Question

有没有人有一个样本用于在javascript中绘制细分的二十面体，他们能够分享？

Answer 1

我有一个使用二十面体的球体曲面细分算法。网上有很多地方可以找到它们，但可以随意使用和修改我的实现。虽然我必须说，我的实现并不是最好的，当它来到内存时，一些顶点是重复的。

    function initSphere(subs){
    if(typeof(subs) == 'undefined'){
        subs = 1;
    }
    var t = (1+Math.sqrt(5))/2;
    var tau = t/Math.sqrt(1+t*t);
    var one = 1/Math.sqrt(1+t*t);
    var pos = [tau, one, 0.0,
              -tau, one, 0.0,
              -tau, -one, 0.0,
              tau, -one, 0.0,
              one, 0.0 ,  tau,
              one, 0.0 , -tau,
              -one, 0.0 , -tau,
              -one, 0.0 , tau,
              0.0 , tau, one,
              0.0 , -tau, one,
              0.0 , -tau, -one,
              0.0 , tau, -one];
    var _indices =  [4, 8, 7,
                    4, 7, 9,
                    5, 6, 11,
                    5, 10, 6,
                    0, 4, 3,
                    0, 3, 5,
                    2, 7, 1,
                    2, 1, 6,
                    8, 0, 11,
                    8, 11, 1,
                    9, 10, 3,
                    9, 2, 10,
                    8, 4, 0,
                    11, 0, 5,
                    4, 9, 3,
                    5, 3, 10,
                    7, 8, 1,
                    6, 1, 11,
                    7, 2, 9,
                    6, 10, 2];

    for(var i = 0;i<subs;i++){
        var newIndices = new Array();
        for(var j = 0;j<_indices.length;j+=3){
            var p1 = [ 
                       (pos[_indices[j+0]*3+0] + pos[_indices[j+1]*3+0])*0.5 ,
                       (pos[_indices[j+0]*3+1] + pos[_indices[j+1]*3+1])*0.5 ,
                       (pos[_indices[j+0]*3+2] + pos[_indices[j+1]*3+2])*0.5
                   ];
           var p2 = [ 
                       (pos[_indices[j+1]*3+0] + pos[_indices[j+2]*3+0])*0.5 ,
                       (pos[_indices[j+1]*3+1] + pos[_indices[j+2]*3+1])*0.5 ,
                       (pos[_indices[j+1]*3+2] + pos[_indices[j+2]*3+2])*0.5
                   ];
           var p3 = [ 
                       (pos[_indices[j+2]*3+0] + pos[_indices[j+0]*3+0])*0.5 ,
                       (pos[_indices[j+2]*3+1] + pos[_indices[j+0]*3+1])*0.5 ,
                       (pos[_indices[j+2]*3+2] + pos[_indices[j+0]*3+2])*0.5
                   ];
          p1 = normalize(p1);
          p2 = normalize(p2);
          p3 = normalize(p3);
          var i0,i1,i2,a,b,c;
          i0 = pos.length/3;
          i1 = pos.length/3+1;
          i2 = pos.length/3+2;
          a = _indices[j+0];
          b = _indices[j+1];
          c = _indices[j+2];
          newIndices.push(a);newIndices.push(i2);newIndices.push(i0);
          newIndices.push(b);newIndices.push(i0);newIndices.push(i1);
          newIndices.push(c);newIndices.push(i1);newIndices.push(i2);
          newIndices.push(i0);newIndices.push(i2);newIndices.push(i1);

          pos.push(p1[0]);pos.push(p1[1]);pos.push(p1[2]);
          pos.push(p2[0]);pos.push(p2[1]);pos.push(p2[2]);
          pos.push(p3[0]);pos.push(p3[1]);pos.push(p3[2]);

        }
        _indices = newIndices;

    }



    gl.bindBuffer(gl.ARRAY_BUFFER,sphereBuffer);
    gl.bufferData(gl.ARRAY_BUFFER,new Float32Array(pos),gl.STATIC_DRAW);
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER,sphereIndexBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER,new Uint16Array(_indices),gl.STATIC_DRAW);

    sphereIndexBuffer.num = _indices.length;

}

Answer 2

Worldwind Java SDK有一个二十面体曲面细分器，移植到javascript应该非常简单。它也属于类似BSD的许可证。

gov.nasa.worldwind.util.GeometryBuilder

http://builds.worldwind.arc.nasa.gov/download.asp

有没有人有一个样本用于在javascript中绘制细分的二十面体，他们能够共享？

2 个答案: