【OF】Ring

void ofApp::draw(){

    ofPath circle;
    int rad = 100;
    int rad2 = 200;
    ofPoint center(ofGetWindowWidth()/2,ofGetWindowHeight()/2);

    ofEnableAlphaBlending();

    circle.setFillColor(ofColor(255,0,0,127));
    circle.arc(center, rad, rad, 0, 360);
    
    // close internal circle
    circle.close();

    // outside circle
    circle.arc(center, rad2, rad2, 0, 360);
    circle.setCircleResolution(100);
    
    circle.draw();
    
    ofDisableAlphaBlending();

}