openframeworks sketch

void P_1_1_2_01App::setup()
{
    savePDF = false;
    segmentCount = 360;
    radius = 300;
    ofSetWindowShape(800, 800);
}

void P_1_1_2_01App::draw()
{
    if (savePDF) {
        ofBeginSaveScreenAsPDF("screenshot-" + ofGetTimestampString() + ".pdf", false);
    }

    int width = ofGetWindowWidth();
    int height = ofGetWindowHeight();

    float angleStep = 360 / segmentCount;

    ofMesh mesh;
    mesh.setMode(OF_PRIMITIVE_TRIANGLE_FAN);
    mesh.addVertex(ofVec3f(width / 2, height / 2));

    for (float angle = 0; angle <= 360; angle += angleStep) {
        float vx = width/2 + cos(ofDegToRad(angle)) * radius;
        float vy = height/2 + sin(ofDegToRad(angle)) * radius;
        mesh.addVertex(ofVec3f(vx, vy));

        float a = ofMap(angle, 0, 360, 0, 255);
        float mx = ofMap(mouseX, 0, width, 0, 255);
        float my = ofMap(mouseY, 0, height, 0, 255);
        mesh.addColor(ofColor::fromHsb(a, mx, my));
    }
    //    mesh.draw();
    mesh.drawWireframe();

    if (savePDF) {
        savePDF = false;
        ofEndSaveScreenAsPDF();
    }
}

processing sketch

boolean savePDF = false;

int segmentCount = 360;
int radius = 300;


void setup(){
  size(800, 800);
}

void draw(){
  if (savePDF) beginRecord(PDF, timestamp()+".pdf");

  noStroke();
  colorMode(HSB, 360, width, height);
  background(360);

  float angleStep = 360/segmentCount;

  beginShape(TRIANGLE_FAN);
  vertex(width/2, height/2);
  for (float angle=0; angle<=360; angle+=angleStep){
    float vx = width/2 + cos(radians(angle))*radius;
    float vy = height/2 + sin(radians(angle))*radius;
    vertex(vx, vy);
    fill(angle, mouseX, mouseY);
  }
  endShape();

  if (savePDF) {
    savePDF = false;
    endRecord();
  }
}