contourfinder.pde

import gab.opencv.*;

PImage src;
OpenCV opencv;
int thresh = 70;
float approx = 0.02;
float minArea = 1.0;

ArrayList<Contour> contours;
ArrayList<Contour> polygons;

void setup() {
  src = loadImage("shark_4.png"); 
  size(1080, 720);
  opencv = new OpenCV(this, src);

  doContour();  
}

void doContour() {
  opencv.gray();
  opencv.threshold(thresh);
  contours = opencv.findContours();
  
  for (Contour contour : contours) {
    contour.setPolygonApproximationFactor(contour.getPolygonApproximationFactor() * approx);
  }
  println("found " + contours.size() + " contours");
}

void draw() {
  blendMode(NORMAL);
  image(src, 0, 0);

  if (keyPressed) {
    if (key == 'w') {
      thresh++;
    } else if (key == 's') {
      thresh--;
    }
    
    if (key == 'i') {
      approx -= 0.01;
    } else if (key == 'k') {
      approx += 0.01;
    }
    
    if (key == 'o') {
      minArea++;
    } else if (key == 'l') {
      minArea--;
    }
    
    thresh = constrain(thresh, 0, 255);
    approx = constrain(approx, 0.0, 1.0);
    minArea = constrain(minArea, 1.0, 1000.0);
    
    if (key == 'w' || key == 's' || key == 'i' || key == 'k' || key == 'o' || key == 'l') {
      doContour();
      println(thresh + " " + approx + " " + minArea);
    }
  }

  noFill();
  
  blendMode(ADD);

  for (Contour contour : contours) {
    if (contour.area() >= minArea) {
      strokeWeight(1);
      stroke(0, 255, 0);
      beginShape();
      for (PVector point : contour.getPoints()) {
        vertex(point.x, point.y);
      }
      endShape();
      
      strokeWeight(3);
      stroke(255, 0, 0);
      beginShape();
      for (PVector point : contour.getPolygonApproximation().getPoints()) {
        vertex(point.x, point.y);
      }
      endShape();
    }
  }
}