pakt08

See /software/p5js/pakt-februari/pakt08/ for a JavaScript version and /software/supercollider/februari-pakt/pakt08/ for accompanying sound code.

#include "cinder/app/App.h"
#include "cinder/cairo/Cairo.h"

using namespace ci;
using namespace ci::app;
using namespace std;

const int WIDTH= 640;
const int HEIGHT= 480;

class pakt08App : public App {
public:
  void setup();
  void draw();
  int n;
  float w, h;
  float d, speed, spread, theta;
  vector<vec2> points;
};

void pakt08App::setup() {
  n= 25;
  d= 0.0001f;
  speed= 0.00002f;
  spread= 2.0f;
  theta= 0.0f;
  for(int i= 0; i<n; i++) {
    points.push_back(getWindowCenter());
  }
  w= getWindowWidth();
  h= getWindowHeight();
}

void pakt08App::draw() {
  cairo::Context ctx(cairo::createWindowSurface());
  ctx.setFillRule(1);

  ctx.setSourceRgb(0, 0, 0);
  ctx.paint();
  ctx.moveTo(getWindowCenter());
  //ctx.setLineWidth(10.0f);
  ctx.setSourceRgb(1.0f, 0, 0);
  for(size_t i= 0; i<points.size(); i++) {

    float c= cos(theta+(i*d));
    float s= sin(theta+(i*d));
    float x= (points[i].x/w)*2-1;
    float y= (points[i].y/h)*2-1;
    vec2 v= vec2(
      (((c*x)-(s*y))*0.5+0.5)*w+spread,
      (((c*y)+(s*x))*0.5+0.5)*h+spread
    );
    points[i]= v;
    //ctx.circle(v, 50);
    ctx.lineTo(v);
    theta= theta+speed;
  }
  ctx.fill();
}

CINDER_APP(pakt08App, Renderer2d, [&]( App::Settings *settings ) {
  settings->setWindowSize( WIDTH, HEIGHT );
  settings->setResizable( false );
})