来自 IT技术新闻 2018-12-27 09:38 的文章

canvas-star7.html,html5canvas

canvas-star7.html,html5canvas

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>添加土地</title>
</head>
<body>
    <canvas id="canvas" >
        The current browser does not support Canvas, can replace the browser a try!
    </canvas>

    <script>

        window.onload = function(){
            var canvas = document.getElementById('canvas');

            canvas.width = 1200;
            canvas.height = 800;

            if(canvas.getContext('2d')){
                var context = canvas.getContext('2d');

                // context.fillStyle = "#000";

                // 背景
                var skyStyle = context.createRadialGradient(canvas.width/2,canvas.height,0,canvas.width/2,canvas.height,canvas.height);
                skyStyle.addColorStop(0.0,'#035');
                skyStyle.addColorStop(1.0,'black');
                context.fillStyle = skyStyle;
                
                context.fillRect(0,0,canvas.width,canvas.height)

                // 星星
                for(var i=0;i<200;i++){
                    var r = Math.random() * 5 + 5;
                    var x = Math.random() * canvas.width;
                    var y = Math.random() * canvas.height * 0.65;
                    var a = Math.random() * 360;

                    drawStar(context , x , y , r , a )
                }

                // 月亮
                fillMoon(context,2,900,200,100,30)

                // 土地
                drawLand(context)

            }else{
                alert('当前游览器不支持Canvas,请更换游览器后再试!');
            }
        }

        function drawLand(cxt){
            cxt.save();
                cxt.beginPath();
                    cxt.moveTo(0,600);
                    cxt.bezierCurveTo(540,400,660,800,1200,600);
                    cxt.lineTo(1200,800);
                    cxt.lineTo(0,800);
                cxt.closePath();

                var landStyle = cxt.createLinearGradient(0,800,0,0);
                landStyle.addColorStop(0.0,'#030');
                landStyle.addColorStop(1.0,'#580');
                cxt.fillStyle = landStyle;

                cxt.fill();

            cxt.restore();
        }

        function fillMoon(cxt,d,x,y,R,rot,fillColor){
            cxt.save();
                cxt.translate(x,y);
                cxt.rotate(rot*Math.PI/180);
                cxt.scale(R,R);
                pathMoon(cxt,d);
                cxt.fillStyle = fillColor || "#fb5";
                cxt.fill();
            cxt.restore();
        }

        function pathMoon(cxt,d){
            cxt.beginPath();
                cxt.arc(0,0,1,0.5*Math.PI,1.5*Math.PI,true);
                moveTo(0,-1);
                cxt.arcTo(d,0,0,1,dis(0,-1,d,0)/d);
            cxt.closePath();
        }

        function dis(x1,y1,x2,y2){
            return Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2))
        }

        function createBackgroundCanvas(){
            var backCanvas = document.createElement("canvas");
            backCanvas.width = 100;
            backCanvas.height = 100;
            var backCanvasContext = backCanvas.getContext('2d');
            drawStar(backCanvasContext,50,50,50,0);
            return backCanvas
        }

        function drawStar(cxt,x,y,R,rot){
            cxt.save();

                cxt.translate(x,y);
                cxt.rotate(rot/180*Math.PI);
                cxt.scale(0.05*R,0.05*R)

                starPath(cxt);

                cxt.fillStyle = "#fb3";
                cxt.strokeStyle = "#fd5";
                cxt.lineWidth = 3;
                cxt.lineJoin = "round";

                cxt.fill();
                cxt.stroke();

            cxt.restore()
        }

    
        function starPath(cxt){
        
            cxt.beginPath();
            for(var i=0;i<5;i++){
                cxt.lineTo(Math.cos( (18+i*72) / 180 * Math.PI )*20,
                                -Math.sin( (18+i*72) / 180 * Math.PI )*20);
                cxt.lineTo(Math.cos( (54+i*72) / 180 * Math.PI )*0.5*20,
                                -Math.sin( (54+i*72) / 180 * Math.PI )*0.5*20);
            }
            cxt.closePath();
        }
    </script>
</body>
<script>
    /*图形变换

        位移 translate(x,y)

        旋转 rotate(deg)

        缩放 scale(sx,sy)

    */
</script>
</html>

 

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