Having trouble with Draw() Can't get fill to change the color of a rect()

dadougler

Im playing around with a knights tour program. I have some code to draw out a chess board. In Draw() im stepping through a 2d array and checking for a value of 1. When 1 is found it should change the fill color to green. It functions correctly if I hard code the 1 into the matrix, but if I set the value to 1 with a MousePressed it wont change colors. When I try to set background(255) to refresh, it just makes the window white and the board doesn't draw.

        int xCur,yCur,x,y,rWidth,rHeight,count;
        int rows = 8;
        int cols = 8;

        int[][] boardArray = { {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0},
                               {0, 0, 0, 0, 0, 0, 0, 0}};
        void setup(){
          size(600,600);
          x=1;
          y=1;
          count=1;
          rWidth=width/8;
          rHeight=height/8;
        }

        void draw(){
          //background(255);
          findMove();
          for(int i = 0; i < rows; i++){
            for(int j = 0; j < cols; j++){
              count++; // counting number of board tiles
              if(count % 2==0){  // toggle tile colors black and white
                fill(255);
              } else {
                fill(0);
              }
              if(boardArray[i][j] == 1){ // color green if 1 is found
                fill(0,255,0);
                println("Detected");
              }
              rect(x,y,rWidth,rHeight);
              y+=rHeight;
            }
            y=1;
            x+=rWidth;
            count++;  //offset tile pattern
          }


        }

        void findMove(){
          xCur = 0;
          yCur = 0;
          if(boardArray[xCur+2][yCur+1] == 0){
            //boardArray[xCur+2][yCur+1]=1;  //this will turn on a green tile if uncommented
          }
        }

        void mousePressed(){
          println("Pressed");
          boardArray[1][1]=1; // cannot get this line of code to work

        }

PhiLho

You don't reset the variables after draw(), so x, y, count go to draw unseen sections of the sketch... This is visible if you uncomment the background() call: the first frame probably draw correctly the checkboard, but it is then erased, and the further rect() calls are way beyond the area.

Using println() of values is also useful when debugging.

Improvement proposal: compute x and y from i and j, thus they will be automatically reset. Or just avoid declaring them global (they are used in only one function), declare them at the start of draw().