JavaScript实现成群游动的蝌蚪动画效果-js教程-PHP中文网

这篇文章主要介绍了JS实现基于Sketch.js模拟成群游动的蝌蚪运动动画效果,涉及Sketch.js插件的使用及HTML5元素的应用技巧,并附带demo源码供读者下载参考,需要的朋友可以参考下
本文实例讲述了JS实现基于Sketch.js模拟成群游动的蝌蚪运动动画效果。分享给大家供大家参考，具体如下：
基于Sketch.js，实现了物体触碰检测（蝌蚪会遇到障碍物以及聪明的躲避鼠标的点击），随机运动，聚集算法等。
已经具备了游戏的基本要素，扩展一下可以变成一个不错的 HTML5 游戏。
演示效果如下：
完整代码如下：
<!DOCTYPE html>
<html class=" -webkit- js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths">
<head>
<meta charset="UTF-8">
<title>HTML5 Preview Panel</title>
<script src="prefixfree.min.js"></script>
<script src="modernizr.js"></script>
<style>
body {
  background-color: #222;
}
</style>
</head>
<body>
<script src="sketch.min.js"></script>
<p id="container">
<canvas class="sketch" id="sketch-0" height="208" width="607"></canvas>
</p>
<script>
var calculateDistance = function(object1, object2) {
  x = Math.abs(object1.x - object2.x);
  y = Math.abs(object1.y - object2.y);
  return Math.sqrt((x * x) + (y * y));
};
var calcMagnitude = function(x, y) {
  return Math.sqrt((x * x) + (y * y));
};
var calcVectorAdd = function(v1, v2) {
  return {
    x: v1.x + v2.x,
    y: v1.y + v2.y
  };
};
var random = function(min, max) {
  return min + Math.random() * (max - min);
};
var getRandomItem = function(list, weight) {
  var total_weight = weight.reduce(function(prev, cur, i, arr) {
    return prev + cur;
  });
  var random_num = random(0, total_weight);
  var weight_sum = 0;
  //console.log(random_num)
  for (var i = 0; i < list.length; i++) {
    weight_sum += weight[i];
    weight_sum = +weight_sum.toFixed(2);
    if (random_num <= weight_sum) {
      return list[i];
    }
  }
  // end of function
};
/***********************
BOID
***********************/
function Boid(x, y) {
  this.init(x, y);
}
Boid.prototype = {
  init: function(x, y) {
    //body
    this.type = "boid";
    this.alive = true;
    this.health = 1;
    this.maturity = 4;
    this.speed = 6;
    this.size = 5;
    this.hungerLimit = 12000;
    this.hunger = 0;
    this.isFull = false;
    this.digestTime = 400;
    this.color = &#39;rgb(&#39; + ~~random(0, 100) + &#39;,&#39; + ~~random(50, 220) + &#39;,&#39; + ~~random(50, 220) + &#39;)&#39;;
    //brains
    this.eyesight = 100; //range for object dectection
    this.personalSpace = 20; //distance to avoid safe objects
    this.flightDistance = 60; //distance to avoid scary objects
    this.flockDistance = 100; //factor that determines how attracted the boid is to the center of the flock
    this.matchVelFactor = 6; //factor that determines how much the flock velocity affects the boid. less = more matching
    this.x = x || 0.0;
    this.y = y || 0.0;
    this.v = {
      x: random(-1, 1),
      y: random(-1, 1),
      mag: 0
    };
    this.unitV = {
      x: 0,
      y: 0,
    };
    this.v.mag = calcMagnitude(this.v.x, this.v.y);
    this.unitV.x = (this.v.x / this.v.mag);
    this.unitV.y = (this.v.y / this.v.mag);
  },
  wallAvoid: function(ctx) {
    var wallPad = 10;
    if (this.x < wallPad) {
      this.v.x = this.speed;
    } else if (this.x > ctx.width - wallPad) {
      this.v.x = -this.speed;
    }
    if (this.y < wallPad) {
      this.v.y = this.speed;
    } else if (this.y > ctx.height - wallPad) {
      this.v.y = -this.speed;
    }
  },
  ai: function(boids, index, ctx) {
    percievedCenter = {
      x: 0,
      y: 0,
      count: 0
    };
    percievedVelocity = {
      x: 0,
      y: 0,
      count: 0
    };
    mousePredator = {
      x: ((typeof ctx.touches[0] === "undefined") ? 0 : ctx.touches[0].x),
      y: ((typeof ctx.touches[0] === "undefined") ? 0 : ctx.touches[0].y)
    };
    for (var i = 0; i < boids.length; i++) {
      if (i != index) {
        dist = calculateDistance(this, boids[i]);
        //Find all other boids close to it
        if (dist < this.eyesight) {
          //if the same species then flock
          if (boids[i].type == this.type) {
            //Alignment
            percievedCenter.x += boids[i].x;
            percievedCenter.y += boids[i].y;
            percievedCenter.count++;
            //Cohesion
            percievedVelocity.x += boids[i].v.x;
            percievedVelocity.y += boids[i].v.y;
            percievedVelocity.count++;
            //Separation
            if (dist < this.personalSpace + this.size + this.health) {
              this.avoidOrAttract("avoid", boids[i]);
            }
          } else {
            //if other species fight or flight
            if (dist < this.size + this.health + boids[i].size + boids[i].health) {
              this.eat(boids[i]);
            } else {
              this.handleOther(boids[i]);
            }
          }
        } //if close enough
      } //dont check itself
    } //Loop through boids
    //Get the average for all near boids
    if (percievedCenter.count > 0) {
      percievedCenter.x = ((percievedCenter.x / percievedCenter.count) - this.x) / this.flockDistance;
      percievedCenter.y = ((percievedCenter.y / percievedCenter.count) - this.y) / this.flockDistance;
      this.v = calcVectorAdd(this.v, percievedCenter);
    }
    if (percievedVelocity.count > 0) {
      percievedVelocity.x = ((percievedVelocity.x / percievedVelocity.count) - this.v.x) / this.matchVelFactor;
      percievedVelocity.y = ((percievedVelocity.y / percievedVelocity.count) - this.v.y) / this.matchVelFactor;
      this.v = calcVectorAdd(this.v, percievedVelocity);
    }
    //Avoid Mouse
    if (calculateDistance(mousePredator, this) < this.eyesight) {
      var mouseModifier = 20;
      this.avoidOrAttract("avoid", mousePredator, mouseModifier);
    }
    this.wallAvoid(ctx);
    this.limitVelocity();
  },
  setUnitVector: function() {
    var magnitude = calcMagnitude(this.v.x, this.v.y);
    this.v.x = this.v.x / magnitude;
    this.v.y = this.v.y / magnitude;
  },
  limitVelocity: function() {
    this.v.mag = calcMagnitude(this.v.x, this.v.y);
    this.unitV.x = (this.v.x / this.v.mag);
    this.unitV.y = (this.v.y / this.v.mag);
    if (this.v.mag > this.speed) {
      this.v.x = this.unitV.x * this.speed;
      this.v.y = this.unitV.y * this.speed;
    }
  },
  avoidOrAttract: function(action, other, modifier) {
    var newVector = {
      x: 0,
      y: 0
    };
    var direction = ((action === "avoid") ? -1 : 1);
    var vModifier = modifier || 1;
    newVector.x += ((other.x - this.x) * vModifier) * direction;
    newVector.y += ((other.y - this.y) * vModifier) * direction;
    this.v = calcVectorAdd(this.v, newVector);
  },
  move: function() {
    this.x += this.v.x;
    this.y += this.v.y;
    if (this.v.mag > this.speed) {
      this.hunger += this.speed;
    } else {
      this.hunger += this.v.mag;
    }
  },
  eat: function(other) {
    if (!this.isFull) {
      if (other.type === "plant") {
        other.health--;
        this.health++;
        this.isFull = true;
        this.hunger = 0;
      }
    }
  },
  handleOther: function(other) {
    if (other.type === "predator") {
      this.avoidOrAttract("avoid", other);
    }
  },
  metabolism: function() {
    if (this.hunger >= this.hungerLimit) {
      this.health--;
      this.hunger = 0;
    }
    if (this.hunger >= this.digestTime) {
      this.isFull = false;
    }
    if (this.health <= 0) {
      this.alive = false;
    }
  },
  mitosis: function(boids) {
    if (this.health >= this.maturity) {
      //reset old boid
      this.health = 1;
      birthedBoid = new Boid(
        this.x + random(-this.personalSpace, this.personalSpace),
        this.y + random(-this.personalSpace, this.personalSpace)
      );
      birthedBoid.color = this.color;
      boids.push(birthedBoid);
    }
  },
  draw: function(ctx) {
    drawSize = this.size + this.health;
    ctx.beginPath();
    ctx.moveTo(this.x + (this.unitV.x * drawSize), this.y + (this.unitV.y * drawSize));
    ctx.lineTo(this.x + (this.unitV.y * drawSize), this.y - (this.unitV.x * drawSize));
    ctx.lineTo(this.x - (this.unitV.x * drawSize * 2), this.y - (this.unitV.y * drawSize * 2));
    ctx.lineTo(this.x - (this.unitV.y * drawSize), this.y + (this.unitV.x * drawSize));
    ctx.lineTo(this.x + (this.unitV.x * drawSize), this.y + (this.unitV.y * drawSize));
    ctx.fillStyle = this.color;
    ctx.shadowBlur = 20;
    ctx.shadowColor = this.color;
    ctx.fill();
  }
};
Predator.prototype = new Boid();
Predator.prototype.constructor = Predator;
Predator.constructor = Boid.prototype.constructor;
function Predator(x, y) {
  this.init(x, y);
  this.type = "predator";
  //body
  this.maturity = 6;
  this.speed = 6;
  this.hungerLimit = 25000;
  this.color = &#39;rgb(&#39; + ~~random(100, 250) + &#39;,&#39; + ~~random(10, 30) + &#39;,&#39; + ~~random(10, 30) + &#39;)&#39;;
  //brains
  this.eyesight = 150;
  this.flockDistance = 300;
}
Predator.prototype.eat = function(other) {
  if (!this.isFull) {
    if (other.type === "boid") {
      other.health--;
      this.health++;
      this.isFull = true;
      this.hunger = 0;
    }
  }
};
Predator.prototype.handleOther = function(other) {
  if (other.type === "boid") {
    if (!this.isFull) {
      this.avoidOrAttract("attract", other);
    }
  }
};
Predator.prototype.mitosis = function(boids) {
  if (this.health >= this.maturity) {
    //reset old boid
    this.health = 1;
    birthedBoid = new Predator(
      this.x + random(-this.personalSpace, this.personalSpace),
      this.y + random(-this.personalSpace, this.personalSpace)
    );
    birthedBoid.color = this.color;
    boids.push(birthedBoid);
  }
};
Plant.prototype = new Boid();
Plant.prototype.constructor = Plant;
Plant.constructor = Boid.prototype.constructor;
function Plant(x, y) {
  this.init(x, y);
  this.type = "plant";
  //body
  this.speed = 0;
  this.size = 10;
  this.health = ~~random(1, 10);
  this.color = &#39;rgb(&#39; + ~~random(130, 210) + &#39;,&#39; + ~~random(40, 140) + &#39;,&#39; + ~~random(160, 220) + &#39;)&#39;;
  //brains
  this.eyesight = 0;
  this.flockDistance = 0;
  this.eyesight = 0; //range for object dectection
  this.personalSpace = 100; //distance to avoid safe objects
  this.flightDistance = 0; //distance to avoid scary objects
  this.flockDistance = 0; //factor that determines how attracted the boid is to the center of the flock
  this.matchVelFactor = 0; //factor that determines how much the flock velocity affects the boid
}
Plant.prototype.ai = function(boids, index, ctx) {};
Plant.prototype.move = function() {};
Plant.prototype.mitosis = function(boids) {
  var growProbability = 1,
    maxPlants = 40,
    plantCount = 0;
  for (m = boids.length - 1; m >= 0; m--) {
    if (boids[m].type === "plant") {
      plantCount++;
    }
  }
  if (plantCount <= maxPlants) {
    if (random(0, 100) <= growProbability) {
      birthedBoid = new Plant(
        this.x + random(-this.personalSpace, this.personalSpace),
        this.y + random(-this.personalSpace, this.personalSpace)
      );
      birthedBoid.color = this.color;
      boids.push(birthedBoid);
    }
  }
};
Plant.prototype.draw = function(ctx) {
  var drawSize = this.size + this.health;
  ctx.fillStyle = this.color;
  ctx.shadowBlur = 40;
  ctx.shadowColor = this.color;
  ctx.fillRect(this.x - drawSize, this.y + drawSize, drawSize, drawSize);
};
/***********************
SIM
***********************/
var boids = [];
var sim = Sketch.create({
  container: document.getElementById(&#39;container&#39;)
});
sim.setup = function() {
  for (i = 0; i < 50; i++) {
    x = random(0, sim.width);
    y = random(0, sim.height);
    sim.spawn(x, y);
  }
};
sim.spawn = function(x, y) {
  var predatorProbability = 0.1,
    plantProbability = 0.3;
  switch (getRandomItem([&#39;boid&#39;, &#39;predator&#39;, &#39;plant&#39;], [1 - predatorProbability - plantProbability, predatorProbability, plantProbability])) {
    case &#39;predator&#39;:
      boid = new Predator(x, y);
      break;
    case &#39;plant&#39;:
      boid = new Plant(x, y);
      break;
    default:
      boid = new Boid(x, y);
      break;
  }
  boids.push(boid);
};
sim.update = function() {
  for (i = boids.length - 1; i >= 0; i--) {
    if (boids[i].alive) {
      boids[i].ai(boids, i, sim);
      boids[i].move();
      boids[i].metabolism();
      boids[i].mitosis(boids);
    } else {
      //remove dead boid
      boids.splice(i, 1);
    }
  }
};
sim.draw = function() {
  sim.globalCompositeOperation = &#39;lighter&#39;;
  for (i = boids.length - 1; i >= 0; i--) {
    boids[i].draw(sim);
  }
  sim.fillText(boids.length, 20, 20);
};
</script>
</body>
</html>
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