在java中绘制sin（x）图 [英] Drawing the graph of sin(x) in java

问题描述

我目前正试图在java中绘制sin（x）图。根据我的任务指示，我只需要使用drawLine（）作为绘制图形的方法。我似乎无法弄清楚如何正确设置我的y值。现在我所拥有的是一个while循环，用于逐像素地绘制线条，但无法设法使y值正确。这是我到目前为止。

  public class GraphJComponent extends JComponent {
 public void paintComponent（Graphics g）{ 
颜色轴=新颜色（128，128，128）; 
 g.setColor（axis）; 
 
 int xShift = getWidth（）/ 50; 
 int xShift2 = getWidth（）/ 100; 
 int yShift = getHeight（）/ 10; 
 int yShift2 = getHeight（）/ 17; 
 
 g.drawLine（xShift，yShift，xShift，getHeight（） -  yShift）; 
 g.drawLine（xShift，getHeight（）/ 2，getWidth（） -  xShift，getHeight（）/ 2）; 
 
 g.drawString（0，xShift + xShift2，getHeight（）/ 2 + yShift2）; 
 g.drawString（1，xShift + xShift2，yShift  - （yShift2 / 4））; 
 g.drawString（ -  1，xShift + xShift2，getHeight（） -  yShift + yShift2）; 
 g.drawString（\\\π，getWidth（）/ 2，getHeight（）/ 2 + yShift2）; 
 g.drawString（2+\\\π，getWidth（） - （2 * xShift），getHeight（）/ 2 + yShift2）; 
 
颜色线=新颜色（255，0，0）; 
 g.setColor（line）; 
 
 int x = xShift; 
 int y = getHeight（）/ 2; 
 
 
 
 
 while（x  x + = 1; 
 
 y = ??; 
 
 
 g.drawLine（x，y，x，y）; 
} 
 
 
 
 
 
 
 
 
 
 
} 
  

}

是的，我知道有无数的事情，我可以整理或简化，这只是一个粗略的草案，本身，我会清理一旦我有一切工作。
我已经尝试了多种方法来设置y值，最接近的我画了一条直线，但它不像本应该弯曲的那样。我能做些什么来正确地设置y值，以便正确绘制[0,2pi]的正弦图？

试图澄清问题：
问题在于改变drawLine函数的y值。基本上，我所做的工作并不能正确地描绘罪的功能，因为我只能想出分数递增它。它看起来像这样：

  / \ 
 / \ / 
 \ / 
  

我得到的最终问题是：如何使它成为我的y坐标将使用适当的y坐标sin（x）图的？换句话说，我怎样才能使它不直，并像sin（x）图应该正确地弯曲。

另一种观察问题的方式是我可以用我的JFrame的像素来正确地缩放sin（x）的y值吗？
感谢您的时间，我感谢您的任何帮助。

减少你的 x 增量，但是我认为你试图在整个 2 * PI >宽度间隔。

使用 y = Math.sin（x * Math.PI * 2 / getWidth（） ）; 在将 x 值插入到 sin 函数中之前，它将缩放您的 x 值。 / p>

I am currently trying to draw the graph of sin(x) in java. I am required by the instructions of my assignment to only use drawLine() as the method of drawing the graph. I can't seem to figure out how to properly set my y value though. Right now what I have is a while loop used in order to draw the line pixel by pixel, but cannot manage to get the y value to be correct. Here is what I have so far.

public class GraphJComponent extends JComponent {
public void paintComponent (Graphics g){
    Color axis = new Color(128, 128, 128);
    g.setColor(axis);

    int xShift = getWidth() / 50;
    int xShift2 = getWidth() / 100;
    int yShift = getHeight() / 10;
    int yShift2 = getHeight() / 17;

    g.drawLine(xShift,yShift,xShift,getHeight() - yShift);
    g.drawLine(xShift, getHeight() / 2, getWidth() - xShift, getHeight() / 2);

    g.drawString("0", xShift + xShift2, getHeight() / 2 + yShift2);
    g.drawString("1", xShift + xShift2, yShift - (yShift2 / 4));
    g.drawString("-1", xShift + xShift2, getHeight() - yShift + yShift2);
    g.drawString("\u03c0", getWidth() / 2, getHeight() / 2 + yShift2);
    g.drawString("2" + "\u03c0", getWidth() - (2 * xShift), getHeight() / 2 + yShift2);

    Color line = new Color (255, 0, 0);
    g.setColor(line);

    int x = xShift;
    int y = getHeight() / 2;




    while (x < getWidth() - xShift){
        x += 1;

        y = ??;


        g.drawLine(x, y, x, y);
    }










}

}

Yes I know there are numerous things that I could tidy up or simplify, this is just a rough draft, per-se, that I will clean up once I have everything working. I have tried multiple methods of getting the y value to properly be set, the closest I got ended up drawing a straight diagonal lines, it wasn't curved like it was supposed to be. What can I do to properly set the y value so that the sin graph from [0, 2pi] will be properly drawn?

To try to clarify the issue: The problem lies in changing the y value of my drawLine function. Basically, what I had working wouldn't draw the sin function properly because I only could figure out to lineraly increment it. It looked something like this:

 /\
/  \  /
    \/

The ultimate question I have is: How can I make it so my y coordinate will scale with the proper y coordinate of the sin(x) graph? In other words, how can I make it "not-straight" and properly curved like the sin(x) graph should.

Another way to look at the issue is how could I properly "scale" the y value of sin(x) with the pixels of my JFrame? Thank you for your time I appreciate any help.

解决方案

Well, David Wallace mentioned in comments that you need to reduce your x increment, but I think you are trying to get 2*PI over the entire width interval.

Use y = Math.sin(x*Math.PI*2/getWidth()); which will scale your x values before plugging them into your sin function.

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