<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>HTML5 Canvas火球撞击动画特效 - 【更多源码：www.96flw.com】</title>
<style>
canvas{
position: absolute;
height: 100%;
width: 100%;
left: 0;
top: 0;
cursor: crosshair;
}
</style>
</head>
<body>
<canvas></canvas>
<script type="text/javascript">
bgColor = '#111';
gravity = 0.03;
particleColor = '#f73';
canvas = document.querySelector('canvas');
ctx = canvas.getContext('2d');
(onresize = function(){
width = canvas.width = canvas.clientWidth;
height = canvas.height = canvas.clientHeight;
o = {x:Math.floor(width/2),y:Math.floor(height/2)};
edge = {top:-o.y,right:width-o.x,bottom:height-o.y,left:-o.x}
})();
particles = {};
newParticle = (function(){
var nextIndex = 0;
return function(x,y,r,o,c,xv,yv,rv,ov){
particles[++nextIndex] = {
index: nextIndex,
x: x,
y: y,
r: r,
o: o,
c: c,
xv: xv,
yv: yv,
rv: rv,
ov: ov
};
};
})();
fireballs = {};
newFireball = (function(){
var nextIndex = 0;
return function(x,y,xv,yv,life){
fireballs[++nextIndex] = {
index: nextIndex,
x: x,
y: y,
xv: xv,
yv: yv,
life: life
};
};
})();
mouse = {x:0,y:0,d:0};
onmousemove = function(e){
mouse.x = e.clientX-o.x;
mouse.y = e.clientY-o.y;
var dx = mouse.x - pos1.x,
dy = mouse.y - pos1.y;
mouse.d = Math.sqrt(dx*dx+dy*dy);
};
charging = false;
pos1 = {x:0,y:0};
showInstructions = true;
onmousedown = function(e){
pos1.x = mouse.x;
pos1.y = mouse.y;
charging = true;
showInstructions = false;
};
onmouseup = function(){
if(charging){
newFireball(
mouse.x,
mouse.y,
(pos1.x-mouse.x)*0.03,
(pos1.y-mouse.y)*0.03,
600
);
charging = false;
}
};
time = 0;
requestAnimationFrame(loop = function(){
ctx.setTransform(1,0,0,1,0,0);
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 1;
ctx.fillStyle = bgColor;
ctx.fillRect(0,0,width,height);
ctx.translate(o.x,o.y);
if(charging){
var c = Math.floor(30+mouse.d/2);
ctx.strokeStyle = 'rgba('+c+','+c+','+c+',1)';
ctx.lineWidth = 4;
ctx.beginPath();
ctx.moveTo(pos1.x,pos1.y);
ctx.lineTo(mouse.x,mouse.y);
ctx.lineCap = 'round';
ctx.stroke();
}
if(showInstructions){
pos1.x = -70;
pos1.y = -35;
if(time<10){
var x = -70,
y = -35,
r = 30-time*2,
a = time/10;
}else if(time<80){
var x = (time-10)*2-70,
y = (time-10)-35,
r = 10,
a = 1;
}else if(time<90){
var x = 70,
y = 35,
r = 10+(time-80)*2,
a = 1-(time-80)/10;
}else if(time<140){
var x = 70,
y = 35,
r = 30,
a = 0;
}
var dx = pos1.x-x,
dy = pos1.y-y,
d = Math.sqrt(dx*dx+dy*dy);
if(time<80&&time>10){
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = 1;
var c = Math.floor(30+d/2);
ctx.strokeStyle = 'rgba('+c+','+c+','+c+',1)';
ctx.lineWidth = 4;
ctx.beginPath();
ctx.moveTo(pos1.x,pos1.y);
ctx.lineTo(x,y);
ctx.lineCap = 'round';
ctx.stroke();
}
if(time<140){
ctx.globalCompositeOperation = 'source-over';
ctx.globalAlpha = a;
ctx.beginPath();
ctx.arc(x,y,r,0,Math.PI*2);
ctx.lineWidth = 2;
ctx.strokeStyle = '#aaa';
ctx.stroke();
}
if(time==80){
newFireball(
x,
y,
dx*0.03,
dy*0.03,
240
);
}
time = (time+1)%180;
}
ctx.globalCompositeOperation = 'lighter';
for(var i in particles){
var p = particles[i];
ctx.beginPath();
ctx.arc(p.x,p.y,p.r,0,Math.PI*2);
ctx.globalAlpha = p.o;
ctx.fillStyle = p.c;
ctx.fill();
}
for(var i in particles){
var p = particles[i];
p.x += p.xv;
p.y += p.yv;
p.r += p.rv;
p.o += p.ov;
if(p.r<0)delete particles[p.index];
if(p.o<0)delete particles[p.index];
}
for(var i in fireballs){
f = fireballs[i];
var numParticles = Math.sqrt(f.xv*f.xv+f.yv*f.yv)/5;
if(numParticles<1)numParticles=1;
var numParticlesInt = Math.ceil(numParticles),
numParticlesDif = numParticles/numParticlesInt;
for(var j=0;j<numParticlesInt;j++){
newParticle(
f.x-f.xv*j/numParticlesInt,
f.y-f.yv*j/numParticlesInt,
7,
numParticlesDif,
particleColor,
Math.random()*0.6-0.3,
Math.random()*0.6-0.3,
-0.3,
-0.05*numParticlesDif
);
}
f.x += f.xv;
f.y += f.yv;
f.yv += gravity;
var boundary;
if(f.y<(boundary = edge.top+7)){
f.y = boundary;
f.yv *= -1;
}else if(f.y>(boundary = edge.bottom-7)){
f.y = boundary;
f.yv *= -1;
}
if(f.x>(boundary = edge.right-7)){
f.x = boundary;
f.xv *= -1;
}else if(f.x<(boundary = edge.left+7)){
f.x = boundary;
f.xv *= -1;
}
if(--f.life<0)delete fireballs[f.index];
}
requestAnimationFrame(loop);
});
</script>
</body>
</html>
