CSS樱花

运行
1 2	`npm install http-server -g http-server`
效果图:
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</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>

  <!-- 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>
  <!-- effects -->
  <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>
  <!-- effect fragment shader template -->
  <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>
  <!-- post processing -->
  <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(length((texCoord - vec2(0.5)) * 2.0), 1.2) * 0.5);
    col = pow(col, vec4(0.45454545454545)); //(1.0 / 2.2)

    gl_FragColor = vec4(col.rgb, 1.0);
    gl_FragColor.a = 1.0;
}
</script>

  <script>
    // Utilities
    var Vector3 = {};
    var Matrix44 = {};
    Vector3.create = function (x, y, z) {
      return { 'x': x, 'y': y, 'z': z };
    };
    Vector3.dot = function (v0, v1) {
      return v0.x * v1.x + v0.y * v1.y + v0.z * v1.z;
    };
    Vector3.cross = function (v, v0, v1) {
      v.x = v0.y * v1.z - v0.z * v1.y;
      v.y = v0.z * v1.x - v0.x * v1.z;
      v.z = v0.x * v1.y - v0.y * v1.x;
    };
    Vector3.normalize = function (v) {
      var l = v.x * v.x + v.y * v.y + v.z * v.z;
      if (l > 0.00001) {
        l = 1.0 / Math.sqrt(l);
        v.x *= l;
        v.y *= l;
        v.z *= l;
      }
    };
    Vector3.arrayForm = function (v) {
      if (v.array) {
        v.array[0] = v.x;
        v.array[1] = v.y;
        v.array[2] = v.z;
      }
      else {
        v.array = new Float32Array([v.x, v.y, v.z]);
      }
      return v.array;
    };
    Matrix44.createIdentity = function () {
      return new Float32Array([1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0]);
    };
    Matrix44.loadProjection = function (m, aspect, vdeg, near, far) {
      var h = near * Math.tan(vdeg * Math.PI / 180.0 * 0.5) * 2.0;
      var w = h * aspect;

      m[0] = 2.0 * near / w;
      m[1] = 0.0;
      m[2] = 0.0;
      m[3] = 0.0;

      m[4] = 0.0;
      m[5] = 2.0 * near / h;
      m[6] = 0.0;
      m[7] = 0.0;

      m[8] = 0.0;
      m[9] = 0.0;
      m[10] = -(far + near) / (far - near);
      m[11] = -1.0;

      m[12] = 0.0;
      m[13] = 0.0;
      m[14] = -2.0 * far * near / (far - near);
      m[15] = 0.0;
    };
    Matrix44.loadLookAt = function (m, vpos, vlook, vup) {
      var frontv = Vector3.create(vpos.x - vlook.x, vpos.y - vlook.y, vpos.z - vlook.z);
      Vector3.normalize(frontv);
      var sidev = Vector3.create(1.0, 0.0, 0.0);
      Vector3.cross(sidev, vup, frontv);
      Vector3.normalize(sidev);
      var topv = Vector3.create(1.0, 0.0, 0.0);
      Vector3.cross(topv, frontv, sidev);
      Vector3.normalize(topv);

      m[0] = sidev.x;
      m[1] = topv.x;
      m[2] = frontv.x;
      m[3] = 0.0;

      m[4] = sidev.y;
      m[5] = topv.y;
      m[6] = frontv.y;
      m[7] = 0.0;

      m[8] = sidev.z;
      m[9] = topv.z;
      m[10] = frontv.z;
      m[11] = 0.0;

      m[12] = -(vpos.x * m[0] + vpos.y * m[4] + vpos.z * m[8]);
      m[13] = -(vpos.x * m[1] + vpos.y * m[5] + vpos.z * m[9]);
      m[14] = -(vpos.x * m[2] + vpos.y * m[6] + vpos.z * m[10]);
      m[15] = 1.0;
    };

    //
    var timeInfo = {
      'start': 0, 'prev': 0, // Date
      'delta': 0, 'elapsed': 0 // Number(sec)
    };

    //
    var gl;
    var renderSpec = {
      'width': 0,
      'height': 0,
      'aspect': 1,
      'array': new Float32Array(3),
      'halfWidth': 0,
      'halfHeight': 0,
      'halfArray': new Float32Array(3)
      // and some render targets. see setViewport()
    };
    renderSpec.setSize = function (w, h) {
      renderSpec.width = w;
      renderSpec.height = h;
      renderSpec.aspect = renderSpec.width / renderSpec.height;
      renderSpec.array[0] = renderSpec.width;
      renderSpec.array[1] = renderSpec.height;
      renderSpec.array[2] = renderSpec.aspect;

      renderSpec.halfWidth = Math.floor(w / 2);
      renderSpec.halfHeight = Math.floor(h / 2);
      renderSpec.halfArray[0] = renderSpec.halfWidth;
      renderSpec.halfArray[1] = renderSpec.halfHeight;
      renderSpec.halfArray[2] = renderSpec.halfWidth / renderSpec.halfHeight;
    };

    function deleteRenderTarget(rt) {
      gl.deleteFramebuffer(rt.frameBuffer);
      gl.deleteRenderbuffer(rt.renderBuffer);
      gl.deleteTexture(rt.texture);
    }

    function createRenderTarget(w, h) {
      var ret = {
        'width': w,
        'height': h,
        'sizeArray': new Float32Array([w, h, w / h]),
        'dtxArray': new Float32Array([1.0 / w, 1.0 / h])
      };
      ret.frameBuffer = gl.createFramebuffer();
      ret.renderBuffer = gl.createRenderbuffer();
      ret.texture = gl.createTexture();

      gl.bindTexture(gl.TEXTURE_2D, ret.texture);
      gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, w, h, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
      gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

      gl.bindFramebuffer(gl.FRAMEBUFFER, ret.frameBuffer);
      gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, ret.texture, 0);

      gl.bindRenderbuffer(gl.RENDERBUFFER, ret.renderBuffer);
      gl.renderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, w, h);
      gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, ret.renderBuffer);

      gl.bindTexture(gl.TEXTURE_2D, null);
      gl.bindRenderbuffer(gl.RENDERBUFFER, null);
      gl.bindFramebuffer(gl.FRAMEBUFFER, null);

      return ret;
    }

    function compileShader(shtype, shsrc) {
      var retsh = gl.createShader(shtype);

      gl.shaderSource(retsh, shsrc);
      gl.compileShader(retsh);

      if (!gl.getShaderParameter(retsh, gl.COMPILE_STATUS)) {
        var errlog = gl.getShaderInfoLog(retsh);
        gl.deleteShader(retsh);
        console.error(errlog);
        return null;
      }
      return retsh;
    }

    function createShader(vtxsrc, frgsrc, uniformlist, attrlist) {
      var vsh = compileShader(gl.VERTEX_SHADER, vtxsrc);
      var fsh = compileShader(gl.FRAGMENT_SHADER, frgsrc);

      if (vsh == null || fsh == null) {
        return null;
      }

      var prog = gl.createProgram();
      gl.attachShader(prog, vsh);
      gl.attachShader(prog, fsh);

      gl.deleteShader(vsh);
      gl.deleteShader(fsh);

      gl.linkProgram(prog);
      if (!gl.getProgramParameter(prog, gl.LINK_STATUS)) {
        var errlog = gl.getProgramInfoLog(prog);
        console.error(errlog);
        return null;
      }

      if (uniformlist) {
        prog.uniforms = {};
        for (var i = 0; i < uniformlist.length; i++) {
          prog.uniforms[uniformlist[i]] = gl.getUniformLocation(prog, uniformlist[i]);
        }
      }

      if (attrlist) {
        prog.attributes = {};
        for (var i = 0; i < attrlist.length; i++) {
          var attr = attrlist[i];
          prog.attributes[attr] = gl.getAttribLocation(prog, attr);
        }
      }

      return prog;
    }

    function useShader(prog) {
      gl.useProgram(prog);
      for (var attr in prog.attributes) {
        gl.enableVertexAttribArray(prog.attributes[attr]);;
      }
    }

    function unuseShader(prog) {
      for (var attr in prog.attributes) {
        gl.disableVertexAttribArray(prog.attributes[attr]);;
      }
      gl.useProgram(null);
    }

    var projection = {
      'angle': 60,
      'nearfar': new Float32Array([0.1, 100.0]),
      'matrix': Matrix44.createIdentity()
    };
    var camera = {
      'position': Vector3.create(0, 0, 100),
      'lookat': Vector3.create(0, 0, 0),
      'up': Vector3.create(0, 1, 0),
      'dof': Vector3.create(10.0, 4.0, 8.0),
      'matrix': Matrix44.createIdentity()
    };

    var pointFlower = {};
    var meshFlower = {};
    var sceneStandBy = false;

    var BlossomParticle = function () {
      this.velocity = new Array(3);
      this.rotation = new Array(3);
      this.position = new Array(3);
      this.euler = new Array(3);
      this.size = 1.0;
      this.alpha = 1.0;
      this.zkey = 0.0;
    };

    BlossomParticle.prototype.setVelocity = function (vx, vy, vz) {
      this.velocity[0] = vx;
      this.velocity[1] = vy;
      this.velocity[2] = vz;
    };

    BlossomParticle.prototype.setRotation = function (rx, ry, rz) {
      this.rotation[0] = rx;
      this.rotation[1] = ry;
      this.rotation[2] = rz;
    };

    BlossomParticle.prototype.setPosition = function (nx, ny, nz) {
      this.position[0] = nx;
      this.position[1] = ny;
      this.position[2] = nz;
    };

    BlossomParticle.prototype.setEulerAngles = function (rx, ry, rz) {
      this.euler[0] = rx;
      this.euler[1] = ry;
      this.euler[2] = rz;
    };

    BlossomParticle.prototype.setSize = function (s) {
      this.size = s;
    };

    BlossomParticle.prototype.update = function (dt, et) {
      this.position[0] += this.velocity[0] * dt;
      this.position[1] += this.velocity[1] * dt;
      this.position[2] += this.velocity[2] * dt;

      this.euler[0] += this.rotation[0] * dt;
      this.euler[1] += this.rotation[1] * dt;
      this.euler[2] += this.rotation[2] * dt;
    };

    function createPointFlowers() {
      // get point sizes
      var prm = gl.getParameter(gl.ALIASED_POINT_SIZE_RANGE);
      renderSpec.pointSize = { 'min': prm[0], 'max': prm[1] };

      var vtxsrc = document.getElementById("sakura_point_vsh").textContent;
      var frgsrc = document.getElementById("sakura_point_fsh").textContent;

      pointFlower.program = createShader(
        vtxsrc, frgsrc,
        ['uProjection', 'uModelview', 'uResolution', 'uOffset', 'uDOF', 'uFade'],
        ['aPosition', 'aEuler', 'aMisc']
      );

      useShader(pointFlower.program);
      pointFlower.offset = new Float32Array([0.0, 0.0, 0.0]);
      pointFlower.fader = Vector3.create(0.0, 10.0, 0.0);

      // paramerters: velocity[3], rotate[3]
      pointFlower.numFlowers = 1600;
      pointFlower.particles = new Array(pointFlower.numFlowers);
      // vertex attributes {position[3], euler_xyz[3], size[1]}
      pointFlower.dataArray = new Float32Array(pointFlower.numFlowers * (3 + 3 + 2));
      pointFlower.positionArrayOffset = 0;
      pointFlower.eulerArrayOffset = pointFlower.numFlowers * 3;
      pointFlower.miscArrayOffset = pointFlower.numFlowers * 6;

      pointFlower.buffer = gl.createBuffer();
      gl.bindBuffer(gl.ARRAY_BUFFER, pointFlower.buffer);
      gl.bufferData(gl.ARRAY_BUFFER, pointFlower.dataArray, gl.DYNAMIC_DRAW);
      gl.bindBuffer(gl.ARRAY_BUFFER, null);

      unuseShader(pointFlower.program);

      for (var i = 0; i < pointFlower.numFlowers; i++) {
        pointFlower.particles[i] = new BlossomParticle();
      }
    }

    function initPointFlowers() {
      //area
      pointFlower.area = Vector3.create(20.0, 20.0, 20.0);
      pointFlower.area.x = pointFlower.area.y * renderSpec.aspect;

      pointFlower.fader.x = 10.0; //env fade start
      pointFlower.fader.y = pointFlower.area.z; //env fade half
      pointFlower.fader.z = 0.1;  //near fade start

      //particles
      var PI2 = Math.PI * 2.0;
      var tmpv3 = Vector3.create(0, 0, 0);
      var tmpv = 0;
      var symmetryrand = function () { return (Math.random() * 2.0 - 1.0); };
      for (var i = 0; i < pointFlower.numFlowers; i++) {
        var tmpprtcl = pointFlower.particles[i];

        //velocity
        tmpv3.x = symmetryrand() * 0.3 + 0.8;
        tmpv3.y = symmetryrand() * 0.2 - 1.0;
        tmpv3.z = symmetryrand() * 0.3 + 0.5;
        Vector3.normalize(tmpv3);
        tmpv = 2.0 + Math.random() * 1.0;
        tmpprtcl.setVelocity(tmpv3.x * tmpv, tmpv3.y * tmpv, tmpv3.z * tmpv);

        //rotation
        tmpprtcl.setRotation(
          symmetryrand() * PI2 * 0.5,
          symmetryrand() * PI2 * 0.5,
          symmetryrand() * PI2 * 0.5
        );

        //position
        tmpprtcl.setPosition(
          symmetryrand() * pointFlower.area.x,
          symmetryrand() * pointFlower.area.y,
          symmetryrand() * pointFlower.area.z
        );

        //euler
        tmpprtcl.setEulerAngles(
          Math.random() * Math.PI * 2.0,
          Math.random() * Math.PI * 2.0,
          Math.random() * Math.PI * 2.0
        );

        //size
        tmpprtcl.setSize(0.9 + Math.random() * 0.1);
      }
    }

    function renderPointFlowers() {
      //update
      var PI2 = Math.PI * 2.0;
      var limit = [pointFlower.area.x, pointFlower.area.y, pointFlower.area.z];
      var repeatPos = function (prt, cmp, limit) {
        if (Math.abs(prt.position[cmp]) - prt.size * 0.5 > limit) {
          //out of area
          if (prt.position[cmp] > 0) {
            prt.position[cmp] -= limit * 2.0;
          }
          else {
            prt.position[cmp] += limit * 2.0;
          }
        }
      };
      var repeatEuler = function (prt, cmp) {
        prt.euler[cmp] = prt.euler[cmp] % PI2;
        if (prt.euler[cmp] < 0.0) {
          prt.euler[cmp] += PI2;
        }
      };

      for (var i = 0; i < pointFlower.numFlowers; i++) {
        var prtcl = pointFlower.particles[i];
        prtcl.update(timeInfo.delta, timeInfo.elapsed);
        repeatPos(prtcl, 0, pointFlower.area.x);
        repeatPos(prtcl, 1, pointFlower.area.y);
        repeatPos(prtcl, 2, pointFlower.area.z);
        repeatEuler(prtcl, 0);
        repeatEuler(prtcl, 1);
        repeatEuler(prtcl, 2);

        prtcl.alpha = 1.0;//(pointFlower.area.z - prtcl.position[2]) * 0.5;

        prtcl.zkey = (camera.matrix[2] * prtcl.position[0]
          + camera.matrix[6] * prtcl.position[1]
          + camera.matrix[10] * prtcl.position[2]
          + camera.matrix[14]);
      }

      // sort
      pointFlower.particles.sort(function (p0, p1) { return p0.zkey - p1.zkey; });

      // update data
      var ipos = pointFlower.positionArrayOffset;
      var ieuler = pointFlower.eulerArrayOffset;
      var imisc = pointFlower.miscArrayOffset;
      for (var i = 0; i < pointFlower.numFlowers; i++) {
        var prtcl = pointFlower.particles[i];
        pointFlower.dataArray[ipos] = prtcl.position[0];
        pointFlower.dataArray[ipos + 1] = prtcl.position[1];
        pointFlower.dataArray[ipos + 2] = prtcl.position[2];
        ipos += 3;
        pointFlower.dataArray[ieuler] = prtcl.euler[0];
        pointFlower.dataArray[ieuler + 1] = prtcl.euler[1];
        pointFlower.dataArray[ieuler + 2] = prtcl.euler[2];
        ieuler += 3;
        pointFlower.dataArray[imisc] = prtcl.size;
        pointFlower.dataArray[imisc + 1] = prtcl.alpha;
        imisc += 2;
      }

      //draw
      gl.enable(gl.BLEND);
      //gl.disable(gl.DEPTH_TEST);
      gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);

      var prog = pointFlower.program;
      useShader(prog);

      gl.uniformMatrix4fv(prog.uniforms.uProjection, false, projection.matrix);
      gl.uniformMatrix4fv(prog.uniforms.uModelview, false, camera.matrix);
      gl.uniform3fv(prog.uniforms.uResolution, renderSpec.array);
      gl.uniform3fv(prog.uniforms.uDOF, Vector3.arrayForm(camera.dof));
      gl.uniform3fv(prog.uniforms.uFade, Vector3.arrayForm(pointFlower.fader));

      gl.bindBuffer(gl.ARRAY_BUFFER, pointFlower.buffer);
      gl.bufferData(gl.ARRAY_BUFFER, pointFlower.dataArray, gl.DYNAMIC_DRAW);

      gl.vertexAttribPointer(prog.attributes.aPosition, 3, gl.FLOAT, false, 0, pointFlower.positionArrayOffset * Float32Array.BYTES_PER_ELEMENT);
      gl.vertexAttribPointer(prog.attributes.aEuler, 3, gl.FLOAT, false, 0, pointFlower.eulerArrayOffset * Float32Array.BYTES_PER_ELEMENT);
      gl.vertexAttribPointer(prog.attributes.aMisc, 2, gl.FLOAT, false, 0, pointFlower.miscArrayOffset * Float32Array.BYTES_PER_ELEMENT);

      // doubler
      for (var i = 1; i < 2; i++) {
        var zpos = i * -2.0;
        pointFlower.offset[0] = pointFlower.area.x * -1.0;
        pointFlower.offset[1] = pointFlower.area.y * -1.0;
        pointFlower.offset[2] = pointFlower.area.z * zpos;
        gl.uniform3fv(prog.uniforms.uOffset, pointFlower.offset);
        gl.drawArrays(gl.POINT, 0, pointFlower.numFlowers);

        pointFlower.offset[0] = pointFlower.area.x * -1.0;
        pointFlower.offset[1] = pointFlower.area.y * 1.0;
        pointFlower.offset[2] = pointFlower.area.z * zpos;
        gl.uniform3fv(prog.uniforms.uOffset, pointFlower.offset);
        gl.drawArrays(gl.POINT, 0, pointFlower.numFlowers);

        pointFlower.offset[0] = pointFlower.area.x * 1.0;
        pointFlower.offset[1] = pointFlower.area.y * -1.0;
        pointFlower.offset[2] = pointFlower.area.z * zpos;
        gl.uniform3fv(prog.uniforms.uOffset, pointFlower.offset);
        gl.drawArrays(gl.POINT, 0, pointFlower.numFlowers);

        pointFlower.offset[0] = pointFlower.area.x * 1.0;
        pointFlower.offset[1] = pointFlower.area.y * 1.0;
        pointFlower.offset[2] = pointFlower.area.z * zpos;
        gl.uniform3fv(prog.uniforms.uOffset, pointFlower.offset);
        gl.drawArrays(gl.POINT, 0, pointFlower.numFlowers);
      }

      //main
      pointFlower.offset[0] = 0.0;
      pointFlower.offset[1] = 0.0;
      pointFlower.offset[2] = 0.0;
      gl.uniform3fv(prog.uniforms.uOffset, pointFlower.offset);
      gl.drawArrays(gl.POINT, 0, pointFlower.numFlowers);

      gl.bindBuffer(gl.ARRAY_BUFFER, null);
      unuseShader(prog);

      gl.enable(gl.DEPTH_TEST);
      gl.disable(gl.BLEND);
    }

    // effects
    //common util
    function createEffectProgram(vtxsrc, frgsrc, exunifs, exattrs) {
      var ret = {};
      var unifs = ['uResolution', 'uSrc', 'uDelta'];
      if (exunifs) {
        unifs = unifs.concat(exunifs);
      }
      var attrs = ['aPosition'];
      if (exattrs) {
        attrs = attrs.concat(exattrs);
      }

      ret.program = createShader(vtxsrc, frgsrc, unifs, attrs);
      useShader(ret.program);

      ret.dataArray = new Float32Array([
        -1.0, -1.0,
        1.0, -1.0,
        -1.0, 1.0,
        1.0, 1.0
      ]);
      ret.buffer = gl.createBuffer();
      gl.bindBuffer(gl.ARRAY_BUFFER, ret.buffer);
      gl.bufferData(gl.ARRAY_BUFFER, ret.dataArray, gl.STATIC_DRAW);

      gl.bindBuffer(gl.ARRAY_BUFFER, null);
      unuseShader(ret.program);

      return ret;
    }

    function useEffect(fxobj, srctex) {
      var prog = fxobj.program;
      useShader(prog);
      gl.uniform3fv(prog.uniforms.uResolution, renderSpec.array);

      if (srctex != null) {
        gl.uniform2fv(prog.uniforms.uDelta, srctex.dtxArray);
        gl.uniform1i(prog.uniforms.uSrc, 0);

        gl.activeTexture(gl.TEXTURE0);
        gl.bindTexture(gl.TEXTURE_2D, srctex.texture);
      }
    }
    function drawEffect(fxobj) {
      gl.bindBuffer(gl.ARRAY_BUFFER, fxobj.buffer);
      gl.vertexAttribPointer(fxobj.program.attributes.aPosition, 2, gl.FLOAT, false, 0, 0);
      gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
    }
    function unuseEffect(fxobj) {
      unuseShader(fxobj.program);
    }

    var effectLib = {};
    function createEffectLib() {

      var vtxsrc, frgsrc;
      //common
      var cmnvtxsrc = document.getElementById("fx_common_vsh").textContent;

      //background
      frgsrc = document.getElementById("bg_fsh").textContent;
      effectLib.sceneBg = createEffectProgram(cmnvtxsrc, frgsrc, ['uTimes'], null);

      // make brightpixels buffer
      frgsrc = document.getElementById("fx_brightbuf_fsh").textContent;
      effectLib.mkBrightBuf = createEffectProgram(cmnvtxsrc, frgsrc, null, null);

      // direction blur
      frgsrc = document.getElementById("fx_dirblur_r4_fsh").textContent;
      effectLib.dirBlur = createEffectProgram(cmnvtxsrc, frgsrc, ['uBlurDir'], null);

      //final composite
      vtxsrc = document.getElementById("pp_final_vsh").textContent;
      frgsrc = document.getElementById("pp_final_fsh").textContent;
      effectLib.finalComp = createEffectProgram(vtxsrc, frgsrc, ['uBloom'], null);
    }

    // background
    function createBackground() {
      //console.log("create background");
    }
    function initBackground() {
      //console.log("init background");
    }
    function renderBackground() {
      gl.disable(gl.DEPTH_TEST);

      useEffect(effectLib.sceneBg, null);
      gl.uniform2f(effectLib.sceneBg.program.uniforms.uTimes, timeInfo.elapsed, timeInfo.delta);
      drawEffect(effectLib.sceneBg);
      unuseEffect(effectLib.sceneBg);

      gl.enable(gl.DEPTH_TEST);
    }

    // post process
    var postProcess = {};
    function createPostProcess() {
      //console.log("create post process");
    }
    function initPostProcess() {
      //console.log("init post process");
    }

    function renderPostProcess() {
      gl.enable(gl.TEXTURE_2D);
      gl.disable(gl.DEPTH_TEST);
      var bindRT = function (rt, isclear) {
        gl.bindFramebuffer(gl.FRAMEBUFFER, rt.frameBuffer);
        gl.viewport(0, 0, rt.width, rt.height);
        if (isclear) {
          gl.clearColor(0, 0, 0, 0);
          gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
        }
      };

      //make bright buff
      bindRT(renderSpec.wHalfRT0, true);
      useEffect(effectLib.mkBrightBuf, renderSpec.mainRT);
      drawEffect(effectLib.mkBrightBuf);
      unuseEffect(effectLib.mkBrightBuf);

      // make bloom
      for (var i = 0; i < 2; i++) {
        var p = 1.5 + 1 * i;
        var s = 2.0 + 1 * i;
        bindRT(renderSpec.wHalfRT1, true);
        useEffect(effectLib.dirBlur, renderSpec.wHalfRT0);
        gl.uniform4f(effectLib.dirBlur.program.uniforms.uBlurDir, p, 0.0, s, 0.0);
        drawEffect(effectLib.dirBlur);
        unuseEffect(effectLib.dirBlur);

        bindRT(renderSpec.wHalfRT0, true);
        useEffect(effectLib.dirBlur, renderSpec.wHalfRT1);
        gl.uniform4f(effectLib.dirBlur.program.uniforms.uBlurDir, 0.0, p, 0.0, s);
        drawEffect(effectLib.dirBlur);
        unuseEffect(effectLib.dirBlur);
      }

      //display
      gl.bindFramebuffer(gl.FRAMEBUFFER, null);
      gl.viewport(0, 0, renderSpec.width, renderSpec.height);
      gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

      useEffect(effectLib.finalComp, renderSpec.mainRT);
      gl.uniform1i(effectLib.finalComp.program.uniforms.uBloom, 1);
      gl.activeTexture(gl.TEXTURE1);
      gl.bindTexture(gl.TEXTURE_2D, renderSpec.wHalfRT0.texture);
      drawEffect(effectLib.finalComp);
      unuseEffect(effectLib.finalComp);

      gl.enable(gl.DEPTH_TEST);
    }


    var SceneEnv = {};
    function createScene() {
      createEffectLib();
      createBackground();
      createPointFlowers();
      createPostProcess();
      sceneStandBy = true;
    }

    function initScene() {
      initBackground();
      initPointFlowers();
      initPostProcess();

      //camera.position.z = 17.320508;
      camera.position.z = pointFlower.area.z + projection.nearfar[0];
      projection.angle = Math.atan2(pointFlower.area.y, camera.position.z + pointFlower.area.z) * 180.0 / Math.PI * 2.0;
      Matrix44.loadProjection(projection.matrix, renderSpec.aspect, projection.angle, projection.nearfar[0], projection.nearfar[1]);
    }

    function renderScene() {
      //draw
      Matrix44.loadLookAt(camera.matrix, camera.position, camera.lookat, camera.up);

      gl.enable(gl.DEPTH_TEST);

      //gl.bindFramebuffer(gl.FRAMEBUFFER, null);
      gl.bindFramebuffer(gl.FRAMEBUFFER, renderSpec.mainRT.frameBuffer);
      gl.viewport(0, 0, renderSpec.mainRT.width, renderSpec.mainRT.height);
      gl.clearColor(0.005, 0, 0.05, 0);
      gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

      renderBackground();
      renderPointFlowers();
      renderPostProcess();
    }


    function onResize(e) {
      makeCanvasFullScreen(document.getElementById("sakura"));
      setViewports();
      if (sceneStandBy) {
        initScene();
      }
    }

    function setViewports() {
      renderSpec.setSize(gl.canvas.width, gl.canvas.height);

      gl.clearColor(0.2, 0.2, 0.5, 1.0);
      gl.viewport(0, 0, renderSpec.width, renderSpec.height);

      var rtfunc = function (rtname, rtw, rth) {
        var rt = renderSpec[rtname];
        if (rt) deleteRenderTarget(rt);
        renderSpec[rtname] = createRenderTarget(rtw, rth);
      };
      rtfunc('mainRT', renderSpec.width, renderSpec.height);
      rtfunc('wFullRT0', renderSpec.width, renderSpec.height);
      rtfunc('wFullRT1', renderSpec.width, renderSpec.height);
      rtfunc('wHalfRT0', renderSpec.halfWidth, renderSpec.halfHeight);
      rtfunc('wHalfRT1', renderSpec.halfWidth, renderSpec.halfHeight);
    }

    function render() {
      renderScene();
    }

    var animating = true;
    function toggleAnimation(elm) {
      animating ^= true;
      if (animating) animate();
      if (elm) {
        elm.innerHTML = animating ? "Stop" : "Start";
      }
    }

    function stepAnimation() {
      if (!animating) animate();
    }

    function animate() {
      var curdate = new Date();
      timeInfo.elapsed = (curdate - timeInfo.start) / 1000.0;
      timeInfo.delta = (curdate - timeInfo.prev) / 1000.0;
      timeInfo.prev = curdate;

      if (animating) requestAnimationFrame(animate);
      render();
    }

    function makeCanvasFullScreen(canvas) {
      var b = document.body;
      var d = document.documentElement;
      fullw = Math.max(b.clientWidth, b.scrollWidth, d.scrollWidth, d.clientWidth);
      fullh = Math.max(b.clientHeight, b.scrollHeight, d.scrollHeight, d.clientHeight);
      canvas.width = fullw;
      canvas.height = fullh;
    }

    window.addEventListener('load', function (e) {
      var canvas = document.getElementById("sakura");
      try {
        makeCanvasFullScreen(canvas);
        gl = canvas.getContext('experimental-webgl');
      } catch (e) {
        alert("WebGL not supported." + e);
        console.error(e);
        return;
      }

      window.addEventListener('resize', onResize);

      setViewports();
      createScene();
      initScene();

      timeInfo.start = new Date();
      timeInfo.prev = timeInfo.start;
      animate();
    });

    //set window.requestAnimationFrame
    (function (w, r) {
      w['r' + r] = w['r' + r] || w['webkitR' + r] || w['mozR' + r] || w['msR' + r] || w['oR' + r] || function (c) { w.setTimeout(c, 1000 / 60); };
    })(window, 'equestAnimationFrame');
  </script>

</body>

</html>
CSS
#樱花 #CSS
CSS樱花
https://xiamu.icu/CSS/CSS樱花/
作者
肉豆蔻吖
发布于
2023年3月30日
许可协议
这么可爱真是抱歉上一篇
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