import java.text.SimpleDateFormat;
import java.util.Date;
//========================================================================================
float eccentricity[] = {0,0.205,0.007,0.017,0.094,0.049,0.057,0.046,0.011};
float aphelion[] = {0.0,69.8,108.9,152.1,249.2,816.6,1514.5,3003.6,4545.7};
float inclination[] = {0.0,7.0,3.4,0.0,1.9,1.3,2.5,0.8,1.8};
float bodyRadius[] = {0.0,0.5,0.7,0.7,0.6,1.7,1.5,3,3};
float orbitPeriod[] = {0.0,126720.0,323568.0,525888.0,989280.0,6380640.0,15475680.0,44048160.0,86112000.0};
float epoch[]={0.0,13627665.75,13630579.0,13922899.58,14241140.2,18535221.46,25301781.93,20140822.57,74731252.68};
String alert = "Solar System Simulator by LGR";
String strCurrentTime = "";
String f1= "Press 'f'/'l'key To increase / decrease the speed of the revolution.";
String f2= "Press 'UP','DOWN','LEFT','RIGHT'key To adjust the camera angle.";
String f3= "Click on the mouse to turn off or turn on the Orbits.";
String f4= "Rotate the wheel of the mouse to zoom in or out.";
String camxy = "x/y of cam : ";
String introduce1 ="When simulating in real time, the speed of the simulations ";
String introduce2 ="was so slow that I tried to accelerate the time of the simulations.";
float camx = 0, camy = 0, camz = 0, scale = 1.0;
long currentTime = 0,startTime;
int BColorR[] = {255,0,255,43,255,209,255,41,41};
int BColorG[] = {255,123,0,255,177,122,86,100,100};
int BColorB[] = {255,255,0,0,68,0,210,255,255};
int center = 0,timeRate = 0,fastForward = 0,zoom = 1;
//========================================================================================
void setup() {
size(832,624,P3D);
stroke(255);
camx=1.250;
camy=-2.850;
}
//========================================================================================
void draw() {
background(0, 0, 0);
timeChange();
showLetter();
translate(width/2, height/2, 0);
scale(scale);
rotateX(camx);
rotateY(camy);
rotateZ(camz);
fill(255,255,255);
sphere(15);
for(int planeti=1;planeti<9;planeti++) {
pushMatrix();
rotateY(radians(inclination[planeti]));
if(zoom==1){
Orbit(planeti);
}
Planet(planeti);
popMatrix();
}
}
//========================================================================================
void Planet(int j) {
float timeDiff = currentTime - epoch[j];
if(timeDiff<0) timeDiff-=orbitPeriod[j];
float i = ((2*PI)/orbitPeriod[j])*timeDiff;
float a = aphelion[j];
float e = eccentricity[j];
float r = (a*(1-(e*e)))/(1-(e*cos(i)));
float x = r*cos(i);
float y = r*sin(i);
pushMatrix();
translate(x, y, 0);
noStroke();
fill(BColorR[j],BColorG[j],BColorB[j]);
sphere(bodyRadius[j]*4);
stroke(255);
popMatrix();
}
//========================================================================================
void Orbit(int k) {
float circumference = 2*PI;
float a = aphelion[k];
float e = eccentricity[k];
float prevx = -1;
float prevy = -1;
for(float theta=0.0;theta<circumference;theta+=0.01) {
float r = (a*(1-(e*e)))/(1-(e*cos(theta)));
float x = r*cos(theta);
float y = r*sin(theta);
if(prevx == -1 && prevy == -1) {
prevx = x;
prevy = y;
} else {
line(prevx,prevy,x,y);
prevx = x;
prevy = y;
}
}
}
//========================================================================================
void showLetter() {
textSize(20);
fill(255,255,255);
text(strCurrentTime, width/2-100, 20);
text(camxy,20,510);
text(camx,150,510);
text(camy,220,510);
text(alert,20,530);
text(f1,20,550);
text(f2,20,570);
text(f3,20,590);
text(f4,20,610);
textSize(15);
fill(255,255,255);
text(introduce1, width/2-200, 50);
text(introduce2, width/2-200, 63);
}
//========================================================================================
void timeChange() {
println("time : "+timeRate);
if(timeRate==0) {
if(fastForward==0) {
Date d = new Date();
long x = d.getTime()/1000;
currentTime = x/60;
fastForward = 1;
timeRate = 1;
}
}
else if(timeRate>0) {
currentTime+=pow(2,timeRate);
}
long oriCurrentTime = currentTime * 60 * 1000;
println(oriCurrentTime);
SimpleDateFormat formatter = new SimpleDateFormat("yyyy.MM.dd HH:mm:ss");
Date d2 = new Date(oriCurrentTime);
String dTime = formatter.format(d2);
strCurrentTime = dTime;
println(strCurrentTime);
}
//========================================================================================
void mouseWheel(MouseEvent event) {
float e = event.getCount();
if (e<0) scale-=0.025;
else scale+=0.025;
}
//========================================================================================
void mouseClicked() {
if(zoom==1){
zoom = 0;
}
else{
zoom = 1;
}
}
//========================================================================================
void keyPressed() {
if (key == 'F' || key == 'f') {
if(timeRate<15){
timeRate++;
}
}
else if (key == 'l' || key == 'L') {
if(timeRate>1) {
timeRate--;
}
}
else if (key == CODED) {
if (keyCode == UP){
camx+=0.05;
}
else if (keyCode == DOWN){
camx-=0.05;
}
else if (keyCode == LEFT){
camy-=0.05;
}
else if (keyCode == RIGHT){
camy+=0.05;
}
}
}
//========================================================================================
This is the code for the solar system simulation. 
I want to apply the Hohmann transfer orbit to this simulation. 
(I’d like to get a destination input,
and then visualize the Hohmann transfer orbit from Earth to destination.)
But I can’t get the hang of it. 
Can you help me?
(Sites that show my goals : https://transfercalculator.com/calculator/index.html
