I'm looking to multiply an image when it touches another image
thank you
ronald wrote ...
2021/5/31
VARIOUS
I am thinking
I'm wondering
It is the actor that it is necessary to multiply and not the image of the actor?
That is something you must be careful with. How long will the actor be touching the "image" (of the other actor? is what Gbasire was getting at -- I think) ?
import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
/**
* Write a description of class Ball05 here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class Ball05 extends Actor
{
private int SIZE = 400;
private int a = SIZE/2;
private int b = a;
private int diameter = 4 * SIZE / 5;
private int n = 12;
public void act()
{
addBall05();
}
public void addBall05()
{
GreenfootImage img = new GreenfootImage(SIZE, SIZE);
img.setColor(Color.BLACK);
int m = Math.min(a, b);
diameter = 4 * m / 5;
int r2 = Math.abs(m - diameter) / 2;
img.drawOval(a - diameter, b - diameter, 2 * diameter, 2 * diameter);
img.setColor(Color.BLUE);
for (int i = 0; i < n; i++)
{
double angle = 2 * Math.PI * i / n;
int x = (int) Math.round(a + diameter * Math.cos(angle));
int y = (int) Math.round(b + diameter * Math.sin(angle));
img.fillOval(x - r2, y - r2, 2 * r2, 2 * r2);
}
setImage(img);
}
}
import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
/**
* Write a description of class Ball04 here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class Ball04 extends Actor
{
private int size = 400;
private int a = size/2;
private int b = a;
private int r = 4 * size / 5;
private int n = 12;
public void act()
{
drawImg();
}
public void drawImg()
{
GreenfootImage img = new GreenfootImage(size, size);
img.setColor(Color.BLACK);
int m = Math.min(a, b);
r = 4 * m / 5;
int r2 = Math.abs(m - r) / 2;
img.drawOval(a - r, b - r, 2 * r, 2 * r);
//img.setColor(Color.BLUE);
for (int i = 0; i < n; i++)
{
double t = 2 * Math.PI * i / n;
int x = (int) Math.round(a + r * Math.cos(t));
int y = (int) Math.round(b + r * Math.sin(t));
getWorld().addObject(new Ball04(), x+100, y+100);
//img.fillOval(x - r2, y - r2, 2 * r2, 2 * r2);
}
setImage(img);
}
}
The problem stems from line 38. Almost never should you add a new instance of a class into the world from the class of that instance.
If I understood correctly
I do not add a class instance in the world
If I have already added an object with Getworld in the actor
and even
No Getworld in the actor if I have already added the object in the world
I can not have both
ronald wrote...
If I understood correctly
I do not add a class instance in the world
If I have already added an object with Getworld in the actor
and even
No Getworld in the actor if I have already added the object in the world
I can not have bothsorry
I understand as I can
After the Greenfoot API, add the actor object, int x, int y
I do not understand anything anymore
The API gives you the method formats and descriptions. The non-static methods given can only be executed on an instance of that class's type (an instance specifically of that class or of any of its subclasses.
The World instance method shown as:
addObject(Actor object, int x, int y)
gives a usage of
someWorldInstance.addObject(someActorInstance, someIntValue, anotherIntValue);
In a World subclass named MyWorld, possible usages are:
The world should have full control of what happens in general. That is, initial set up and major transition points are to be coded in your World subclass. Code in Actor subclasses are for initializing actors and giving them their specific states (fields) and behaviors (methods).
// in constructor
public MyWorld()
{
super(600, 400, 1);
addObject(new Ball(), 50, 50); // "this." is implicitly understood
}
/* ********************** */
// in a method called by constructor
public MyWorld()
{
super(600, 400, 1);
prepare(); // "this." is implicitly understood
}
private void prepare()
{
Ball ball = new Ball();
addObject(ball, 0, 0); // "this." is implicitly understood
ball.setLocation(50, 50);
}
/* *********************** */
// in act method
if (this.getObjects(Ball.class).isEmpty()) this.addObject(new Ball(), 50, 50);okay
I add getObject in the ball01 actor and creates a new class ball03
it works but shows that a ball instead of 12 balls on the circle
In my opinion, I have to review the calculation formula
ronald wrote...
okay
I add getObject in the ball01 actor and creates a new class ball03
it works but shows that a ball instead of 12 balls on the circle
In my opinion, I have to review the calculation formulaimport greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
/**
* Write a description of class Ball04 here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class Ball04 extends Actor
{
private static final int SIZE = 400;
private int a = SIZE/2;
private int b = a;
private int r = 4 * SIZE / 5;
private int n = 12;
public void act()
{
paintComponent();
}
public void paintComponent()
{
GreenfootImage img = new GreenfootImage(SIZE, SIZE);
img.setColor(Color.BLACK);
int m = Math.min(a, b);
r = 4 * m / 5;
int r2 = Math.abs(m - r) / 2;
img.drawOval(a - r, b - r, 2 * r, 2 * r);
//img.setColor(Color.BLUE);
for (int i = 0; i < n; i++)
{
double t = 2 * Math.PI * i / n;
int x = (int) Math.round(a + r * Math.cos(t));
int y = (int) Math.round(b + r * Math.sin(t));
if(getWorld().getObjects(Ball06.class).isEmpty())
{
getWorld().addObject(new Ball06(), x+100, y+100);
}
//img.fillOval(x - r2, y - r2, 2 * r2, 2 * r2);
}
setImage(img);
}
}
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