HTML樱花飘落

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樱花效果

FOR YOU GIRL 以梦为马,不负韶华 LOVE YOU FOREVER

实现代码

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />

    <title>落花纷飞</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>
    <canvas id="sakura"></canvas>
    <div class="btnbg"></div>
    <div
      style="
        position: absolute;
        top: 30%;
        left: 18%;
        z-index: 1;
        width: 430px;
        height: 400px;
        font-size: 30px;
        color: #ff826c;
        font-family: 等线;
      "
    >
      <div style="margin-left: 10px; margin-bottom: 20px">FOR YOU:Girl&nbsp;</div>
      <div style="margin-left: 68px; margin-bottom: 20px">
        以梦为马 不负韶华
      </div>
      <div style="margin-left: 180px; font-size: 24px">LOVE YOU FROEVER</div>
    </div>
    <!-- sakura shader -->
    <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;

      varying vec2 texCoord;
      varying vec2 screenCoord;

      void main(void) 
          gl_Position = vec4(aPosition, 0.0, 1.0);
          texCoord = aPosition.xy * 0.5 + vec2(0.5, 0.5);
          screenCoord = aPosition.xy * vec2(uResolution.z, 1.0);
      
    </script>
    <script id="bg_fsh" type="x-shader/x_fragment">
      #ifdef GL_ES
      //precision mediump float;
      precision highp float;
      #endif

      uniform vec2 uTimes;

      varying vec2 texCoord;
      varying vec2 screenCoord;

      void main(void) 
          vec3 col;
          float c;
          vec2 tmpv = texCoord * vec2(0.8, 1.0) - vec2(0.95, 1.0);
          c = exp(-pow(length(tmpv) * 1.8, 2.0));
          col = mix(vec3(0.02, 0.0, 0.03), vec3(0.96, 0.98, 1.0) * 1.5, c);
          gl_FragColor = vec4(col * 0.5, 1.0);
      
    </script>
    <script id="fx_brightbuf_fsh" type="x-shader/x_fragment">
      #ifdef GL_ES
      //precision mediump float;
      precision highp float;
      #endif
      uniform sampler2D uSrc;
      uniform vec2 uDelta;

      varying vec2 texCoord;
      varying vec2 screenCoord;

      void main(void) 
          vec4 col = texture2D(uSrc, texCoord);
          gl_FragColor = vec4(col.rgb * 2.0 - vec3(0.5), 1.0);
      
    </script>
    <script id="fx_dirblur_r4_fsh" type="x-shader/x_fragment">
      #ifdef GL_ES
      //precision mediump float;
      precision highp float;
      #endif
      uniform sampler2D uSrc;
      uniform vec2 uDelta;
      uniform vec4 uBlurDir; //dir(x, y), stride(z, w)

      varying vec2 texCoord;
      varying vec2 screenCoord;

      void main(void) 
          vec4 col = texture2D(uSrc, texCoord);
          col = col + texture2D(uSrc, texCoord + uBlurDir.xy * uDelta);
          col = col + texture2D(uSrc, texCoord - uBlurDir.xy * uDelta);
          col = col + texture2D(uSrc, texCoord + (uBlurDir.xy + uBlurDir.zw) * uDelta);
          col = col + texture2D(uSrc, texCoord - (uBlurDir.xy + uBlurDir.zw) * uDelta);
          gl_FragColor = col / 5.0;
      
    </script>
    <script id="fx_common_fsh" type="x-shader/x_fragment">
      #ifdef GL_ES
      //precision mediump float;
      precision highp float;
      #endif
      uniform sampler2D uSrc;
      uniform vec2 uDelta;

      varying vec2 texCoord;
      varying vec2 screenCoord;

      void main(void) 
          gl_FragColor = texture2D(uSrc, texCoord);
      
    </script>
    <script id="pp_final_vsh" type="x-shader/x_vertex">
      uniform vec3 uResolution;
      attribute vec2 aPosition;
      varying vec2 texCoord;
      varying vec2 screenCoord;
      void main(void) 
          gl_Position = vec4(aPosition, 0.0, 1.0);
          texCoord = aPosition.xy * 0.5 + vec2(0.5, 0.5);
          screenCoord = aPosition.xy * vec2(uResolution.z, 1.0);
      
    </script>
    <script id="pp_final_fsh" type="x-shader/x_fragment">
      #ifdef GL_ES
      //precision mediump float;
      precision highp float;
      #endif
      uniform sampler2D uSrc;
      uniform sampler2D uBloom;
      uniform vec2 uDelta;
      varying vec2 texCoord;
      varying vec2 screenCoord;
      void main(void) 
          vec4 srccol = texture2D(uSrc, texCoord) * 2.0;
          vec4 bloomcol = texture2D(uBloom, texCoord);
          vec4 col;
          col = srccol + bloomcol * (vec4(1.0) + srccol);
          col *= smoothstep(1.0, 0.0, pow(