Canvas + Javascript水叠加

Question

Canvas + Javascript水叠加

我试图在画布上用Javascript制作水波,但是有些不对劲.

我的想法是制作3种不同颜色的波浪,但是它们相互透支.我无法弄清楚问题出在哪里.

<!DOCTYPE HTML>
<html>

  <style>

    <!-- 100% area -->
    body, html {
      height: 100%;
      width: 100%;
    }
  </style>

  <body>
    <canvas id="myCanvas" ></canvas>

    <script>
      //get window size
      var canvas = document.getElementById( "myCanvas" );
      canvas.width = window.innerWidth;   /// equal to window dimension
      canvas.height = window.innerHeight;

      // get the context
      var canvas = document.getElementById("myCanvas");
      var context = canvas.getContext('2d');


      // VARIABLES
      var frameCount=0;
      var N = 30;
      var positionXTeiler= Math.floor(canvas.width/(N-N/2));
      var size = 50;
      var xOffset = 200;
      var colors = [];
      var amplitude = 200;
      var wavesCount = 3;


      var init = function()
      {
        colors.push("rgba(0,0,128,1)");
        colors.push("rgba(0,0,255,1)");
        colors.push("rgba(47,86,233,1)");
      }

      var draw = function() {

        context.clearRect (0, 0, canvas.width, canvas.height);	


        for (i=0; i<N; i++) { 

          for (n=0; n<wavesCount; n++) { 
            var x = amplitude*Math.sin (frameCount*0.02+n*Math.PI/2);
            context.save();
            context.fillStyle = colors[n];
            context.beginPath();
            context.arc(positionXTeiler*i+x-xOffset,canvas.height-n*20,size,0,Math.PI*2,true);
            context.closePath();
            context.fill();

            context.restore();
          }
        }       
        // count the frame and loop the animation
        frameCount = frameCount+1;
        requestAnimationFrame(draw);
      };

      // start the loop
      init();
      draw();


    </script>

  </body>

</html>

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我的结果看起来应该像移动一样

Answer 1

Que*_*Roy 5

循环波,并在内部循环圆(即反转两个循环).

目标是在移动到下一个之前绘制波的所有圆.通过这种方式,您可以确保将波浪的圆圈绘制在前一个圆圈的顶部.

此外,您可能需要考虑使用基于时间的增量而不是帧数.动画帧不保证是常规的,它们的速率取决于用户的系统.

//get window size
var canvas = document.getElementById( "myCanvas" );
canvas.width = window.innerWidth;   /// equal to window dimension
canvas.height = window.innerHeight;

// get the context
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext('2d');

// VARIABLES
var frameCount=0;
var N = 30;
var positionXTeiler= Math.floor(canvas.width/(N-N/2));
var size = 50;
var xOffset = 200;
var colors = [];
var amplitude = 200;
var wavesCount = 3;


var init = function()
{
  colors.push("rgba(0,0,128,1)");
  colors.push("rgba(0,0,255,1)");
  colors.push("rgba(47,86,233,1)");
}

var draw = function() {
  context.clearRect (0, 0, canvas.width, canvas.height);  
  for (n=wavesCount-1; n>=0; n--) { 
    for (i=0; i<N; i++) { 
      var x = amplitude*Math.sin (frameCount*0.02+n*Math.PI/2);
      context.save();
      context.fillStyle = colors[n];
      context.beginPath();
      context.arc(positionXTeiler*i+x-xOffset,canvas.height-n*20,size,0,Math.PI*2,true);
      context.closePath();
      context.fill();
      context.restore();
    }
  }       
  // count the frame and loop the animation
  frameCount = frameCount+1;
  requestAnimationFrame(draw);
};

// start the loop
init();
draw();

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<!-- 100% area -->
body, html {
  height: 100%;
  width: 100%;
}

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<!DOCTYPE HTML>
<html>
  <body>
    <canvas id="myCanvas" ></canvas>
  </body>
</html>

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