java - 旋转画线 Java Applet

Question

我创建了一个 Java Applet，它有一个抛物线图，但我的抛物线是颠倒的？如何旋转我的绘图线？

我扩展和实现的内容:

public class Parabola extends Applet implements AdjustmentListener {

    //bunch of my code is in here ...

    public void paint(Graphics g) {

        //bunch of my code in here ...

        for (int i = 0; i <= 999; i++) {                           
            y1 = (int)(p[i] * 100) + 100;
            y2 = (int)(p[i+1] * 100) + 100;              
            g.drawLine(i + 20, y1, (i + 1) + 20, y2); //its upside down, needs to be rotated                      
        }
    }
}

Answer 1

其实我是从this里算出来的网站——基本上是三角学。

但是，如果有更简单的方法，请分享。

我们使用:

X2 =X1*cos(theta)-Y1*sin(theta);
Y2 =X1*sin(theta)+Y1*cos(theta); 

原行:

g.drawLine(200,200,x1+200,200-y1);

旋转线:

g.drawLine(200,200,x2+200,200-y2);