hello,
sorry, looking again at
http://upload.wikimedia.org/wikipedia/en/thumb/6/69/Kepler-second-law.gif/220px-Kepler-second-law.gif
I think
I was on the wrong track
- Your problem is not that the (visual) speed changes too much (that's what I thought and where lerp could help imho)
- but your problem is that the acceleration and deaccleration during one round around the sun is missing, right?
for #2 you have the var krok. You could vary that slightly to get the effect. So when it goes towards the sun, it increases slightly, when it leaves the sun it decreases a bit. A similar event can be seen in the code below.
for #2 you'll find in the examples in the IDE
topics / simulate / GravitationalAttraction3D by Daniel Shiffman.
Greetings, Chrisir
// from
http://processing.org/learning/topics/arraylistclass.html
// with fading!!!!!!!!!!!
ArrayList balls;
int ballWidth = 48;
// =====================================================================
void setup() {
size(500, 500);
// size(screen.width, screen.height);
smooth();
noStroke();
// Create an empty ArrayList
balls = new ArrayList();
// Start by adding one element
balls.add(new Ball(width/2, 0, ballWidth, color (random(0, 255), random(0, 255), random(0, 255))));
}
void draw() {
// delete
background(111);
// maybe add new Ball
if (random (0, 1000)>940) {
// A new ball object is added to the ArrayList (by default to the end)
balls.add(new Ball(random(width), random(-400, height), ballWidth, color (random(0, 255), random(0, 255), random(0, 255))));
}
// With an array, we say balls.length, with an ArrayList, we say balls.size()
// The length of an ArrayList is dynamic
// Notice how we are looping through the ArrayList backwards
// This is because we are deleting elements from the list
for (int i = balls.size()-1; i >= 0; i--) {
// An ArrayList doesn't know what it is storing so we have to cast the object coming out
Ball ball = (Ball) balls.get(i);
ball.move();
ball.diminish();
ball.display();
// maybe kill it
if (ball.finished()) {
// Items can be deleted with remove()
balls.remove(i);
} // if
if (ball.finishedByOpacity () ) {
// Items can be deleted with remove()
balls.remove(i);
} // if
}
}
// =====================================================================
void mousePressed() {
// A new ball object is added to the ArrayList (by default to the end)
balls.add(new Ball(mouseX, mouseY, ballWidth,
color (random(0, 255), random(0, 255), random(0, 255))));
}
// =====================================================================
// Simple bouncing ball class
class Ball {
float x;
float y;
color myColor;
float speed;
float gravity;
float opacity;
float w;
float life = 255;
Ball(float tempX, float tempY, float tempW, color tempmyColor1) {
x = tempX;
y = tempY;
w = tempW;
myColor=tempmyColor1;
speed = 0;
gravity = 0.1;
opacity=255; // opacity
}
void move() {
// Add gravity to speed
speed = speed + gravity;
// Add speed to y location
y = y + speed;
// If square reaches the bottom
// Reverse speed
if (y >= height-19) {
// Dampening
speed = speed * -0.8;
y = height-19;
}
}
boolean finished() {
// Balls fade out
// life--;
if (life < 0) {
return true;
}
else {
return false;
}
}
boolean finishedByOpacity () {
if (opacity<=0) {
return true;
}
else {
return false;
}
}// func
void display() {
// Display the circle
//fill(0, life);
fill(myColor, opacity);
//stroke(0,life);
ellipse(x, y, w, w);
}
void diminish() {
opacity = opacity-0.5;
} // func
} // class
// =====================================================================
