tomohiro_test_frac

<canvas id="canvas" width="512" height="512"></canvas>
<script type="text/javascript">
    function init() {
        function frac(x, y, z) {
            function fraccore(x)
            {
                ox = x;
                var scale = 1;
                for(i=0; i<6; i++)
                {
                    x*=3;
                    scale*=3;
                    flx = Math.floor(x);
                    x -= flx;
                    if(!( flx==0 || flx==2 ))
                    {
                        if(x<1.5)
                        {
                            ox -= 1/scale;
                        }else
                        {
                            ox += 1/scale;
                        }
                    }
                }

                return ox;
            }

            x = fraccore(x)-0.5;
            y = fraccore(y)-0.5;
            z = fraccore(z)-0.5;
            return [x*4*x*x, y*4*y*y, z*4*z*z+1.5, (z*4*z*z+0.5)*255];
        }
        var canvas=document.getElementById("canvas"),
            context=canvas.getContext("2d"),
            imageData=context.getImageData(0, 0, 512, 512),
            buffer=imageData.data,
            zbuffer=[512*512],
            interval,
            steps=0,
            render=function () {
                var point, i, x, y, z, xp, yp, pos;

                for (i=0; i<50000; i++) {
                    x=Math.random();
                    y=Math.random();
                    z=Math.random();
                    point = frac(x, y, z);
                    xp=
                        Math.floor(
                            ((point[0])*512)/point[2])+
                        256;
                    yp=
                        Math.floor(
                            ((point[1])*512)/point[2])+
                        256;
                    if (
                            (xp>=0)&&
                            (xp<512)&&
                            (yp>=0)&&
                            (yp<512)&&
                            (point[2]<zbuffer[pos=yp*512+xp]))
                    {
                        zbuffer[pos]=point[2];
                        buffer[pos*4+1]=point[3];
                        buffer[pos*4+3]=255;
                    }
                }
                context.putImageData(imageData, 0, 0);
                steps++;
                if (steps>1024) {
                    window.clearInterval(interval);
                }
            };

        for (i=0; i<512*512; i++) {
            zbuffer[i]=10000000000;
        }
        interval=window.setInterval(render, 0);
    }
    init();
</script>