JS1k: The JavaScript code golfing competition

function f(a){for(a/=1e3,c.clearRect(0,0,W,H),c.fillStyle="#FFF",o=~~(a/(M>1?9:2)*W)%W,Z[0]=[],i=1;i<4;++i)for(j=0;j<W;++j)k=j-o,k<0&&(k+=W),x=k/i|0,y=Z[i][j]/i,Z[0][x]<y||(Z[0][x]=y);for(i=W;i;){if(!(M%2)){for(X=[],Y=[],z=l=0,j=3;j--;i--)k=i-(M>1?o:0),k<0&&(k+=W),k&&(X[j]=k,Y[j]=Math.tan(i%99*i+a)*H/8+H/8,Y[j]>z&&(z=Y[l=j]));Y[l]>Z[0][i]&&(Y[l]=Z[0][i])}for(c.beginPath(),j=3;j--;)M%2?(k=i-(M>1?o:0),k<0&&(k+=W),k&&(z=Math.tan(i%99*i+a)*H/8+H/8,z>Z[0][i]&&(c.fillRect(k,z,2,2),z=Z[0][i]),c.lineTo(k,z)),i--):c.lineTo(X[j],Y[j]);c.fill()}requestAnimationFrame(f)}for(R=Math.random,W=a.width,H=a.height,a.style.background="#000",Z=[],i=1;i<4;++i)for(Z[i]=[],x=y=0,j=0;j<W;++j)j==x&&(x+=R()*W/8+W/8|0,y=y?0:R()*H/4+H/4),Z[i][j]=H-y;M=0,a.onclick=function(){++M,M>3&&(M=0)},f();

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