我有兩個同心圓,它們的中心位於(centerX,centerY)。內圓的半徑爲100,外圓的半徑爲400.如果在內圓的圓周上取一個點,我可以畫一條從中心到該點的直線。我們稱之爲x1,y1)。我現在想要將該半徑延續到外部同心圓並計算該外部點的位置(x2,y2)。在動作腳本中找到一個外部同心圓上的點
我正在添加一個3px'點'來顯示x1,y1在屏幕上的位置。 (Subquestion:我看不出它......不知道爲什麼。)
這就是我想:
var x1:Number = 100;
var y1:Number = 50;
var x2:Number;
var y2:Number;
var centerX:Number = 200;
var centerY:Number = 200;
var myAngle:Number = Math.atan2(y1 - centerY, x1-centerX);
//x2 = x1 + 300 * Math.cos(myAngle);
//y2 = y1 + 300 * Math.sin(myAngle);
x2 = centerX + Math.cos(myAngle) * 400;
y2 = centerY + Math.sin(myAngle) * 400;
trace("x2,y2 = " + x2 + "," + y2);
var myCenterPoint:Sprite = new Sprite();
this.graphics.lineStyle(3,0x00ff00); //green, center point
this.graphics.moveTo(centerX, centerY);
graphics.drawCircle(centerX,centerY,5);
addChild(myCenterPoint);
var myInnerCirclePointMarker:Sprite = new Sprite();
this.graphics.lineStyle(3,0x0000FF); //blue, inner circle circumf. marker
this.graphics.moveTo(x1, y1);
graphics.drawCircle(x1,y1,5);
addChild(myInnerCirclePointMarker);
trace("x2,y2 = " + x2 + "," + y2);
var myOuterCirclePointMarker:Sprite = new Sprite();
this.graphics.lineStyle(3,0xff0000); //red, outer circle circumf. marker
myOuterCirclePointMarker.graphics.drawCircle(x2,y2,5);
addChild(myOuterCirclePointMarker);
this.graphics.moveTo(centerX, centerY);
this.graphics.lineTo(x2, y2); //draw line, which should go through
//x1,y1 and end at x2,y2
我不認爲這是要正確地告訴我外沿着圓的所有360度點。
謝謝。
此外,就我所知,您的初始值x1,y1不在內圈上。你仍然會從atan2中得到一個角度,但是你的問題指出座標應該在內圈上。 – sirlark 2011-05-29 13:30:53