SOLVED: Noob Cellular Automata question:

beginners
#1

I’m trying to write one of Daniel Shiffman’s CA from Processing into oF, but I’m having difficulty rendering to the screen.
Here’s my Game of Life class:

  
#include "GOL.h"  
  
GOL::GOL() {  
      
    init();  
}  
  
void GOL::init() {  
      
    for (int i =1;i < cols-1;i++) {  
        for (int j =1;j < rows-1;j++) {  
            board.push_back(rows * cols);  
            board[i * cols + j] = ofRandom(2);  
        }  
    }   
}  
  
void GOL::generate() {  
    vector<int> next(rows * cols);  
      
    // Loop through every spot in our 2D array and check spots neighbors  
    for (int x = 0; x < cols; x++) {  
        for (int y = 0; y < rows; y++) {  
              
            // Add up all the states in a 3x3 surrounding grid  
            int neighbors = 0;  
            for (int i = -1; i <= 1; i++) {  
                for (int j = -1; j <= 1; j++) {  
                    neighbors += board[((x+i+cols)%cols) * cols + ((y+j+rows)%rows)];  
                }  
            }  
              
            // A little trick to subtract the current cell's state since  
            // we added it in the above loop  
            neighbors -= board[x * cols + y];  
              
            // Rules of Life  
            if      ((board[x * cols + y] == 1) && (neighbors <  2)) next[x * cols + y] = 0;           // Loneliness  
            else if ((board[x * cols + y] == 1) && (neighbors >  3)) next[x * cols + y] = 0;           // Overpopulation  
            else if ((board[x * cols + y] == 0) && (neighbors == 3)) next[x * cols + y] = 1;           // Reproduction  
            else                                            next[x * cols + y] = board[x * cols + y];  // Stasis  
        }  
    }  
      
    // Next is now our board  
    board = next;  
      
}  
  
void GOL::display() {  
    for ( int i = 0; i < cols;i++) {  
        for ( int j = 0; j < rows;j++) {  
            if (board[i * cols + j] == 1) {  
                col.set(255);  
                ofSetColor(col);  
            }  
            else {  
                col.set(0, 255, 0);  
                ofSetColor(col);  
            }  
            ofRect(i * w, j * w, w , w);  
        }  
    }  
}

When I build and run I get a green screen. I think the issue may reside in my display method? I’d be very grateful if someone could point me in the right direction.
Thanks.

#2

test.h

  
  
#pragma once  
  
#include "ofMain.h"  
  
class testApp : public ofBaseApp{  
  
	public:  
		void setup();  
		void update();  
		void draw();  
  
		void keyPressed  (int key);  
		void keyReleased(int key);  
		void mouseMoved(int x, int y );  
		void mouseDragged(int x, int y, int button);  
		void mousePressed(int x, int y, int button);  
		void mouseReleased(int x, int y, int button);  
		void windowResized(int w, int h);  
		void dragEvent(ofDragInfo dragInfo);  
		void gotMessage(ofMessage msg);  
    int neighbors(int x, int y);  
    int sx, sy;   
    float density ;   
    int world[640][360][2];  
};

test.cpp

  
  
#include "testApp.h"  
  
//--------------------------------------------------------------  
void testApp::setup(){  
     
      
        ofSetFrameRate(12);  
        sx = ofGetWidth();  
        sy = ofGetHeight();  
    density = 0.5;  
          
        // Set random cells to 'on'   
        for (int i = 0; i < sx * sy * density; i++) {   
            int x = int(ofRandom(sx));  
            int y = int(ofRandom(sy));  
            world[x][y][1] = 1;   
        }   
       
      
      
    // Count the number of adjacent cells 'on'   
}  
//--------------------------------------------------------------  
  
int testApp::neighbors(int x, int y) {   
    return world[(x + 1) % sx][y][0] +   
    world[x][(y + 1) % sy][0] +   
    world[(x + sx - 1) % sx][y][0] +   
    world[x][(y + sy - 1) % sy][0] +   
    world[(x + 1) % sx][(y + 1) % sy][0] +   
    world[(x + sx - 1) % sx][(y + 1) % sy][0] +   
    world[(x + sx - 1) % sx][(y + sy - 1) % sy][0] +   
    world[(x + 1) % sx][(y + sy - 1) % sy][0];   
}   
  
  
//--------------------------------------------------------------  
  
  
//--------------------------------------------------------------  
void testApp::draw(){  
     
    ofBackground(0);   
      
    // Drawing and update cycle   
    for (int x = 0; x < sx; x=x+1) {   
        for (int y = 0; y < sy; y=y+1) {   
            if (world[x][y][1] == 1) {  
            
                world[x][y][0] = 1;   
                ofSetColor(255);  
/*  
//Black and White is boring uncomment for more fun!  
  
                ofColor c;  
                int hue = ofMap(y, 0, sy, 20, 200);  
                c.setHsb(hue,255, 255);  
                ofSetColor(c);  
  
*/  
                ofRect(x , y, 1 , 1);    
            }   
            if (world[x][y][1] == -1) {   
                world[x][y][0] = 0;   
            }   
            world[x][y][1] = 0;   
        }   
    }   
    // Birth and death cycle   
    for (int x = 0; x < sx; x=x+1) {   
        for (int y = 0; y < sy; y=y+1) {   
            int count = neighbors(x, y);   
            if (count == 3 && world[x][y][0] == 0) {   
                world[x][y][1] = 1;   
            }   
            if ((count < 2 || count > 3) && world[x][y][0] == 1) {   
                world[x][y][1] = -1;   
            }   
        }   
    }   
  
}
#3

Thanks for this. I have one issue. I see you use a three dimensional array for the CA space. My CA space must be a one dimensional vector as I intend to pass the vector into a Pure Data array via ofxPd.

#4

Fixed: the init() method should look like this:

  
void GOL::init() {  
      
    for (int i =0; i < cols; i ++) {  
        for (int j =0; j < rows; j ++) {  
            board.push_back(rows * cols);  
            board[i * cols + j] = ofRandom(2);  
        }  
    }   
}