3D Baton Circles move around a Sun - processing

Question

How do I use translate and rotate to position spheres and lines on the canvas and also rotate the entire scene with Java Processing?
I need to be able to do this so that I can:
Create a class for a 3D baton which contains two equal size spheres and a line connecting the centers of the two spheres. The Baton class must have the following field variables:
float x, y, z; // the x, y, z coordinates of the center of one baton sphere
// the other baton sphere should be (-x, -y, -z)
float angle; // rotation angle
float speed; //rotational speed
float radius; //radius of the baton sphere
In the main tab of the sketch I need to create a scene that contains the following:
A yellow sphere with radius 50 at the center of the window. The yellow sphere doesn’t move.
6 batons rotating about the y axis passing through the yellow sphere.
Each baton rotates at a random speed between 0.01 and 0.04.
All batons have different distances from the center of the yellow sphere.
The radius of each baton sphere is a random number between 15 and 30.
3D Batons Picture
This is my code:
Baton[] batons;
void setup() {
size(600, 600);
batons = new Baton[4];
for(int i = 0; i < batons.length; i++)
batons[i] = new Baton(100, 100, 100, 45, 2, 25, 2);
}
void draw() {
background(255);
stroke(0);
translate(width/2, height/2);
fill(255, 200, 50);
sphere(50);
for(int i = 0; i < batons.length; i++) {
batons[i].update();
batons[i].display();
}
}
class Baton {
float x;
float y;
float z;
float angle;
float speed;
float radius;
float theta;
Baton(float x, float y, float z, float angle, float speed, float radius, float theta) {
this.x = x;
this.y = y;
this.z = y;
this.angle = angle;
this.speed = speed;
this.radius = radius;
theta = 0;
}
void update() {
theta = theta + speed;
}
void display() {
pushMatrix();
rotate(theta);
translate(radius/2, 0);
fill(51, 51, 51);
noStroke();
sphere(radius);
popMatrix();
line(x, y, -x, -y);
pushMatrix();
rotate(theta);
translate(radius/2, 0);
fill(51, 51, 51);
noStroke();
sphere(radius);
popMatrix();
}
}
The Baton has to go through the Sun that is in the middle. This means that the two circles and the line that connects it has to rotate around the Sun. To explain easier the line will go through the Sun and rotate with the two Circles. See the picture link above.

Answer 1

The main thing that makes your code render differently than the image you have attached is that the Baton objects are placed at the center of the canvas and end up being hidden by the sphere at the center.
Here I have moved the Baton spheres out away from the center and have slowed down the frameRate and speed so that it is easier to see how they are moving.
Baton[] batons;
void setup() {
size(600, 600, P3D);
batons = new Baton[4];
frameRate(1); // slowed down the frame rate to 1 frame per second
for(int i = 0; i < batons.length; i++){
// changed speed from 2 to 0.1 so that the batons move in smaller increments
batons[i] = new Baton(100, 100, 100, 45, 0.1, 25, 2);
}
}
void draw() {
background(255);
stroke(0);
translate(width/2, height/2);
fill(255, 200, 50);
sphere(50);
for(int i = 0; i < batons.length; i++) {
batons[i].update();
batons[i].display();
}
}
class Baton {
float x;
float y;
float z;
float angle;
float speed;
float radius;
float theta;
Baton(float x, float y, float z, float angle, float speed, float radius, float theta) {
this.x = x;
this.y = y;
this.z = y;
this.angle = angle;
this.speed = speed;
this.radius = radius;
theta = 0;
}
void update() {
theta = theta + speed;
}
void display() {
pushMatrix();
// since we want the entire configuration to rotate we will rotate the entire canvas
rotate(theta);
// for a more interesting rotation we could do this instead:
// rotateX(theta);
// rotateY(theta);
// rotateZ(theta);
float distanceBetweenBatonSpheres = radius + 300;
translate(distanceBetweenBatonSpheres/2, 0);
fill(0, 200, 200);
sphere(radius);
// now we undo the previous translate and also move back out to the other side of the central sphere
translate(distanceBetweenBatonSpheres/-1.0, 0);
sphere(radius);
// and finally.. draw a line to connect the two spheres
line(0,0,distanceBetweenBatonSpheres, 0);
popMatrix();
}
}
Notice how we rotate the entire canvas so that the configuration of spheres rotates as a body along with the line that connects the baton spheres.
Also see the comments about making the sketch more interesting by rotating in the x, y and z directions.