模型按一个圈摆放（10等分）

var R = 320;
 function setPosition(){
            pivot2.position.x  = -    Math.sin(Math.PI/5)*R;
            pivot2.position.z = Math.cos(Math.PI/5)*R;
            pivot2.rotation.z = -Math.PI/10*3;

            pivot3.position.x  = 0;
            pivot3.position.z = R;
            pivot3.rotation.z = -Math.PI/2;

            pivot4.position.x  = Math.sin(Math.PI/5)*R;
            pivot4.position.z = Math.cos(Math.PI/5)*R;
            pivot4.rotation.z = Math.PI/10*13;

            pivot5.position.x  = Math.sin(Math.PI/10*4)*R;
            pivot5.position.z = Math.cos(Math.PI/10*4)*R;
            pivot5.rotation.z = Math.PI/10*11;

            pivot6.position.x  = Math.sin(Math.PI/10*4)*R;
            pivot6.position.z = -Math.cos(Math.PI/10*4)*R;
            pivot6.rotation.z = -Math.PI/10*11;

            pivot7.position.x  = Math.sin(Math.PI/5)*R;
            pivot7.position.z = -Math.cos(Math.PI/5)*R;
            pivot7.rotation.z = -Math.PI/10*13;

            pivot8.position.x  = 0;
            pivot8.position.z = -R;
            pivot8.rotation.z = Math.PI/2;

            pivot9.position.x  = -Math.sin(Math.PI/5)*R;
            pivot9.position.z = -Math.cos(Math.PI/5)*R;
            pivot9.rotation.z = Math.PI/10*3;

            pivot10.position.x  = -Math.sin(Math.PI/10*4)*R;
            pivot10.position.z = -Math.cos(Math.PI/10*4)*R;
            pivot10.rotation.z = Math.PI/10*1;

            pivot.position.x  = -Math.sin(Math.PI/10*4)*R
            pivot.position.z = Math.cos(Math.PI/10*4)*R
            pivot.rotation.z = -Math.PI/10;
            //
        }