node-pureimage/polytest1.html at master · OluTech/node-pureimage · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style type="text/css">
        .fill {
            padding:0;
            margin: 0;
            background-color: black;
            display: flex;
            align-content: center;
            align-items: center;
            justify-content: center;
            border: 0px solid blue;
            position: absolute;
            top:0;
            bottom: 0;
            left:0;
            right:0;
        }

    </style>
</head>
<body>

<div class="fill">
<canvas id='canvas' width="1000" height="600"></canvas>
    </div>

<script type="application/javascript">


    function rand(min,max) {
        return min + Math.random()*(max-min);
    }

    /**
     * Converts an HSV color value to RGB. Conversion formula
     * adapted from http://en.wikipedia.org/wiki/HSV_color_space.
     * Assumes h, s, and v are contained in the set [0, 1] and
     * returns r, g, and b in the set [0, 255].
     *
     * @param   Number  h       The hue
     * @param   Number  s       The saturation
     * @param   Number  v       The value
     * @return  Array           The RGB representation
     */
    function hsvToRgb(h, s, v){
        var r, g, b;

        var i = Math.floor(h * 6);
        var f = h * 6 - i;
        var p = v * (1 - s);
        var q = v * (1 - f * s);
        var t = v * (1 - (1 - f) * s);

        switch(i % 6){
            case 0: r = v, g = t, b = p; break;
            case 1: r = q, g = v, b = p; break;
            case 2: r = p, g = v, b = t; break;
            case 3: r = p, g = q, b = v; break;
            case 4: r = t, g = p, b = v; break;
            case 5: r = v, g = p, b = q; break;
        }

        return [r * 255, g * 255, b * 255];
    }

    function pick(arr) {
        return arr[Math.floor(Math.random()*arr.length)];
    }


    var canvas = document.getElementById("canvas");
    function draw() {
        var ctx = canvas.getContext('2d');
        var w = canvas.width;
        var h = canvas.height;
        var gw = Math.floor(w/43);
        var gh = Math.floor(h/43);
        ctx.fillStyle = 'black';
        ctx.fillRect(0,0,w,h);

        var grid = [];
        for(var j=0; j<gh; j++) {
            for(var i=0; i<gw; i++) {
                grid.push({x:40+i*40, y:40+j*40});
            }
        }
        function xy(x,y) {
            return grid[y*gw+x];
        }

        var colors = [];
        for(var s=0.2; s<1; s+=0.1) {
            colors.push(hsvToRgb(1.0, 1.0, s));
        }

        var cells = [];
        for(var i=0; i<gw-1; i++) {
            for(var j=0; j<gh-1; j++) {
                var pt1 = xy(i,j);
                var pt2 = xy(i+1,j);
                var pt3 = xy(i+1,j+1);
                var pt4 = xy(i,j+1);
                var color = colors[i%6];//pick(colors);
                //var color = pick(colors);
                cells.push([pt1,pt2,pt3,pt4, color]);
            }
        }

        //randomly shift the grid
        grid.forEach(function(pt){
            var dist = 19;
            pt.x = pt.x + rand(-dist,dist);
            pt.y = pt.y + rand(-dist,dist);
        });

        //draw the dots
        ctx.fillStyle = 'white';
        grid.forEach(function(pt){
//            ctx.fillRect(pt.x,pt.y, 4, 4)
        });

        //fill the polys
        cells.forEach(function(cell) {
            ctx.fillStyle = 'green';
            ctx.beginPath();
            ctx.moveTo(cell[0].x, cell[0].y);
            ctx.lineTo(cell[1].x, cell[1].y);
            ctx.lineTo(cell[2].x, cell[2].y);
            ctx.lineTo(cell[3].x, cell[3].y);
            ctx.closePath();
            var c = cell[4];
            var color = 'rgb('+Math.floor(c[0])+','+Math.floor(c[1])+','+Math.floor(c[2])+')';
            ctx.fillStyle = color;
            ctx.fill();
        });
        cells.forEach(function(cell) {
            ctx.strokeStyle = 'black';
            ctx.beginPath();
            ctx.moveTo(cell[0].x, cell[0].y);
            ctx.lineTo(cell[1].x, cell[1].y);
            ctx.lineTo(cell[2].x, cell[2].y);
            ctx.lineTo(cell[3].x, cell[3].y);
            ctx.closePath();
            ctx.stroke();
        });
    }
    draw();

</script>

</body>
</html>