openFrameworks custom arc drawing. used to draw arcs similar to flight patterns, using my own data.

arcs.cpp

//
//  mapArc.cpp
//
//  Created by Aaron Sherwood on 3/29/13.
//  Copyright 2013. All rights reserved.
//

#include <iostream>
#include "mapArc.h"

//--------------------------------------------------------------
mapArc::mapArc(){
    go = false;
    up = -1.0472;
    down = 1.0472;
    minSpeed=2; //set lower for faster
    maxSpeed=20; //set higher for slower
}

//--------------------------------------------------------------
void mapArc::init(ofVec3f s, ofVec3f f){
    start = s;
    finish = f;
    ad = finish-start;
    angle = atan2(ad.y, ad.x);
    if (angle<=0) angle += 2*PI;
    arcDirection;
    if (start.y<=finish.y&&start.x>=finish.x) {
        arcDirection=down;
    } else if (start.y<=finish.y&&start.x<=finish.x){
        arcDirection=up;
    } else if (start.y>=finish.y&&start.x<=finish.x){
        arcDirection=down;
    } else if (start.y>=finish.y&&start.x>=finish.x){
        arcDirection=up;
    }
    anchor.x=ad.length()*cos(angle+arcDirection)+start.x;
    anchor.y=ad.length()*sin(angle+arcDirection)+start.y;
    ofVec3f originVec=start-anchor;
    originAngle=atan2(originVec.y,originVec.x);
    if (originAngle<0) originAngle += 2*PI;
    startAngle=originAngle;
    go=true;
}

//--------------------------------------------------------------
void mapArc::incrementAngle() {
    archCoords.x=ad.length()*cos(originAngle)+anchor.x;
    archCoords.y=ad.length()*sin(originAngle)+anchor.y;
    
    if (go) {
        arc.addVertex(archCoords.x, archCoords.y);
        
    } 
    
    if (arcDirection==down){
        if (originAngle>=startAngle+down-.1) {
            go=false;
        }
        float dest=ofClamp((startAngle+down)-originAngle,0,startAngle);
        originAngle+=dest/ofMap((startAngle+down), 0,7, minSpeed, maxSpeed,true);
    }
    
    if (arcDirection==up){
        if (originAngle<=startAngle+up+.1) {
            go=false;
        }
        float dest=ofClamp(originAngle-(startAngle+up),0,startAngle);
        originAngle-=dest/ofMap(startAngle+up, 0., 7, minSpeed, maxSpeed,true);
    }
}