如何在java中畫一條對角線的圓？

Question

我有一條對角線，從屏幕的左下部分開始到屏幕的右上部分。現在我想畫出一條從距離左下角到右上角100米的距離，這是我的問題。你能給我一些關於這件事的想法嗎？

任何幫助，將不勝感激......

下面的代碼：

public void paint(Graphics g) 
{ 
    super.paint(g); 

    Graphics2D g2d = (Graphics2D) g; 
    g2d.setBackground(Color.white); 

    int x0_pixel = 0; 
    int y0_pixel = 0; 

    int x1_pixel = getWidth(); 
    int y1_pixel = getHeight(); 

    int x0_world = 0; 
    int y0_world = 0; 

    double x1_world = 2000; // meters 
    double y1_world = 1125; // meters 

    double x_ratio = (double) x1_pixel/x1_world; 
    double y_ratio = (double) y1_pixel/y1_world; 

    int xFrom = 0; 
    int yFrom = 0; 

    double xTo = x1_world; 
    double yTo = y1_world; 

    int FromX_pixel = convertToPixelX(xFrom, x_ratio); 
    int FromY_pixel = convertToPixelY(y1_pixel, yFrom, y_ratio); 

    int ToX_pixel = convertToPixelX((int) xTo, x_ratio); 
    int ToY_pixel = convertToPixelY(y1_pixel, (int) yTo, y_ratio); 

    g2d.setColor(Color.RED); 
    g2d.drawLine(FromX_pixel, FromY_pixel, ToX_pixel, ToY_pixel); 

    double theta = Math.atan(yTo/xTo); 

    double len = (int) Math.sqrt(xTo * xTo + yTo * yTo); 

    int interval = 100; 

    for (int distance = xFrom; distance < len; distance += interval) 
    { 
     double distance_x = (int) Math.cos(theta * distance); 
     double distance_y = (int) Math.sin(theta * distance); 

     int x_circle_pixel = convertToPixelCircleX(FromX_pixel, distance_x); 
     int y_circle_pixel = convertToPixelCircleY(y1_pixel, distance_y, y_ratio); 

     g2d.drawOval(x_circle_pixel, y_circle_pixel, 10, 10); 
    } 

    Toolkit.getDefaultToolkit().sync(); 
    g2d.dispose(); 

} 

private static int convertToPixelY(int y_offset, int y_world, double y_ratio) 
{ 
    return (int) (y_offset - (y_world * y_ratio)); 
} 

private static int convertToPixelX(int x_world, double ratio) 
{ 
    return (int) (x_world * ratio); 
} 

private static int convertToPixelCircleY(int y_offset, double distance, double y_ratio) 
{ 
    return (int) (y_offset - (distance * y_ratio)); 
} 

private static int convertToPixelCircleX(int x_world, double distance_x) 
{ 
    return (int) (x_world * distance_x); 
} 

Answer 1

看看你的部分，我認爲這是錯誤所在。

final double cosTheta = Math.cos(theta); 
final double sinTheta = Math.sin(theta); 

for (int distance = xFrom; distance < len; distance += interval) { 

    double distance_x = distance * cosTheta; 
    double distance_y = distance * sinTheta; 

    //int x_circle_pixel = convertToPixelCircleX(FromX_pixel, distance_x); 
    //int y_circle_pixel = convertToPixelCircleY(y1_pixel, distance_y, y_ratio); 
    int x_circle_pixel = convertToPixelX((int) distance_x, x_ratio); 
    int y_circle_pixel = convertToPixelY(y1_pixel, (int) distance_y, y_ratio); 

    g2d.drawOval(x_circle_pixel, y_circle_pixel, 10, 10); 
}