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pakt06

See /software/p5js/pakt-februari/pakt06/ for a JavaScript version and /software/supercollider/februari-pakt/pakt06/ 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 pakt06App : public App {
public:
    void setup();
    void draw();
    int n;
    float w, h;
    float theta, speed, spread;
    vector<vec2> points;
};

void pakt06App::setup() {
    n= 50;
    theta= 0;
    speed= 0.00002;
    spread= 1;
    for(int i= 0; i<n; i++) {
        points.push_back(getWindowCenter());
    }
    w= getWindowWidth();
    h= getWindowHeight();
}

void pakt06App::draw() {
    cairo::Context ctx(cairo::createWindowSurface());
    //ctx.setAntiAlias(1);
    
    ctx.setSourceRgb(0, 0, 0);
    ctx.paint();

    ctx.setLineWidth(1);
    for(size_t i= 0; i<points.size(); i++) {

        float x= (points[i].x/w)*2-1;
        float y= (points[i].y/h)*2-1;
        vec2 v= vec2(
                       (((cos(theta)*x)-(sin(theta)*y))*0.5+0.5)*w+spread,
                       (((cos(theta)*y)+(sin(theta)*x))*0.5+0.5)*h+spread
                       );
        points[i]= v;
        ctx.setSourceRgb(1, 0, 0);
        ctx.circle(v, 50);
        ctx.fill();
        ctx.setSourceRgb(1, 1, 1);
        ctx.circle(v, 50);
        ctx.stroke();
        theta= theta+speed;
    }
}

CINDER_APP(pakt06App, Renderer2d, [&]( App::Settings *settings ) {
    settings->setWindowSize( WIDTH, HEIGHT );
    settings->setResizable( false );
})