How can i code the ball to bounce off the worlds edge when it hits either the top,bottom right or left edge?
chamuzi3 wrote ...
2014/10/4
Bouncing opposite direction when the ball hits the worlds edge.
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That depends on what movement code you already have. Show your code. Use 'code' link below the 'Post a reply' input box to insert any code within your posts.
when the ball hits the right or left edge, it gets stack.please help
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | public void act() { move(5); checkWalls(); } public void checkWalls(){ if(atWorldEdge()){ setRotation(getRotation()*-1); } } public boolean atWorldEdge() { if(getX() < 10 || getX() > getWorld().getWidth() - 10) return true; if(getY() < 10 || getY() > getWorld().getHeight() - 10) return true; else return false; } |
So, your movement direction is determined by the rotation of the actor. Negating the rotation, however does not reverse the movement direction consistently. That is, at 90 or 270 degrees, it will work perfectly; but the further from those values the rotation of the actor becomes, the worse it will work. At zero or 180 degrees rotation, there will be no apparent change when the rotation is negated. This means you will have to deal with the horizontal and vertical movements separately; and, negate only the movement along only one of the two directions when an edge is encountered. This can be accomplished by using the rotation, and the code you have will work for top and bottom edges. For a side edge bounce another 180 degrees will have to be added after negating the rotation.
I also have another question, i have two tank(actors) 1 and 2 but when am controlling them, dont want them to go through each other as i want them to collide ed when i hit a wall i stop but i can still move away from it so i want to do the same thing for both tanks so that they can go through each other. How can i do this?? :)
And also have another problem. Two tanks(Tank and Tank2). Tank one shoots Bullet and Tank2 shoots Bullet2. i will send the code. When i put both the tanks in the game, one can shoot but one cant.Let me send you the code.
this is for Tank one shooting Bullet and for Tank 2
1 2 3 4 5 6 7 8 9 10 | private void shoot() { if("f".equals(Greenfoot.getKey())) { Bullet bullet=new Bullet(); getWorld().addObject(bullet,getX(), getY()); bullet.setRotation(getRotation()); bullet.move(75); } } |
1 2 3 4 5 6 7 8 9 10 | private void shoot(){ if("p".equals(Greenfoot.getKey())) { Bullet2 bullet2=new Bullet2(); getWorld().addObject(bullet2,getX(), getY()); bullet2.setRotation(getRotation()); bullet2.move(75);} |
You cannot use 'getKey' more than once per act cycle. The second time it is executed will return 'null' if you are always checking for a key. You either need to find a central location to get the key, saving it in a local variable, so you can check for both possible keys or use 'isKeyDown' with boolean fields to track the state of each key being down or not.
The first way may have to be coded in your world class act method using something like this:
You will probably have to change the access of your 'shoot' methods to 'public' and add conditions that the tanks are in the world.
The other way would involve adding instance Boolean fields to the classes of the tanks and perform a pair of double-conditions for trigger and trigger release. Something like this:
1 2 3 | String key = Greenfoot.getKey();if ("f".equals(key)) // code to have Tank object shoot a Bulletif ("p".equals(key)) // code to have Tank2 object shoot a Bullet2 |
1 2 3 4 5 6 7 8 9 | // instance fieldprivate boolean shotKeyDown;// in act methodif (!shotKeyDown && Greenfoot.isKeyDown("f")){ shoot(); shotKeyDown = true;}if (shotKeyDown && !Greenfoot.isKeyDown("f")) shotKeyDown = false; |
also have another question, i have two tank(actors) 1 and 2 but when am controlling them, dont want them to go through each other as i want them to collide ed when i hit a wall i stop but i can still move away from it so i want to do the same thing for both tanks so that they can go through each other. How can i do this?? :) code if you can. Thanks for your help btw
am new to greenfoot and coding.
Is there a way of me sending you what i have so far in my game so that you can see for your self whats happening and where the problem is??
danpost wrote...
The first way may have to be coded in your world class act method using something like this:
1 2 3 | String key = Greenfoot.getKey();if ("f".equals(key)) // code to have Tank object shoot a Bulletif ("p".equals(key)) // code to have Tank2 object shoot a Bullet2 |
1 2 3 4 5 6 7 8 9 | // instance fieldprivate boolean shotKeyDown;// in act methodif (!shotKeyDown && Greenfoot.isKeyDown("f")){ shoot(); shotKeyDown = true;}if (shotKeyDown && !Greenfoot.isKeyDown("f")) shotKeyDown = false; |
Is there a way of me sending you what i have so far in my game so that you can see for your self whats happening and where the problem is??
If you are as new as you say, maybe you should review the tutorial trails provided by oracle (java). You can go here. Study the 'Trails Covering the Basics' (second section on left). Greenfoot has tutorials on how to use the IDE it provides which should be checked out after the java trails. You should then have a better understanding of the classes greenfoot supplies and you can afterwards apply what you have learned to the classes you create within greenfoot.
You can share your scenario on this site. Click on the 'Share' button on the top-right of your scenario frame and supply the information requested (you should start at the 'Publish' tab in the pop-up dialog box). Make sure you check to 'Publish source code' checkbox so others can download it and look at the code.
chamuzi3 wrote...
Is there a way of me sending you what i have so far in my game so that you can see for your self whats happening and where the problem is??There are more replies on the next page.
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