I briefly talked about Canvas in HTML before. This time I completed the "wave effect" (water waves rising) based on Canvas.

（O(∩_∩)O hahaha~ Author I can watch this animation all afternoon)

Rising water wave.gif

• Animation analysis
  Composition: Bezier curve
  Canvas: Canvas
  Effect: wave rising (rising, fluctuation)
  Trigger condition: Click the button

Algorithm implementation analysis: Starting from the sin()
function, the larger the sin(), the greater the fluctuation of the wave. Simply put, the wave effect animation is realized by continuously changing the sin() value

<button type="button"
        onclick="Beisizer()"//点击时触发JS事件
        onmouseover="bcd()"//鼠标经过时JS事件
        onmouseleave="out()"//鼠标离开时JS事件
        id="Anniu">确  &nbsp &nbsp  &nbsp  &nbsp  &nbsp  &nbsp &nbsp  &nbsp  &nbsp  &nbsp  定</button>

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

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//获取画布
 var beisizer = document.getElementById("Theback");
 var ContenofBeisizer = beisizer.getContext("2d");

 //设置波浪海域（海浪宽度，高度）
 var beisizerwidth = beisizer.width;
 var beisizerheight = beisizer.height;
 var beisizerlinewidth = 2;

//曲线
 var sinX = 0;
 var sinY = beisizerheight/2.0;
//轴长
 var axisLenght = beisizerwidth;
//弧度宽度
 var waveWidth = 0.014;
//海浪高度
 var waveHeight = beisizerheight / 15.0;
ContenofBeisizer.lineWidth = beisizerlinewidth;

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   var drawSin = function (xofspeed) {
        ContenofBeisizer.save();
        //存放贝塞尔曲线的各个点
        var points = [];
        ContenofBeisizer.beginPath();
        //创建贝塞尔点
        for (var x = sinX;x < sinX +axisLenght;x+=80/axisLenght){
           // var y = -Math.sin((sinX+x)*waveWidth);  测试请解开注释，注释下一行
            var y = -Math.sin((sinX+x)*waveWidth+xofspeed);

            // points.push([x,sinY + y * waveHeight]); 测试请解开注释，注释下一行
            points.push([x,rand+y*waveHeight]);      

          //  ContenofBeisizer.lineTo(x,sinY + y * waveHeight);  测试请解开注释，注释下一行
         ContenofBeisizer.lineTo(x,rand + y * waveHeight);   
        }

        ContenofBeisizer.lineTo(axisLenght,beisizerheight);
        ContenofBeisizer.lineTo(sinX,beisizerheight);
        ContenofBeisizer.lineTo(points[0][0],points[0][1]);
        ContenofBeisizer.stroke();
        ContenofBeisizer.restore();

       //贝塞尔曲线样式设置
        ContenofBeisizer.strokeStyle = "#3bc777";
        ContenofBeisizer.fillStyle = "#3bc777";
        ContenofBeisizer.fill();
    };

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This code has completed the drawing of

static Bezier curve. You can try to run it by untying the following statement to see the effect. .
var y = -Math.sin((sinX+x)*waveWidth);
points.push([x,rand+y*waveHeight]);
var y = -Math.sin((sinX+x)*waveWidth+xofspeed);Run the method to execute drawSin()

var speed = 0.1; The larger the value, the faster the speed.
var xofspeed = 0; The lateral offset of the wave
var rand = beisizerheight;Wave height

    var rendY = function () {
        ContenofBeisizer.clearRect(0,0,beisizerwidth,beisizerheight);

        //控制海浪高度
        var tmp = 0.1;
        rand-=tmp;
        var b = beisizerheight - rand;

        //控制循环涨潮
        if (parseInt(b)==beisizerheight){
            rand = beisizerheight;
        }

        drawSin(xofspeed);
        drawSinl(xofspeed);
        xofspeed += speed;
        requestAnimationFrame(rendY);
    };

Call itself to generate different heights to produce a wave effect. The attribute values ​​set here can be understood together with the fourth step of drawing the Bezier curve.

Running method rendY();

Free h5 online video tutorial

HTML5 full version manual

php.cn original html5 video tutorial

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