java - 咖啡厅墙错觉

Question

这是我的代码的预期输出:

这是我的代码:

import java.awt.*;

public class CafeWall
{
    final static int MORTAR = 2;
    final static int WIDTH  = 650;
    final static int HEIGHT = 400;

    public static void main( String[] args )
    {
        StdDraw.setCanvasSize(WIDTH, HEIGHT);
        StdDraw.setXscale(0, WIDTH);
        StdDraw.setYscale(0, HEIGHT);

 // Change from Color.GRAY to change background color.
        StdDraw.setPenColor( Color.GRAY );
        StdDraw.filledRectangle(WIDTH/2, HEIGHT/2, WIDTH/2, HEIGHT/2);

 drawRow(    0, 378, 4, 20 );
 drawRow(   50, 300, 5, 30 );

 drawGrid(  10, 36, 4, 25, 0 );

 drawGrid( 250, 40,  3, 25, 10 );

 drawGrid( 425, 2, 5, 20, 10 );

 drawGrid( 400, 234,  2, 35, 35 );
    }

    // Draw a row of squares, the total number of squares is pairs * 2
    // (x, y) is the lower left corner of the first box
    public static void drawRow( int x, int y, int pairs, int size )
    {
      StdDraw.setPenColor(Color.BLACK);
      StdDraw.filledRectangle(x, y, size, size);
      StdDraw.setPenColor(Color.BLUE);
      StdDraw.line(x, y, x+size, y+size);
      StdDraw.line(x, y+size, x+size, y);
      StdDraw.setPenColor(Color.WHITE);
      StdDraw.filledRectangle(x+size, y, size, size);
    }

    // Draw a grid of 2 * pairs rows
    public static void drawGrid( int x, int y, int pairs, int size, 
     int offset )
    {
      int startingX = x;
      for(int line = 1; line <= pairs; line++) {
        if(line % 2 ==1) { //if line is odd
          x = startingX;
        } else { //else line is even and must be shifted by offset specified
          x = startingX + offset;
        }
        for(int i = 1; i <= pairs; i++) {
          drawRow(x, y, pairs, size);
          x = x + 2*size;
        }

        y = y + size + MORTAR;
      }
    }


}

问题:

• 我的行没有正确偏移
• 我的蓝色“x”没有出现。

我已经盯着这个看了好几个小时了。我似乎无法弄清楚我哪里出错了。谁能提供一些指导？

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(补充说明)对于那些想知道的人来说，这是这段代码的实际输出:

Answer 1

drawRow() 有两个重要问题:

1. 您没有正确地将 drawRow 中的矩形居中
2. 你没有在 drawRow 中正确地重复对

这个方法应该是这样的:

public static void drawRow( int x, int y, int pairs, int size ) {
    // loop for each pair.
    for (int i = 0; i < pairs; i++) {
        StdDraw.setPenColor(Color.BLACK);
        // Note the correct centering of the rectangles
        StdDraw.filledRectangle(x + size/2, y + size/2, size / 2, size/2);
        StdDraw.setPenColor(Color.BLUE);
        StdDraw.line(x, y, x+size, y+size);
        StdDraw.line(x, y+size, x+size, y);
        StdDraw.setPenColor(Color.WHITE);
        // Note the correct centering of the rectangles
        StdDraw.filledRectangle(x+size+size/2, y + size/2, size / 2, size/2);
        // advance to the next pair.
        x += size * 2;
    }
}

在您的 drawGrid() 方法中，您应该有一个额外的 rows 参数，它指示要绘制多少行。我将该方法修改为如下所示:

public static void drawGrid( int x, int y, int rows, int pairs, int size, 
        int offset )
{
    int startingX = x;
    for(int line = 0; line < rows; line++) {
        x = startingX + (line % 2) * offset;
        drawRow(x, y, pairs, size);

        y = y + size + MORTAR;
    }
}

请注意 (line % 2) * offset 的“巧妙”使用。弄清楚这一点。

把它放在一起，并改变一些行的大小，我有主要的方法调用:

    drawRow(    0, 378, 4, 20 );
    drawRow(   50, 300, 5, 30 );

    // Bottom left
    drawGrid(  10, 36, 4, 4, 20, 0 );

    // bottom mid
    drawGrid( 250, 40, 6, 3, 25, 10 );

    // bottom right
    drawGrid( 425, 2, 10, 5, 16, 8 );

    // top right
    drawGrid( 400, 234, 4, 2, 35, 35 );

我的结果是这样的:

这些与您之前的内容相比并没有太大的变化……只是到处都是一些逻辑。