pubtool4pixi/src/polar.js

Usefultool for PIXI xes project

function getRadius(x,y){
  return Math.sqrt(Math.pow(x,2)+Math.pow(y,2));
}
function getTheta(x,y){
  if( x === 0 && y === 0 ){
    return 0;
  }
  if( x === 0 ){
    if( y > 0 ){
      return Math.PI/2;
    }else{
      return -Math.PI/2;
    }
  }
  return Math.atan(target.y/target.x);
}
function bindPolarProperty(obj, target){
  Object.defineProperty(obj,"theta",{
    get(){
      return obj._theta;
    },
    set(theta){
      target.y = -obj.radius*Math.sin(theta);
      target.x = obj.radius*Math.cos(theta);
      obj._theta = theta;
    }
  });//极坐标角度
  Object.defineProperty(obj,"radius",{
    get(){
      return obj._radius;
    },
    set(radius){
      target.y = -radius*Math.sin(obj.theta);
      target.x = radius*Math.cos(obj.theta);
      obj._radius = radius;
    }
  });//极坐标半径
  obj._theta = getTheta(target.x,target.y);
  obj._radius = getRadius(target.x,target.y);
}
export default bindPolarProperty;