如何使用“处理”在屏幕上绘制完全填充窗口的N * N网格

Question

How to draw an N*N grid on the screen that completely fills the window. Suppose n=8.

My code is like that:

boolean[][] rects;
void setup ()
{
size(300,300);
rects = new boolean[100][100];
fill(0);

}

void draw (){
  background(255);
  for (int r=0; r<100; r++ ){
    for ( int c = 0; c < 100; c++ ){
      if ( rects[r][c] == true ){
        rect( r*3, c*3, 3, 3 );
      }
    }
  }
}

when I run this code I just get a blank white screen. Am I missing something?

Answer 1

Check out this line:

rects = new boolean[100][100];

This creates a 100x100 2d array of boolean values, but they all have the default value of false because you haven't set them to anything.

Then check out this line:

if ( rects[r][c] == true ){
    rect( r*3, c*3, 3, 3 );
}

Here you're checking whether a particular index is true , but you haven't set them to anything other than the default of false . In other words, this if statement never evaluates to true , so your rect() function is never called.

You need to set some of the boolean values to true for this code to do anything.

rects = new boolean[100][100];
rects[50][50] = true;