CVImage and PixelFlow in Processing

Posted by bryan

This is a quick demonstration of using the CVImage library, from the book, Pro Processing for Images and Computer Vision with OpenCV, and the PixelFlow library from Thomas Diewald.
 
Here is the video documentation.

The full source code is below with one additional class.

Main Processing sketch

import cvimage.*;
import processing.video.*;
import com.thomasdiewald.pixelflow.java.DwPixelFlow;
import com.thomasdiewald.pixelflow.java.fluid.DwFluid2D;
import org.opencv.core.*;
import org.opencv.objdetect.CascadeClassifier;
import org.opencv.objdetect.Objdetect;
 
// Face detection size
final int W = 320, H = 180;
Capture cap;
CVImage img;
CascadeClassifier face;
float ratio;
DwFluid2D fluid;
PGraphics2D pg_fluid;
MyFluidData fluidFunc;
 
void settings() {
  size(1280, 720, P2D);
}
 
void setup() {
  background(0);
  System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
  println(Core.VERSION);
  cap = new Capture(this, width, height);
  cap.start();
  img = new CVImage(W, H);
  face = new CascadeClassifier(dataPath("haarcascade_frontalface_default.xml"));
  ratio = float(width)/W;
 
  DwPixelFlow context = new DwPixelFlow(this);
  context.print();
  context.printGL();
  fluid = new DwFluid2D(context, width, height, 1);
  fluid.param.dissipation_velocity = 0.60f;
  fluid.param.dissipation_density = 0.99f;
  fluid.param.dissipation_temperature = 1.0f;
  fluid.param.vorticity = 0.001f;
 
  fluidFunc = new MyFluidData();
  fluid.addCallback_FluiData(fluidFunc);
  pg_fluid = (PGraphics2D) createGraphics(width, height, P2D);
  pg_fluid.smooth(4);
}
 
void draw() {
  if (!cap.available()) 
    return;
  background(0);
  cap.read();
  cap.updatePixels();
 
  img.copy(cap, 0, 0, cap.width, cap.height, 
    0, 0, img.width, img.height);
  img.copyTo();
 
  Mat grey = img.getGrey();
  MatOfRect faces = new MatOfRect();
 
  face.detectMultiScale(grey, faces, 1.15, 3, 
    Objdetect.CASCADE_SCALE_IMAGE, 
    new Size(60, 60), new Size(200, 200));
  Rect [] facesArr = faces.toArray();
  if (facesArr.length > 0) {
    fluidFunc.findFace(true);
  } else {
    fluidFunc.findFace(false);
  }
  for (Rect r : facesArr) {
    float cx = r.x + r.width/2.0;
    float cy = r.y + r.height/2.0;
    fluidFunc.setPos(new PVector(cx*ratio, cy*ratio));
  }
  fluid.update();
  pg_fluid.beginDraw();
  pg_fluid.background(0);
  pg_fluid.image(cap, 0, 0);
  pg_fluid.endDraw();
  fluid.renderFluidTextures(pg_fluid, 0);
  image(pg_fluid, 0, 0);
  pushStyle();
  noStroke();
  fill(0);
  text(nf(round(frameRate), 2, 0), 10, 20);
  popStyle();
  grey.release();
  faces.release();
}

The class definition of MyFluidData

private class MyFluidData implements DwFluid2D.FluidData {
  float intensity;
  float radius;
  float temperature;
  color c;
  boolean first;
  boolean face;
  PVector pos;
  PVector last;
 
  public MyFluidData() {
    super();
    intensity = 1.0f;
    radius = 25.0f;
    temperature = 5.0f;
    c = color(255, 255, 255);
    first = true;
    pos = new PVector(0, 0);
    last = new PVector(0, 0);
    face = false;
  }
 
  public void findFace(boolean f) {
    face = f;
  }
 
  public void setPos(PVector p) {
    if (first) {
      pos.x = p.x;
      pos.y = p.y;
      last.x = pos.x;
      last.y = pos.y;
      first = false;
    } else {
      last.x = pos.x;
      last.y = pos.y;
      pos.x = p.x;
      pos.y = p.y;
    }
  }
 
  @Override
    public void update(DwFluid2D f) {
 
    if (face) {
      float px = pos.x;
      float py = height - pos.y;
      float vx = (pos.x - last.x) * 10.0f;
      float vy = (pos.y - last.y) * -10.0f;
      c = color(random(100, 255), random(100, 255), random(50, 100));
      f.addVelocity(px, py, radius, vx, vy);
      f.addDensity (px, py, radius, 
        red(c)/255, green(c)/255, blue(c)/255, 
        intensity);
      f.addTemperature(px, py, radius, temperature);
    }
  }
}