我是新來的HTML5畫布,我試圖使用圖層。我一直在尋找實現它們的方法,但沒有任何幫助我嘗試去做的事情。我正在嘗試製作火山爆發的動畫。我想把火山和背景天藍色放在一層,熔岩從天空落到第二層,灰雲在第三層。當我發現關於圖層的事情時,我已經做了這個工作,所以我知道事情不合適。我的問題是,我是否正在實施這些圖層的正確方向?初學者在HTML5畫布,使用圖層?
<body>
<div id="canvasesdiv" style="position:relative; width:400px; height:300px">
<canvas id="layer1" style="z-index: 1; position:absolute; left:0px; top:0px;" width="800" height="500"></canvas>
<canvas id="layer2" style="z-index: 2; position:absolute; left:0px; top:0px;" width="800" height="500"></canvas>
<canvas id="layer3" style="z-index: 3; position:absolute; left:0px; top:0px;" width="800" height="500"></canvas>
</div>
</body>
<script>
//var canvas = document.getElementById("myCanvas");
//var context = canvas.getContext("2d");
var layer1;
var layer2;
var layer3;
var particles;
var eruption;
var timer;
var timerRestart;
function init(){
layer1 = document.getElementById("layer1");
ctx1 = layer1.getContext("2d");
layer2 = document.getElementById("layer2");
ctx2 = layer2.getContext("2d");
layer3 = document.getElementById("layer3");
ctx3 = layer3.getContext("2d");
}
function animationHandler(){
fillBackgroundColor(canvas, context);
drawVolcano();
drawClouds();
eruption = setTimeout(makeParticles, 10);
}
function drawClouds(){
ctx3.beginPath();
ctx3.moveTo(0, 100);
ctx3.bezierCurveTo(0, 100, 75, 200, 150, 100);
ctx3.bezierCurveTo(150, 100, 225, 200, 300, 85);
ctx3.bezierCurveTo(300, 85, 375, 200, 450, 75);
ctx3.bezierCurveTo(450, 75, 525, 200, 600, 100);
ctx3.bezierCurveTo(600, 100, 700, 200, 800, 100);
ctx3.lineTo(800, 0);
ctx3.lineTo(0, 0);
ctx3.closePath();
ctx3.fillStyle = "#6f2a2a";
ctx3.fill();
ctx3.lineWidth = 5;
ctx3.strokeStyle = "#371515";
ctx3.stroke();
}
function drawVolcano(){
ctx1.beginPath();
ctx1.moveTo(0, 400);
ctx1.bezierCurveTo(0, 400, 250, 400, 325, 200);
ctx1.lineTo(425, 200);
ctx1.bezierCurveTo(425, 200, 450, 400, 800, 400);
ctx1.lineTo(800, 500);
ctx1.lineTo(0, 500);
ctx1.closePath();
ctx1.fillStyle = "#802b00";
ctx1t.fill();
ctx1.lineWidth = 5;
ctx1.strokeStyle = "#b33c00";
ctx1.stroke();
}
function fillBackgroundColor(canvas, context){
ctx1.fillStyle = "#3399ff" ;
ctx1.fillRect(0, 0, canvas.width, canvas.height);
}
function makeParticles() {
//create an array of particles for our animation
particles = [];
for(var i = 0; i < 100; i++)
{
particles.push(new Particle());
}
}
function degreesToRadians(degrees) {
//converts from degrees to radians and returns
return (degrees * Math.PI)/180;
}
function Particle(){
//the constructor for a single particle, with random starting x+y, velocity, color, and radius
//this.x = Math.random()*canvas.width;
//this.y = Math.random()*canvas.height;
this.x = canvas.width/2;
this.y = (0,0);
this.vx = Math.random()*16-8;
this.vy = Math.random()*10;
var colors = ["red", "#ff6600", "yellow", "#262626"];
this.color = colors[Math.floor(Math.random()*colors.length)];
this.radius = 50;
}
function moveParticles() {
//partially clear the screen to fade previous circles, and draw a new particle at each new coordinate
ctx2.globalCompositeOperation = "source-over";
ctx2.fillStyle = "rgba(0, 0, 0, 0.3)";
ctx2.fillRect(0, 0, canvas.width, canvas.height);
ctx2.globalCompositeOperation = "lighter";
for(var i = 0; i < particles.length; i++)
{
var p = particles[i];
ctx2.beginPath();
ctx2.arc(p.x, p.y, p.radius, 0, degreesToRadians(360), true);
ctx2.fillStyle = p.color;
ctx2.fill();
p.x += p.vx;
p.y += p.vy;
if(p.x < -50) p.x = canvas.width+50;
if(p.y < -50) p.y = canvas.height+50;
if(p.x > canvas.width+50) p.x = -50;
if(p.y > canvas.height+50) p.y = -50;
p.radius -= 1;
}
}
function clearScreen(color) {
//clears the screen and fills with the color of choice
ctx2.clearRect(0, 0, canvas.width, canvas.height);
ctx2.fillStyle = color;
ctx2.fillRect(0, 0, canvas.width, canvas.height);
}
window.onload = function() {
animationHandler();
timer = setInterval(moveParticles, 60);
//timerRestart = setInterval(makeParticles, 4000);
}
編輯:所以我的問題之前,爲什麼我就開始嘗試使用層是由於熔岩的動畫會黑掉在畫布上。所以我想如果我把所有東西都分離到不同的層次上,它不會使畫布黑屏。我在答案中實施了塞爾吉奧的代碼,這與我試圖達到的目標接近,但我仍然從之前就得到了這個問題。我引用了一些爆發動畫的代碼,這就是動畫本身的作用。我想我應該把這個問題放到一個單獨的問題中,但是有沒有什麼方法可以讓熔岩運行到與現在一樣效果的地方,但是也許到了它的畫布「不透明度下降到可以看到的位置下面的圖層? 這是動畫發生的地方:
function moveParticles() {
//partially clear the screen to fade previous circles, and draw a new particle at each new coordinate
ctx2.globalCompositeOperation = "source-over";
ctx2.fillStyle = "rgba(0, 0, 0, 0.3)";
ctx2.fillRect(0, 0, canvas.width, canvas.height);
ctx2.globalCompositeOperation = "lighter";
這是很多調試!有沒有特別的東西沒有用? – Noah
您還沒有真正問過問題......請解釋您的代碼現在如何工作以及您希望如何工作。 – markE