B[x][y] = X.B[x][y] + DB*sum_b + t - (k+f)*X.B[x][y];
          }
        }
        return {A: A, B: B};
      }
      function iterate_Gray_Scott(X, L, DA, DB, f, k, n){
        for(var i = 0; i < n; i++){
          X = update_concentrations(X, L, DA, DB, f, k); 
        }
        return X;
      }
      var L = [[0.05, 0.2, 0.05], [0.2, -1, 0.2], [0.05, 0.2, 0.05]];
      var DA = 1;
      var DB = 0.5;
      var f = 0.0545;
      var k = 0.062;
    </script>

    <script type="text/paperscript" canvas="quad">
      var pixels = 50;
      var gridSize = 2;
      var rectSize = 2;
      var A = new Array(pixels);
      var B = new Array(pixels);
      var Paths = new Array(pixels);
      for(var i = 0; i < pixels; i++){
        A[i] = new Array(pixels);
        B[i] = new Array(pixels);
        Paths[i] = new Array(pixels);
        for(var j = 0; j < pixels; j++){
          A[i][j] = 1;
          B[i][j] = Math.random() < 0.99 ? 0 : 1;
        }
      }
      var X = {A: A, B: B};

      var nframes = 50;

      var XX = new Array(nframes);
      XX[0] = X;
      for(var frm = 1; frm < nframes; frm++){
        XX[frm] = iterate_Gray_Scott(XX[frm-1], L, DA, DB, f, k, frm);
      }
      
      var Rects = [];
      for(var x = 0; x < pixels; x++){
        for(var y = 0; y < pixels; y++){
          var rect = new Path.Rectangle(new Point(x, y) * gridSize, new Size(rectSize, rectSize));
          var color = {
            hue: 1,
            saturation: 1,
            brightness: 1
          };
          rect.fillColor = color;
          rect.visible = false;
          Rects.push(rect);
        }
      }

      group = new Group(Rects);

      symbolGroup = new Symbol(group);

      var Groups = new Array(nframes);
      for(var frm = 0; frm < nframes; frm++){
        Groups[frm] = symbolGroup.place(view.center);
        var k = 0;
        for(var x = 0; x < pixels; x++){
          for(var y = 0; y < pixels; y++){
            Groups[frm].definition.definition.children[k].fillColor = {
              hue: XX[frm].B[x][y] * 360,
              saturation: 1,
              brightness: 1
            };
            k = k+1;
          }
        } 
        XX[frm] = null; // to free some memory
      } 

      project.activeLayer.position = view.center;

      function onFrame(event){
        if(event.count < nframes){
          console.log(event.count);
          Groups[event.count].visible = true;
          if(event.count > 0){
            Groups[event.count-1].visible = false; // to free some memory
          }
        }
      }
    </script>

    <canvas id="quad" resize></canvas>
  </body>
</html>

Can you help me to fix this last code?



from Unable to use a `Symbol` for a `Group` with paper.js

No comments:

Post a Comment