如何在循环路径中的物体移动？ [英] how to make an object move in circular path?

问题描述

考虑两个圆圈（0,0）为中心，以110和210分别半径...

即我有中心为（0,0）和1圈半径110和2圈半径210。
现在我需要的在移动这两个圆之间的物体tball

下面是我的code -

 公共无效的run（）{        而（isitok ==真）{
            //进行绘图
            如果（！holder.getSurface（）。的isValid（））{
                继续;
            }
            帆布帆布= holder.lockCanvas（）;
            canvas.drawARGB（255，150，150，10）;            //的System.out.println（画布上的矩阵 - + canvas.getm））;
            涂料P =新的油漆（）;            // canvas.drawBitmap（tball，（X  -  tball.getWidth（））/ 2，
            //（γ -  tball.getHeight（））/ 2，p）的;            p.setStyle（Paint.Style.STROKE）;
            p.setColor（Color.WHITE）;
            p.setColor（Color.parseColor（＃0101DF））;            canvas.drawCircle（canvas.getWidth（）/ 2，
                    canvas.getHeight（）/ 2，60，p）的;
            canvas.drawCircle（canvas.getWidth（）/ 2，
                    canvas.getHeight（）/ 2，110，p）的;            浮X =（canvas.getWidth（）/ 2） - （tball.getWidth（）/ 2）;
            浮Y =（canvas.getHeight（）/ 2） -  110 +（110  -  60）/ 2
                     - （tball.getHeight（）/ 2）;            canvas.drawBitmap（tball，X，Y，P）;            浮movingpts [];            holder.unlockCanvasAndPost（画布）;
        }
    }
 

解决方案

圈子坐标

  X = MX + R * COS（角度）
Y = MY + R *罪（角）
 

，其中（MX，MY）是中心或圆的中点，R是半径。对于屏幕坐标，有时最好使用

  Y = MY  -  R *罪（角）
 

要获得与盘的方向数学约定相一致的角度。

consider two circles with (0,0) as center and 110 and 210 as radius respectively...

i.e i have CENTER as (0,0) and CIRCLE 1 radius as 110 and CIRCLE 2 radius as 210. Now i need to move an object tball in between these two circles.

Here is my code--

public void run() {

        while (isitok == true) {
            // perform drawing
            if (!holder.getSurface().isValid()) {
                continue;
            }
            Canvas canvas = holder.lockCanvas();
            canvas.drawARGB(255, 150, 150, 10);

            // System.out.println("Canvas matrix  -" + canvas.getm));
            Paint p = new Paint();

            // canvas.drawBitmap(tball, (x - tball.getWidth()) / 2,
            // (y - tball.getHeight()) / 2, p);

            p.setStyle(Paint.Style.STROKE);
            p.setColor(Color.WHITE);
            p.setColor(Color.parseColor("#0101DF"));

            canvas.drawCircle(canvas.getWidth() / 2,
                    canvas.getHeight() / 2, 60, p);
            canvas.drawCircle(canvas.getWidth() / 2,
                    canvas.getHeight() / 2, 110, p);

            float x = (canvas.getWidth() / 2) - (tball.getWidth() / 2);
            float y = (canvas.getHeight() / 2) - 110 + (110 - 60) / 2
                    - (tball.getHeight() / 2);

            canvas.drawBitmap(tball, x, y, p);

            float movingpts[];

            holder.unlockCanvasAndPost(canvas);
        }
    }

解决方案

Circle coordinates are

X = MX + R * cos( angle )
Y = MY + R * sin( angle )

where (MX,MY) is the center or midpoint of the circle and R the radius. For screen coordinates it is sometimes better to use

Y = MY - R * sin( angle )

to get the angle consistent with mathematical conventions on circle orientation.

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