JavaScript實現成群遊動的蝌蚪動畫效果-js教程-PHP中文網

這篇文章主要介紹了JS實現基於Sketch.js模擬成群遊動的蝌蚪運動動畫效果,涉及Sketch.js插件的使用及HTML5元素的應用技巧,並附帶demo源碼供讀者下載參考,需要的朋友可以參考下
本文實例講述了JS實現基於Sketch.js模擬成群遊動的蝌蚪運動動畫效果。分享給大家供大家參考，具體如下：
基於Sketch.js，實現了物體觸碰檢測（蝌蚪會遇到障礙物以及聰明的躲避滑鼠的點擊），隨機運動，聚集演算法等。
已經具備了遊戲的基本要素，擴充一下可以變成一個不錯的 HTML5 遊戲。
示範效果如下：
完整程式碼如下：
<!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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