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pakt24

See /software/p5js/pakt-februari/pakt24/ for a JavaScript version and /software/supercollider/februari-pakt/pakt24/ 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 pakt24App : public App {
public:
    void setup();
    void draw();
    cairo::SurfaceImage srfOff;
    cairo::Context ctxOff;
    int index;
    float w, h;
    int n;
};

void pakt24App::setup() {
    srfOff= cairo::SurfaceImage(WIDTH, HEIGHT, false);
    ctxOff= cairo::Context(srfOff);
    ctxOff.setLineWidth(0.1);
    index= 0;
    w= getWindowWidth();
    h= getWindowHeight();
    n= 80;
}

void pakt24App::draw() {
    
    float rx= sin(index*0.0012f);
    float ry= sin(index*0.0022f+1.0f);
    float tx= sin(index*0.0032f+2.0f)+rx;
    float ty= sin(index*0.0042f+3.0f)+ry;
    
    cairo::Context ctx(cairo::createWindowSurface());
    ctxOff.setSourceRgba(1, 1, 1, 0.02);
    ctxOff.paint();
    
    ctxOff.setSourceRgba(0, 0, 0, 1);
    for(int i= 0; i<n; i++) {
        float t= float(i)/n*2*M_PI;
        if(i==0) {
            ctxOff.moveTo((cos((-1.0f/n*2*M_PI)+rx+tx)*0.49f+0.5f)*w, (sin((-1.0f/n*2*M_PI)+ry+ty)*0.49f+0.5f)*h);
        }
        ctxOff.quadTo((sin(t+rx+tx)*0.49f+0.5f)*w, (cos(t+ry+ty)*0.49f+0.5f)*h, (cos(t+rx+tx)*0.49f+0.5f)*w, (sin(t+ry+ty)*0.49f+0.5f)*h);
    }
    ctxOff.stroke();
    index++;
    ctx.copySurface(srfOff, srfOff.getBounds());
}

CINDER_APP(pakt24App, Renderer2d, [&]( App::Settings *settings ) {
    settings->setWindowSize( WIDTH, HEIGHT );
    settings->setResizable( false );
})