openFrameworks 3D vector animation

ofApp.cpp

#include "ofApp.h"

void ofApp::setup() {
}

void ofApp::update() {
    for (int i = 0; i < location.size(); i++) {
        location[i] += velocity[i];
        if (location[i].x < 0 || location[i].x > ofGetWidth()) {
            velocity[i].x *= -1;
        }
        if (location[i].y < 0 || location[i].y > ofGetHeight()) {
            velocity[i].y *= -1;
        }
        if (location[i].z < -500 || location[i].z > 500) {
            velocity[i].z *= -1;
        }
    }
}

void ofApp::draw() {
    for (int i = 0; i < location.size(); i++) {
        ofDrawCircle(location[i], 5);
    }
    ofDrawBitmapStringHighlight(
        "Num = " + ofToString(location.size()), 20, 20);
    ofDrawBitmapStringHighlight(
        "FPS = " + ofToString(ofGetFrameRate()), 20, 40);
}

void ofApp::mouseDragged(int x, int y, int button) {
    glm::vec3 loc = glm::vec3(x, y, 0);
    location.push_back(loc);
    glm::vec3 vel = glm::vec3(ofRandom(-2, 2), ofRandom(-2, 2), ofRandom(-10, 10));
    velocity.push_back(vel);
    if (location.size() > NUM) {
        location.erase(location.begin());
        velocity.erase(velocity.begin());
    }
}

ofApp.h

#pragma once
#include "ofMain.h"

class ofApp : public ofBaseApp {

public:
    void setup();
    void update();
    void draw();
    void mouseDragged(int x, int y, int button);

    static const int NUM = 1000;
    vector<glm::vec3> location;
    vector<glm::vec3> velocity;
};