大神帮我看看这行代码的具体含义

function drawCircle(obj,theta,phi,i,j){
obj.circleX = r*Math.sin(theta*i)*Math.sin(phi*j) + 200;
obj.circleY = -r*Math.cos(theta*i) + 200;
obj.circleZ = r*Math.sin(theta*i)*Math.cos(phi*j);
obj.circleTheta = theta*(circleArr.length-i);
obj.circlePhi = phi*j;
obj.bigCircleX = (r+2000)*Math.sin(theta*i)*Math.sin(phi*j) + 200;
obj.bigCircleY = -(r+2000)*Math.cos(theta*i) + 200;
obj.bigCircleZ = (r+2000)*Math.sin(theta*i)*Math.cos(phi*j);
obj.maxX = obj.bigCircleX;
obj.maxY = obj.bigCircleY;
obj.maxZ = obj.bigCircleZ;
obj.maxTheta = obj.circleTheta;
obj.maxPhi = obj.circlePhi;
}