本文實(shí)例講述了JS實(shí)現(xiàn)基于Sketch.js模擬成群游動(dòng)的蝌蚪運(yùn)動(dòng)動(dòng)畫效果。分享給大家供大家參考，具體如下：
基于Sketch.js，實(shí)現(xiàn)了物體觸碰檢測（蝌蚪會(huì)遇到障礙物以及聰明的躲避鼠標(biāo)的點(diǎn)擊），隨機(jī)運(yùn)動(dòng)，聚集算法等。
已經(jīng)具備了游戲的基本要素，擴(kuò)展一下可以變成一個(gè)不錯(cuò)的 HTML5 游戲。
演示效果如下：
完整代碼如下：
<!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><div id="container"><canvas class="sketch" id="sketch-0" height="208" width="607"></canvas></div><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 = 'rgb(' + ~~random(0, 100) + ',' + ~~random(50, 220) + ',' + ~~random(50, 220) + ')'; //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 = 'rgb(' + ~~random(100, 250) + ',' + ~~random(10, 30) + ',' + ~~random(10, 30) + ')'; //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 = 'rgb(' + ~~random(130, 210) + ',' + ~~random(40, 140) + ',' + ~~random(160, 220) + ')'; //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('container')});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(['boid', 'predator', 'plant'], [1 - predatorProbability - plantProbability, predatorProbability, plantProbability])) { case 'predator': boid = new Predator(x, y); break; case 'plant': 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 = 'lighter'; for (i = boids.length - 1; i >= 0; i--) { boids[i].draw(sim); } sim.fillText(boids.length, 20, 20);};</script></body></html>附：完整實(shí)例代碼點(diǎn)擊此處本站下載。
更多關(guān)于JavaScript相關(guān)內(nèi)容感興趣的讀者可查看本站專題：《JavaScript動(dòng)畫特效與技巧匯總》、《JavaScript圖形繪制技巧總結(jié)》、《JavaScript切換特效與技巧總結(jié)》、《JavaScript錯(cuò)誤與調(diào)試技巧總結(jié)》、《JavaScript數(shù)據(jù)結(jié)構(gòu)與算法技巧總結(jié)》及《JavaScript數(shù)學(xué)運(yùn)算用法總結(jié)》
希望本文所述對(duì)大家JavaScript程序設(shè)計(jì)有所幫助。
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