canvas 烟花特效

旧城等待， 2022-05-31 01:26 159阅读 0赞

特效代码，本特效来自脚本之家，我将其去除了jQuery，还有一些其他的更改

<!DOCTYPE HTML>
    <html>
    
    <head>
      <title>Canvas 实现放烟花特效</title>
      <meta charset="utf-8">
      <meta http-equiv="X-UA-Compatible" content="IE=edge">
      <style type="text/css">
        body {
          background: #ccc;
        }
    
        #banner-fire { 
          position: relative;
        }
    
        #banner-fire img { 
          width: 100%;
          max-width: 1920px;
          margin: 0 auto;
        }
    
        canvas {
          position: absolute;
          z-index: 9;
          top: 0;
          left: 0;
          width: 100%;
          max-width: 1920px;
          display: block;
          will-change: auto;
        }
      </style>
    </head>
    
    <body>
      <div id="banner-fire">
        <img src="http://www.runyuanzs.com/templets/default/images/banner_750.png" alt="">
        <canvas id="canvas-fire"></canvas>
      </div>
      
      <script>
        document.getElementById('banner-fire').getElementsByTagName('img')[0].onload=function () { 
          /** * el String 被附着的元素 (只支持id) * canvas String canvas元素（只支持id） */
          // 产生烟花随机数 
          function rand(rMi, rMa) { 
            //按位取反运算符 
            return ~~((Math.random() * (rMa - rMi + 1)) + rMi);
          }
          var Fireworks = function (params) { 
            var self = this;
            var hitTest = function (x1, y1, w1, h1, x2, y2, w2, h2) { 
                return !(x1 + w1 < x2 || x2 + w2 < x1 || y1 + h1 < y2 || y2 + h2 < y1);
              };
            //请求动画帧 
            window.requestAnimFrame = function () { 
              return window.requestAnimationFrame ||
                window.webkitRequestAnimationFrame ||
                window.mozRequestAnimationFrame ||
                window.oRequestAnimationFrame ||
                window.msRequestAnimationFrame ||
                function (callback) { 
                  window.setTimeout(callback, 1000 / 60);
                }
            }();
            self.init = function () { 
              self.canvas = document.getElementById(params.canvas);
              self.attachEl = document.getElementById(params.el);
              //canvas 全屏 
              self.canvas.width = self.cw = self.attachEl.offsetWidth || document.body.offsetWidth;
              self.canvas.height = self.ch = self.attachEl.offsetHeight || document.body.offsetHeight;
              self.particles = [];
              self.partCount = 150;
              self.fireworks = [];
              self.mx = self.cw / 2;
              self.my = self.ch / 2;
              self.currentHue = 30;
              self.partSpeed = 5;
              self.partSpeedVariance = 10;
              self.partWind = 50;
              self.partFriction = 5;
              self.partGravity = 1;
              self.hueMin = 0;
              self.hueMax = 360;
              self.fworkSpeed = 4;
              self.fworkAccel = 10;
              self.hueVariance = 30;
              self.flickerDensity = 25;
              self.showShockwave = true;
              self.showTarget = false;
              self.clearAlpha = 25;
              self.ctx = self.canvas.getContext('2d');
              self.ctx.lineCap = 'round';
              self.ctx.lineJoin = 'round';
              self.lineWidth = 1;
              self.bindEvents();
              self.canvasLoop();
              self.canvas.onselectstart = function () { 
                return false;
              };
            };
            // 创建粒子 
            self.createParticles = function (x, y, hue) { 
              var countdown = self.partCount;
              while (countdown--) {
                var newParticle = {
                  x: x,
                  y: y,
                  coordLast: [{
                      x: x,
                      y: y
                    },
                    {
                      x: x,
                      y: y
                    },
                    {
                      x: x,
                      y: y
                    }
                  ],
                  angle: rand(0, 360),
                  speed: rand(((self.partSpeed - self.partSpeedVariance) <= 0) ? 1 : self.partSpeed - self.partSpeedVariance,
                    (self.partSpeed + self.partSpeedVariance)),
                  friction: 1 - self.partFriction / 100,
                  gravity: self.partGravity / 2,
                  hue: rand(hue - self.hueVariance, hue + self.hueVariance),
                  brightness: rand(50, 80),
                  alpha: rand(40, 100) / 100,
                  decay: rand(10, 50) / 1000,
                  wind: (rand(0, self.partWind) - (self.partWind / 2)) / 25,
                  lineWidth: self.lineWidth
                };
                self.particles.push(newParticle);
              }
            };
            // 更新粒子 
            self.updateParticles = function () { 
              var i = self.particles.length;
              while (i--) {
                var p = self.particles[i];
                var radians = p.angle * Math.PI / 180;
                var vx = Math.cos(radians) * p.speed;
                var vy = Math.sin(radians) * p.speed;
                p.speed *= p.friction;
                p.coordLast[2].x = p.coordLast[1].x;
                p.coordLast[2].y = p.coordLast[1].y;
                p.coordLast[1].x = p.coordLast[0].x;
                p.coordLast[1].y = p.coordLast[0].y;
                p.coordLast[0].x = p.x;
                p.coordLast[0].y = p.y;
                p.x += vx;
                p.y += vy;
                p.y += p.gravity;
                p.angle += p.wind;
                p.alpha -= p.decay;
                if (!hitTest(0, 0, self.cw, self.ch, p.x - p.radius, p.y - p.radius, p.radius * 2, p.radius * 2) ||
                  p.alpha < .05) {
                  self.particles.splice(i, 1);
                }
              };
            };
            // 绘制粒子 
            self.drawParticles = function () { 
              var i = self.particles.length;
              while (i--) {
                var p = self.particles[i];
                var coordRand = (rand(1, 3) - 1);
                self.ctx.beginPath();
                self.ctx.moveTo(Math.round(p.coordLast[coordRand].x), Math.round(p.coordLast[coordRand].y));
                self.ctx.lineTo(Math.round(p.x), Math.round(p.y));
                self.ctx.closePath();
                self.ctx.strokeStyle = 'hsla(' + p.hue + ', 100%, ' + p.brightness + '%, ' + p.alpha + ')';
                self.ctx.stroke();
                if (self.flickerDensity > 0) {
                  var inverseDensity = 50 - self.flickerDensity;
                  if (rand(0, inverseDensity) === inverseDensity) {
                    self.ctx.beginPath();
                    self.ctx.arc(Math.round(p.x), Math.round(p.y), rand(p.lineWidth, p.lineWidth + 3) / 2, 0, Math.PI *
                      2, false)
                    self.ctx.closePath();
                    var randAlpha = rand(50, 100) / 100;
                    self.ctx.fillStyle = 'hsla(' + p.hue + ', 100%, ' + p.brightness + '%, ' + randAlpha + ')';
                    self.ctx.fill();
                  }
                }
              };
            };
            // 创建烟花 
            self.createFireworks = function (startX, startY, targetX, targetY) { 
              var newFirework = {
                x: startX,
                y: startY,
                startX: startX,
                startY: startY,
                hitX: false,
                hitY: false,
                coordLast: [{
                    x: startX,
                    y: startY
                  },
                  {
                    x: startX,
                    y: startY
                  },
                  {
                    x: startX,
                    y: startY
                  }
                ],
                targetX: targetX,
                targetY: targetY,
                speed: self.fworkSpeed,
                angle: Math.atan2(targetY - startY, targetX - startX),
                shockwaveAngle: Math.atan2(targetY - startY, targetX - startX) + (90 * (Math.PI / 180)),
                acceleration: self.fworkAccel / 100,
                hue: self.currentHue,
                brightness: rand(50, 80),
                alpha: rand(50, 100) / 100,
                lineWidth: self.lineWidth
              };
              self.fireworks.push(newFirework);
            };
            // 更新烟花 
            self.updateFireworks = function () { 
              var i = self.fireworks.length;
              while (i--) {
                var f = self.fireworks[i];
                self.ctx.lineWidth = f.lineWidth;
                vx = Math.cos(f.angle) * f.speed,
                  vy = Math.sin(f.angle) * f.speed;
                f.speed *= 1 + f.acceleration;
                f.coordLast[2].x = f.coordLast[1].x;
                f.coordLast[2].y = f.coordLast[1].y;
                f.coordLast[1].x = f.coordLast[0].x;
                f.coordLast[1].y = f.coordLast[0].y;
                f.coordLast[0].x = f.x;
                f.coordLast[0].y = f.y;
                if (f.startX >= f.targetX) {
                  if (f.x + vx <= f.targetX) {
                    f.x = f.targetX;
                    f.hitX = true;
                  } else {
                    f.x += vx;
                  }
                } else {
                  if (f.x + vx >= f.targetX) {
                    f.x = f.targetX;
                    f.hitX = true;
                  } else {
                    f.x += vx;
                  }
                }
                if (f.startY >= f.targetY) {
                  if (f.y + vy <= f.targetY) {
                    f.y = f.targetY;
                    f.hitY = true;
                  } else {
                    f.y += vy;
                  }
                } else {
                  if (f.y + vy >= f.targetY) {
                    f.y = f.targetY;
                    f.hitY = true;
                  } else {
                    f.y += vy;
                  }
                }
                if (f.hitX && f.hitY) {
                  self.createParticles(f.targetX, f.targetY, f.hue);
                  self.fireworks.splice(i, 1);
                }
              };
            };
            // 绘制烟花 
            self.drawFireworks = function () { 
              var i = self.fireworks.length;
              self.ctx.globalCompositeOperation = 'lighter';
              while (i--) {
                var f = self.fireworks[i];
                self.ctx.lineWidth = f.lineWidth;
                var coordRand = (rand(1, 3) - 1);
                self.ctx.beginPath();
                self.ctx.moveTo(Math.round(f.coordLast[coordRand].x), Math.round(f.coordLast[coordRand].y));
                self.ctx.lineTo(Math.round(f.x), Math.round(f.y));
                self.ctx.closePath();
                self.ctx.strokeStyle = 'hsla(' + f.hue + ', 100%, ' + f.brightness + '%, ' + f.alpha + ')';
                self.ctx.stroke();
                if (self.showTarget) {
                  self.ctx.save();
                  self.ctx.beginPath();
                  self.ctx.arc(Math.round(f.targetX), Math.round(f.targetY), rand(1, 8), 0, Math.PI * 2, false)
                  self.ctx.closePath();
                  self.ctx.lineWidth = 1;
                  self.ctx.stroke();
                  self.ctx.restore();
                }
                if (self.showShockwave) {
                  self.ctx.save();
                  self.ctx.translate(Math.round(f.x), Math.round(f.y));
                  self.ctx.rotate(f.shockwaveAngle);
                  self.ctx.beginPath();
                  self.ctx.arc(0, 0, 1 * (f.speed / 5), 0, Math.PI, true);
                  self.ctx.strokeStyle = 'hsla(' + f.hue + ', 100%, ' + f.brightness + '%, ' + rand(25, 60) / 100 +
                    ')';
                  self.ctx.lineWidth = f.lineWidth;
                  self.ctx.stroke();
                  self.ctx.restore();
                }
              };
            };
            // 绑定事件 
            self.bindEvents = function () { 
              addEvent(window, 'resize', function () { 
                clearTimeout(self.timeout);
                self.timeout = setTimeout(function () { 
                  self.canvas.width = self.cw = document.getElementById(params.el).offsetWidth || document.body
                    .offsetWidth;
                  self.canvas.height = self.ch = document.getElementById(params.el).offsetHeight ||
                    document.body.offsetHeight;
                  self.ctx.lineCap = 'round';
                  self.ctx.lineJoin = 'round';
                }, 100);
              })
              addEvent(self.canvas, 'mouseover', function () { 
                addEvent(self.canvas, 'mousedown', function canvasDown(e) { 
                  self.mx = e.pageX - self.canvas.offsetLeft;
                  self.my = e.pageY - self.canvas.offsetTop;
                  self.currentHue = rand(self.hueMin, self.hueMax);
                  self.createFireworks(self.cw / 2, self.ch, self.mx, self.my);
                  addEvent(self.canvas, 'mousemove',canvasMouseMove )
                });
              })
              function canvasMouseMove(e) { 
                self.mx = e.pageX - self.canvas.offsetLeft;
                self.my = e.pageY - self.canvas.offsetTop;
                self.currentHue = rand(self.hueMin, self.hueMax);
                self.createFireworks(self.cw / 2, self.ch, self.mx, self.my);
              }
              addEvent(self.canvas, 'mouseup', function (e) { 
                removeEvent(self.canvas,'mousemove',canvasMouseMove);
              })
            };
            self.clear = function () { 
              self.particles = [];
              self.fireworks = [];
              self.ctx.clearRect(0, 0, self.cw, self.ch);
            };
            self.canvasLoop = function () { 
              requestAnimFrame(self.canvasLoop, self.canvas);
              self.ctx.globalCompositeOperation = 'destination-out';
              self.ctx.fillStyle = 'rgba(0,0,0,' + self.clearAlpha / 100 + ')';
              self.ctx.fillRect(0, 0, self.cw, self.ch);
              self.updateFireworks();
              self.updateParticles();
              self.drawFireworks();
              self.drawParticles();
            };
            setInterval(function () { 
              self.mx = rand(0,self.cw) - self.canvas.offsetLeft;
              self.my = rand(0,self.ch) - self.canvas.offsetTop;
              self.currentHue = rand(self.hueMin, self.hueMax);
              self.createFireworks(self.cw / 2, self.ch, self.mx, self.my);
            }, 1000);
            self.init();
          }
          var fworks = new Fireworks({
            el: 'banner-fire',
            canvas: 'canvas-fire'
          });
        };
        //添加事件监听
        function addEvent(obj, type, fn) { 
          if (obj.attachEvent) { //ie
            obj.attachEvent('on' + type, function () { 
              fn.call(obj);
            })
          } else {
            obj.addEventListener(type, fn, false);
          }
        }
        //移除事件监听
        function removeEvent(obj, type, fn) { 
          if (obj.detachEvent) { //ie
            obj.detachEvent('on' + type, function () { 
              fn.call(obj);
            })
          } else {
            obj.removeEventListener(type, fn, false);
          }
        }
      </script>
    </body>
    
    </html>