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    HTML5 canvas如何绘制酷炫能量线条效果(附代码)

    奋力向前奋力向前2021-07-13 18:39:25转载151
    本篇文章给大家介绍一下使用HTML5 canvas绘制酷炫能量线条特效的方法。有一定的参考价值,有需要的朋友可以参考一下,希望对你们有所助。

    在这里插入图片描述

    上面是效果图,下面直接附js代码,希望对大家有所帮助!!

    // UTILconst PI = Math.PI,
      TWO_PI = Math.PI * 2;const Util = {};Util.timeStamp = function() {
      return window.performance.now();};Util.random = function(min, max) {
      return min + Math.random() * (max - min);};Util.map = function(a, b, c, d, e) {
      return (a - b) / (c - b) * (e - d) + d;};Util.lerp = function(value1, value2, amount) {
      return value1 + (value2 - value1) * amount;};Util.clamp = function(value, min, max) {
      return Math.max(min, Math.min(max, value));};// Vectorclass Vector {
      constructor(x, y) {
        this.x = x || 0;
        this.y = y || 0;
      }
      set(x, y) {
        this.x = x;
        this.y = y;
      }
      reset() {
        this.x = 0;
        this.y = 0;
      }
      fromAngle(angle) {
        let x = Math.cos(angle),
          y = Math.sin(angle);
        return new Vector(x, y);
      }
      add(vector) {
        this.x += vector.x;
        this.y += vector.y;
      }
      sub(vector) {
        this.x -= vector.x;
        this.y -= vector.y;
      }
      mult(scalar) {
        this.x *= scalar;
        this.y *= scalar;
      }
      p(scalar) {
        this.x /= scalar;
        this.y /= scalar;
      }
      dot(vector) {
        return vector.x * this.x + vector.y * this.y;
      }
      limit(limit_value) {
        if (this.mag() > limit_value) this.setMag(limit_value);
      }
      mag() {
        return Math.hypot(this.x, this.y);
      }
      setMag(new_mag) {
        if (this.mag() > 0) {
          this.normalize();
        } else {
          this.x = 1;
          this.y = 0;
        }
        this.mult(new_mag);
      }
      normalize() {
        let mag = this.mag();
        if (mag > 0) {
          this.x /= mag;
          this.y /= mag;
        }
      }
      heading() {
        return Math.atan2(this.y, this.x);
      }
      setHeading(angle) {
        let mag = this.mag();
        this.x = Math.cos(angle) * mag;
        this.y = Math.sin(angle) * mag;
      }
      dist(vector) {
        return new Vector(this.x - vector.x, this.y - vector.y).mag();
      }
      angle(vector) {
        return Math.atan2(vector.y - this.y, vector.x - this.x);
      }
      copy() {
        return new Vector(this.x, this.y);
      }}// Init canvaslet canvas = document.createElement("canvas"),
      ctx = canvas.getContext("2d"),
      H = (canvas.height = window.innerHeight),
      W = (canvas.width = window.innerWidth);document.body.appendChild(canvas);// Mouselet mouse = {
      x: W/2,
      y: H/2};canvas.onmousemove = function(event) {
      mouse.x = event.clientX - canvas.offsetLeft;
      mouse.y = event.clientY - canvas.offsetTop;};document.body.onresize = function(event){
      H = (canvas.height = window.innerHeight);
      W = (canvas.width = window.innerWidth);}// Let's goclass Arrow {
      constructor(x, y, target) {
        this.position = new Vector(x, y);
        this.velocity = new Vector().fromAngle(Util.random(0,TWO_PI));
        this.acceleration = new Vector(0, 0);
        this.target = target;
        this.travelled_distance = 0;
        this.min_size = 1;
        this.max_size = 6;
        this.size = Util.random(this.min_size, this.max_size);
        this.zone = this.size * 4;
        this.topSpeed = Util.map(this.size,this.min_size,this.max_size,40,10);
        let tailLength = Math.floor(Util.map(this.size, this.min_size, this.max_size, 4, 16));
        this.tail = [];
        for (let i = 0; i < tailLength; i++) {
          this.tail.push({
            x: this.position.x,
            y: this.position.y      });
        }
        this.wiggle_speed = Util.map(this.size, this.min_size, this.max_size, 2 , 1.2);
        this.blink_offset = Util.random(0, 100);
        this.alpha = Util.random(0.1,1)
      }
      render() {
        this.update();
        this.draw();
      }
      update() {
        let old_position = this.position.copy();
        // Focus on target
        let t = new Vector(this.target.x, this.target.y),
          angle = this.position.angle(t);
        let d_f_target = t.dist(this.position);
          let f = new Vector().fromAngle(angle);
    
          f.setMag(Util.map(Util.clamp(d_f_target,0,400), 0, 400, 0, this.topSpeed * 0.1));
          this.addForce(f);
        
        // Update position and velocity
        this.velocity.add(this.acceleration);
        if(d_f_target < 800){
           this.velocity.limit(Util.map(Util.clamp(d_f_target,0,800), 0, 800, this.topSpeed*0.4, this.topSpeed));
           }else{
             this.velocity.limit(this.topSpeed);
           }
        this.position.add(this.velocity);
        // Reset acceleration for the next loop
        this.acceleration.mult(0);
        this.travelled_distance += old_position.dist(this.position);
    
          let wiggle =
            Math.sin(frame * this.wiggle_speed) *
            Util.map(this.velocity.mag(), 0, this.topSpeed, 0, this.size);
          let w_a = this.velocity.heading() + Math.PI / 2;
    
          let w_x = this.position.x + Math.cos(w_a) * wiggle,
            w_y = this.position.y + Math.sin(w_a) * wiggle;
    
          this.travelled_distance = 0;
          let from = this.tail.length - 1,
            to = 0;
              let n = new Vector().fromAngle(Util.random(0,TWO_PI));
          n.setMag(Math.random()*this.size);
    
        
          var tail = { x: w_x+ n.x, y: w_y + n.y};
          this.tail.splice(from, 1);
          this.tail.splice(to, 0, tail);
        
      }
      draw() {
        
            let energy = Util.map(this.velocity.mag(),0,this.topSpeed,0.1,1);
    
        
        let color =
          "hsl("+Math.sin((frame + this.blink_offset) * 0.1) * 360+",50%,"+
            
            Util.map(this.velocity.mag(),0,this.topSpeed,40,100) * this.alpha    
        +"%)";
        ctx.globalAlpha = this.alpha;
    
        ctx.strokeStyle = color;
        for (let i = 0; i < this.tail.length - 1; i++) {
          let t = this.tail[i],
            next_t = this.tail[i + 1];
          ctx.lineWidth = Util.map(i, 0, this.tail.length - 1, this.size, 1);
          ctx.beginPath();
          ctx.moveTo(t.x, t.y);
          ctx.lineTo(next_t.x, next_t.y);
          ctx.closePath();
          ctx.stroke();
        }
        
        let gradient_size = 140 * energy;var grd = ctx.createRadialGradient(
      this.position.x,this.position.y , 5,
      this.position.x,this.position.y, gradient_size);grd.addColorStop(0, "rgba(255,255,255,0.01)");grd.addColorStop(0.1, "rgba(255,120,200,0.02)");grd.addColorStop(0.9, "rgba(255,255,120,0)");grd.addColorStop(1, "rgba(0,0,0,0)");// Fill with gradientctx.fillStyle = grd;ctx.fillRect(this.position.x - gradient_size / 2 ,this.position.y - gradient_size / 2 , gradient_size, gradient_size); 
        
        ctx.globalAlpha = energy+0.2;
        ctx.fillStyle = "white";
        for(let i = 0; i < 4; i++){
          let n = new Vector().fromAngle(Util.random(0,TWO_PI));
          n.setMag(Math.random()*energy*100);
          n.add(this.position);
          ctx.beginPath();
          ctx.arc(n.x,n.y,Math.random(),0,TWO_PI)
          ctx.fill();
        }
        
      }
      addForce(vector) {
        this.acceleration.add(vector);
      }
      avoid(others) {
        others.forEach(other => {
          if (other !== this) {
            let dist = this.position.dist(other.position),
              max_dist = this.zone + other.size;
            if (max_dist - dist >= 0) {
              let angle = other.position.angle(this.position);
              let force = new Vector().fromAngle(angle);
              force.setMag(Util.map(dist, 0, max_dist, 2, 0));
              this.addForce(force);
            }
          }
        });
      }}let arrows = [];for (let i = 0; i < 100; i++) {
      arrows.push(new Arrow(W / 2, H / 2, mouse));}let frame = 0;ctx.strokeStyle = "white";function loop() {
      ctx.fillStyle="black";
      ctx.globalCompositeOperation = "source-over";
      ctx.globalAlpha = 0.2;
      ctx.fillRect(0, 0, W, H);
      ctx.globalAlpha = 1;
      ctx.globalCompositeOperation = "lighter";
      arrows.forEach(a => {
        a.avoid(arrows);
      });
      arrows.forEach(a => {
        a.render();
      });
      frame += 1;
      requestAnimationFrame(loop);}ctx.lineCap = "round";ctx.lineJoin = "round";loop();

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