---
categories: Repost
date: "2025-06-02T00:00:00Z"
tags:
    - 前端
    - 信息技术
    - Demo
slug: Donut-js
title: Donut in JavaScript
---

[Source](https://github.com/petercunha/Donut) [MIT License](https://github.com/petercunha/Donut/blob/master/LICENSE)

<pre class="center" id="d"></pre>

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    var pretag = document.getElementById("d");

    var tmr1 = undefined,
        tmr2 = undefined;
    var A = 1,
        B = 1;

    var asciiframe = () => {
        var b = [];
        var z = [];
        A += 0.07;
        B += 0.03;
        var cA = Math.cos(A),
            sA = Math.sin(A),
            cB = Math.cos(B),
            sB = Math.sin(B);
        for (var k = 0; k < 1760; k++) {
            b[k] = k % 80 == 79 ? "\n" : " ";
            z[k] = 0;
        }
        for (var j = 0; j < 6.28; j += 0.07) {
            // j <=> theta
            var ct = Math.cos(j),
                st = Math.sin(j);
            for (i = 0; i < 6.28; i += 0.02) {
                // i <=> phi
                var sp = Math.sin(i),
                    cp = Math.cos(i),
                    h = ct + 2, // R1 + R2*cos(theta)
                    D = 1 / (sp * h * sA + st * cA + 5), // this is 1/z
                    t = sp * h * cA - st * sA; // this is a clever factoring of some of the terms in x' and y'

                var x = 0 | (40 + 30 * D * (cp * h * cB - t * sB)),
                    y = 0 | (12 + 15 * D * (cp * h * sB + t * cB)),
                    o = x + 80 * y,
                    N =
                        0 |
                        (8 *
                            ((st * sA - sp * ct * cA) * cB -
                                sp * ct * sA -
                                st * cA -
                                cp * ct * sB));
                if (y < 22 && y >= 0 && x >= 0 && x < 79 && D > z[o]) {
                    z[o] = D;
                    b[o] = ".,-~:;=!*#$@"[N > 0 ? N : 0];
                }
            }
        }
        pretag.innerHTML = b.join("");
    };

    setInterval(asciiframe, 50);
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