用javascript html5将整个图像包裹在圆柱形杯子上答案

【问题标题】：Wrap whole image on cylindrical cup in javascript html5用javascript html5将整个图像包裹在圆柱形杯子上
【发布时间】：2017-03-03 17:14:36
【问题描述】：

我想将图像包裹在圆柱形杯子上。我正在使用 html5 和 Java 脚本来实现这个解决方案。我从这个链接中得到了一些想法：https://stackoverflow.com/questions/31424117/。但我没有从这个链接得到解决方案。

我想将剩余的图像包裹在杯子后面，就像模制剩余的部分并添加一些旋转按钮。

<canvas id="canvas"></canvas>

        <script>
            var canvas = document.getElementById("canvas");
            var ctx = canvas.getContext("2d");

            var productImg = new Image();
            productImg.onload = function () {
                var iw = productImg.width;
                var ih = productImg.height;
                console.log("height");

                canvas.width = iw;
                canvas.height = ih;

                ctx.drawImage(productImg, 0, 0, productImg.width, productImg.height, 0, 0, iw, ih);

                //start();

                // outline
                /*ctx.beginPath();
                 ctx.moveTo(88, 235.734375);
                 ctx.bezierCurveTo(88, 234.734375, 204, 298, 327, 234.734375);
                 ctx.stroke();*/
            };
            productImg.src = "https://d2z4fd79oscvvx.cloudfront.net/0018872_inspirational_teacher_mug.jpeg";

            var img = new Image();
            img.onload = start;
            img.src = "http://blog.foreigners.cz/wp-content/uploads/2015/05/Make-new-friends.jpg";
            var pointer = 0;        


            function start() {

                var iw = img.width;               
                var ih = img.height;
                //canvas.width = iw + 20;
                //canvas.height = ih + 20;

                var x1 = 125;
                var y1 = 130;
                var x2 = 180;
                var y2 = 190;
                var x3 = 405;
                var y3 = 150;

                // calc line equations slope & b (m,b)
                var unitT = 1 / iw;

                // draw vertical slices
                for (var X = 0, t = 0; X < iw; X++, t += unitT) {
                    var xTop = (1 - t) * (1 - t) * x1 + 2 * (1 - t) * t * x2 + t * t * x3;                   
                    var yTop = (1 - t) * (1 - t) * y1 + 2 * (1 - t) * t * y2 + t * t * y3;
                    ctx.drawImage(img, X + pointer, 0, 1, ih, xTop, yTop, 0.85, ih - 600);
                }

如果我在上面的代码中改变指针值，剩下的图像拉伸。

var pointer = 100 ;

我想将图像包裹在整个杯子上并左右旋转。

【问题讨论】：

对此做了一个小插曲：plnkr.co/edit/5LAv3f8KLZ8X8zOH4yUc
-1。花了更多时间查看这个问题后，我意识到上面链接的问题有一个 functioning jsfiddle，OP 复制得很糟糕，这是这对他们不起作用的主要原因。不过，@Varun，你需要做一些几何：你一次只能看到一半的图像，你需要一个像余弦这样的三角函数来做投影，但你应该从修改你找到的工作示例开始一步一步来。

标签： javascript jquery css html

【解决方案1】：

我在你的 plunkr 周围玩了一段时间，然后想出了这个： http://plnkr.co/edit/83xAr99FjswWg0GHjDvJ?p=preview

function start() {

    var iw = img.width;
    var ih = img.height;

    var xOffset = 125,
        yOffset = 122;

    var a = 122.0;
    var b = 30.0;

    var scaleFactor = iw / (2*a); //how many times original image is greater compared to our rendering area?

    // draw vertical slices
    for (var X = 0; X < iw; X+=1) {
      var y = b/a * Math.sqrt(a*a - (X-a)*(X-a)); // ellipsis equation
      ctx.drawImage(img, X * scaleFactor, 0, 6, ih, X + xOffset, y + yOffset, 1, ih - 605 + y/2);
    }
}

我把这个省略号方程http://www.mathopenref.com/coordgeneralellipse.html 转换成我可以从相关的X 坐标得到Y 坐标的形式。

你可以多玩一下我的plunkr，让图像更准确地覆盖杯子，但距离现实还很远，因为这种方法没有考虑到杯子表面的不同闪电特征。

【讨论】：

但我想将拉伸图像包裹在杯子后面，旋转杯子后它会显示出来。如果您对此有所了解，请帮助我。

【解决方案2】：

function canvas1() {
  var canvas = document.getElementById("canvas1");
  var ctx = canvas.getContext("2d");

  var productImg = new Image();
  productImg.onload = function() {
    var iw = productImg.width;
    var ih = productImg.height;
    console.log("height");

    canvas.width = iw;
    canvas.height = ih;

    ctx.drawImage(productImg, 0, 0, productImg.width, productImg.height,
      0, 0, iw, ih);
    loadUpperIMage()
  };

  productImg.src = "http://res.cloudinary.com/pussyhunter/image/upload/c_scale,f_auto,h_350/left_handle_cup_i7ztfs.jpg"


  function loadUpperIMage() {
    var img = new Image();


    img.src = "https://media1.giphy.com/media/j3uyvaaslUxNe/200_s.gif"
    img.onload = function() {

      var iw = img.width;
      var ih = img.height;

      var xOffset = 102, //left padding
        yOffset = 110; //top padding

      //alert(ih)
      var a = 75.0; //image width
      var b = 10; //round ness

      var scaleFactor = iw / (4 * a);

      // draw vertical slices
      for (var X = 0; X < iw; X += 1) {
        var y = b / a * Math.sqrt(a * a - (X - a) * (X - a)); // ellipsis equation
        ctx.drawImage(img, X * scaleFactor, 0, iw / 9, ih, X + xOffset, y + yOffset, 1, 174);
      }
    };
  }

};

function canvas2() {

  var canvas = document.getElementById("canvas2");
  var ctx = canvas.getContext("2d");

  var productImg = new Image();
  productImg.onload = function() {
    var iw = productImg.width;
    var ih = productImg.height;
    console.log("height");

    canvas.width = iw;
    canvas.height = ih;

    ctx.drawImage(productImg, 0, 0, productImg.width, productImg.height,
      0, 0, iw, ih);
    loadUpperIMage()
  };


  productImg.src = "http://res.cloudinary.com/pussyhunter/image/upload/h_350/canter_handle_cup_xyxhdd.jpg"

  function loadUpperIMage() {
    var img = new Image();

    img.src = "https://media1.giphy.com/media/j3uyvaaslUxNe/200_s.gif"

    img.onload = function() {

      var iw = img.width;
      var ih = img.height;

      // alert(iw)

      var xOffset = 101, //left padding
        yOffset = 110; //top padding

      var a = 75.0; //image width
      var b = 10; //round ness

      var scaleFactor = iw / (4 * a);

      // draw vertical slices
      for (var X = 0; X < iw; X += 1) {
        var y = b / a * Math.sqrt(a * a - (X - a) * (X - a)); // ellipsis equation
        ctx.drawImage(img, X * scaleFactor, 0, iw / 3, ih, X + xOffset, y + yOffset, 1, 174);

      }
    };
  }

};

function canvas3() {

  var canvas = document.getElementById("canvas3");
  var ctx = canvas.getContext("2d");

  var productImg = new Image();
  productImg.onload = function() {
    var iw = productImg.width;
    var ih = productImg.height;

    canvas.width = iw;
    canvas.height = ih;

    ctx.drawImage(productImg, 0, 0, productImg.width, productImg.height,
      0, 0, iw, ih);
    loadUpperIMage()
  };

  productImg.src = "http://res.cloudinary.com/pussyhunter/image/upload/h_350/right_handle_cup_dsdhr7.jpg"


  function loadUpperIMage() {
    var img = new Image();

    img.src = "https://media1.giphy.com/media/j3uyvaaslUxNe/200_s.gif"

    img.onload = function() {

      var iw = img.width;
      var ih = img.height;

      //alert(iw)

      var xOffset = 102, //left padding
        yOffset = 110; //top padding

      var a = 75.0; //image width
      var b = 10; //round ness

      var scaleFactor = iw / (3 * a);

      // draw vertical slices
      for (var X = 0; X < iw; X += 1) {
        var y = b / a * Math.sqrt(a * a - (X - a) * (X - a)); // ellipsis equation
        ctx.drawImage(img, X * scaleFactor, 0, iw / 1.5, ih, X + xOffset, y + yOffset, 1, 174);
      }
    };
  }

};

setTimeout(function() {
  canvas1()
}, 1000);
setTimeout(function() {
  canvas2()
}, 2000);
setTimeout(function() {
  canvas3()
}, 3000);

function updateItems(delta)
{
    var $items = $('#group').children();
    var $current = $items.filter('.current');
    $current = $current.length ? $current : $items.first();
    var index = $current.index() + delta;
    // Range check the new index
    index = (index < 0) ? 0 : ((index > $items.length) ? $items.length : index); 
    $current.removeClass('current');
    $current = $items.eq(index).addClass('current');
    // Hide/show the next/prev
    $("#prev").toggle(!$current.is($items.first()));    
    $("#next").toggle(!$current.is($items.last()));    
}
$("#next").click(function () {
    updateItems(1);
});
$("#prev").click(function () {
    updateItems(-1);
});
// Cause initial selection
updateItems(0);

#group div{
    display: none;
}
#group div.current{
    display: block;
   
}
#next, #prev{
    width: 100px;
    height 40px;
   cursor:pointer;
   color:red;
   position:fixed;
}
#next{
  float: right;  
} 
#prev{
  float: left;
  margin-left:40px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.1/jquery.min.js"></script>
<div id="next">next</div>
<div id="prev">prev</div>
<div id="group" >
  <div>
    <canvas id="canvas1"></canvas>
  </div>

  <div>
    <canvas id="canvas2"></canvas>
  </div>

  <div>
    <canvas id="canvas3"></canvas>
  </div>
</div>

【讨论】：