游戏开发中伪随机正态分布JavaScript

在游戏开发中经常遇到随机奖励的情况，一般会采取先生成数组，再一个一个取的方式发随机奖励。

下面是js测试正态分布代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<canvas id="myCanvas" width="800" height="400" style="border:1px solid #c3c3c3;">
    Your browser does not support the canvas element.
</canvas>
<canvas id="myCanvas2" width="800" height="400" style="border:1px solid #c3c3c3;">
    Your browser does not support the canvas element.
</canvas>
<textarea id="text" cols="200" rows="5000"></textarea>
<script type="text/javascript">

    var timesArr = [];
    var timesArrObj = {};
    window.onload = function () {
//        for (var meter = 0; meter < 800; meter++) {
//            var times = getNumberInNormalDistribution(20, 7);
//            addPoint(times, meter);
//            timesArr.push(Math.floor(times));
//        }
//        drawGreenTab(timesArr,1);
        // drawLine(0, 380, 800, 380);
        drawResult(1);
        drawResult(2);
        drawResult(0);
        drawGreenTab(timesArrObj[1], 1);
        drawGreenTab(timesArrObj[2], 2);
        drawGreenTab(timesArrObj[0], 0);

    }
    //制作绿色柱状图表
    function drawGreenTab(timesArr, color) {
        var timesTypes = {};
        for (var i in timesArr) {
            var times = timesArr[i];
            if (timesTypes[times] == null) {
                timesTypes[times] = 0;
            } else {
                timesTypes[times] = timesTypes[times] + 1;
            }
        }
        for (var i in timesTypes) {
            drawRect(i, timesTypes[i], 4, color);
        }
    }
    //画圆点
    function addPoint(y, x, color) {
        y = 400 - y;
        var c = document.getElementById("myCanvas");
        var cxt = c.getContext("2d");
        if (color == null) {
            cxt.fillStyle = "#FF0000";
        } else {
            cxt.fillStyle = color;
        }
        cxt.beginPath();
        cxt.arc(x, y, 2, 0, Math.PI * 2, true);
        cxt.closePath();
        cxt.fill();
    }
    var meter = 0;
    //划线
    function drawLine(beginx, beginy, endx, endy) {
        var c = document.getElementById("myCanvas");
        var cxt = c.getContext("2d");
        cxt.moveTo(beginx, beginy);
        cxt.lineTo(endx, endy);
        cxt.stroke();
    }
    //模拟正态分布取值
    function getNumberInNormalDistribution(mean, std_dev) {
        return mean + (uniform2NormalDistribution() * std_dev);
    }
    //模拟正态分布偏差
    function uniform2NormalDistribution() {
        var sum = 0.0;
        for (var i = 0; i < 12; i++) {
            sum = sum + Math.random();
        }
        return sum - 6;
    }
    //画一个长方形
    function drawRect(x, y, width, index) {
        var color = "#FF0000";
        if (index == 1) {
            color = "#00FF00";
        } else if (index == 2) {
            color = "#0000FF";
        }
        var c = document.getElementById("myCanvas2");
        var cxt = c.getContext("2d");
        cxt.fillStyle = color;
        cxt.fillRect(x * width + index * 200, 400 - y, width - 2, y);
    }
    //画出生成的图像
    function drawResult(index) {
        var color = "#FF0000";
        if (index % 3 == 1) {
            color = "#00FF00";
        } else if (index % 3 == 2) {
            color = "#0000FF";
        }
        var result = generateList();
        var resultStr = "";
//        for (var i in result) {
//            resultStr = resultStr + result[i] + "\n";
//        }
        //document.getElementById("text").value = resultStr;
        var resulttimes = {};
        for (var i in result) {
            if (resulttimes[result[i]] == null) {
                resulttimes[result[i]] = 1;
            } else {
                resulttimes[result[i]] = resulttimes[result[i]] + 1;
            }
        }
        for (var i in resulttimes) {
            resultStr = resultStr + resulttimes[i] + "\n";
        }
        document.getElementById("text").value = resultStr;
        var timeslist = [];
        var times = 1;
        for (var i in result) {
            if (result[i] == index) {
                addPoint(times, i / 5, color);
                if (timesArrObj[index] == null) {
                    timesArrObj[index] = [];
                }
                timesArrObj[index].push(times);
                times = 0;
            } else {
                times++;
            }
        }
    }
    //权重数组
    var wt = [105, 216, 316, 488, 1000, 2000, 3680, 5890];//,14770,71535
    //生成结果数组函数，结果为权重数组的索引，从0开始
    function generateList() {
        //生成的结果数组长度
        var n = 50000;
        var wtp = [];
        var sum = 0;
        for (var i in wt) {
            sum = sum + wt[i];
        }
        for (var i in wt) {
            wtp.push(wt[i] / sum);
        }
        var result = [];
        var p = [];
        for (var i in wtp) {
            var inp = getNumberInNormalDistribution(1 / wtp[i], 1 / wtp[i] / 3);
            p.push(inp);
        }
        for (var i = 0; i < n; i++) {
            var minp = 99999999;
            var minj = -1;
            for (var j in p) {
                if (p[j] < minp) {
                    minp = p[j];
                    minj = j;
                }
            }
            result.push(minj);
            for (var j in p) {
                p[j] = p[j] - minp;
            }
            p[minj] = getNumberInNormalDistribution(1 / wtp[minj], 1 / wtp[minj] / 3);
        }
        return result;

    }
</script>
</body>
</html>

 

posted @ 2019-10-17 15:34  然然1907  阅读(558)  评论(0)  编辑  收藏  举报