前端特效CSS样式樱花

下面直接上代码:

<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>cloth</title>
<style>
body {
padding:0;
margin:0;
overflow:hidden;
height: 600px;
}
canvas {
padding:0;
margin:0;
}
div.btnbg {
position:fixed;
left:0;
top:0;
}
</style>
</head>
<body>

<script id="sakura_point_vsh" type="x-shader/x_vertex">
uniform mat4 uProjection;
uniform mat4 uModelview;
uniform vec3 uResolution;
uniform vec3 uOffset;
uniform vec3 uDOF; //x:focus distance, y:focus radius, z:max radius
uniform vec3 uFade; //x:start distance, y:half distance, z:near fade start

attribute vec3 aPosition;
attribute vec3 aEuler;
attribute vec2 aMisc; //x:size, y:fade

varying vec3 pposition;
varying float psize;
varying float palpha;
varying float pdist;

//varying mat3 rotMat;
varying vec3 normX;
varying vec3 normY;
varying vec3 normZ;
varying vec3 normal;

varying float diffuse;
varying float specular;
varying float rstop;
varying float distancefade;

void main(void) {
// Projection is based on vertical angle
vec4 pos = uModelview * vec4(aPosition + uOffset, 1.0);
gl_Position = uProjection * pos;
gl_PointSize = aMisc.x * uProjection[1][1] / -pos.z * uResolution.y * 0.5;

pposition = pos.xyz;
psize = aMisc.x;
pdist = length(pos.xyz);
palpha = smoothstep(0.0, 1.0, (pdist - 0.1) / uFade.z);

vec3 elrsn = sin(aEuler);
vec3 elrcs = cos(aEuler);
mat3 rotx = mat3(
1.0, 0.0, 0.0,
0.0, elrcs.x, elrsn.x,
0.0, -elrsn.x, elrcs.x
);
mat3 roty = mat3(
elrcs.y, 0.0, -elrsn.y,
0.0, 1.0, 0.0,
elrsn.y, 0.0, elrcs.y
);
mat3 rotz = mat3(
elrcs.z, elrsn.z, 0.0,
-elrsn.z, elrcs.z, 0.0,
0.0, 0.0, 1.0
);
mat3 rotmat = rotx * roty * rotz;
normal = rotmat[2];

mat3 trrotm = mat3(
rotmat[0][0], rotmat[1][0], rotmat[2][0],
rotmat[0][1], rotmat[1][1], rotmat[2][1],
rotmat[0][2], rotmat[1][2], rotmat[2][2]
);
normX = trrotm[0];
normY = trrotm[1];
normZ = trrotm[2];

const vec3 lit = vec3(0.6917144638660746, 0.6917144638660746, -0.20751433915982237);

float tmpdfs = dot(lit, normal);
if(tmpdfs < 0.0) {
normal = -normal;
tmpdfs = dot(lit, normal);
}
diffuse = 0.4 + tmpdfs;

vec3 eyev = normalize(-pos.xyz);
if(dot(eyev, normal) > 0.0) {
vec3 hv = normalize(eyev + lit);
specular = pow(max(dot(hv, normal), 0.0), 20.0);
}
else {
specular = 0.0;
}

rstop = clamp((abs(pdist - uDOF.x) - uDOF.y) / uDOF.z, 0.0, 1.0);
rstop = pow(rstop, 0.5);
//-0.69315 = ln(0.5)
distancefade = min(1.0, exp((uFade.x - pdist) * 0.69315 / uFade.y));
}
</script>
<script id="sakura_point_fsh" type="x-shader/x_fragment">
#ifdef GL_ES
//precision mediump float;
precision highp float;
#endif

uniform vec3 uDOF; //x:focus distance, y:focus radius, z:max radius
uniform vec3 uFade; //x:start distance, y:half distance, z:near fade start

const vec3 fadeCol = vec3(0.08, 0.03, 0.06);

varying vec3 pposition;
varying float psize;
varying float palpha;
varying float pdist;

//varying mat3 rotMat;
varying vec3 normX;
varying vec3 normY;
varying vec3 normZ;
varying vec3 normal;

varying float diffuse;
varying float specular;
varying float rstop;
varying float distancefade;

float ellipse(vec2 p, vec2 o, vec2 r) {
vec2 lp = (p - o) / r;
return length(lp) - 1.0;
}

void main(void) {
vec3 p = vec3(gl_PointCoord - vec2(0.5, 0.5), 0.0) * 2.0;
vec3 d = vec3(0.0, 0.0, -1.0);
float nd = normZ.z; //dot(-normZ, d);
if(abs(nd) < 0.0001) discard;

float np = dot(normZ, p);
vec3 tp = p + d * np / nd;
vec2 coord = vec2(dot(normX, tp), dot(normY, tp));

//angle = 15 degree
const float flwrsn = 0.258819045102521;
const float flwrcs = 0.965925826289068;
mat2 flwrm = mat2(flwrcs, -flwrsn, flwrsn, flwrcs);
vec2 flwrp = vec2(abs(coord.x), coord.y) * flwrm;

float r;
if(flwrp.x < 0.0) {
r = ellipse(flwrp, vec2(0.065, 0.024) * 0.5, vec2(0.36, 0.96) * 0.5);
}
else {
r = ellipse(flwrp, vec2(0.065, 0.024) * 0.5, vec2(0.58, 0.96) * 0.5);
}

if(r > rstop) discard;

vec3 col = mix(vec3(1.0, 0.8, 0.75), vec3(1.0, 0.9, 0.87), r);
float grady = mix(0.0, 1.0, pow(coord.y * 0.5 + 0.5, 0.35));
col *= vec3(1.0, grady, grady);
col *= mix(0.8, 1.0, pow(abs(coord.x), 0.3));
col = col * diffuse + specular;

col = mix(fadeCol, col, distancefade);

float alpha = (rstop > 0.001)? (0.5 - r / (rstop * 2.0)) : 1.0;
alpha = smoothstep(0.0, 1.0, alpha) * palpha;

gl_FragColor = vec4(col * 0.5, alpha);
}
</script>

<script id="fx_common_vsh" type="x-shader/x_vertex">
uniform vec3 uResolution;
attribute vec2 aPosition;