I have a program that bounces an arbitrary number of balls around a predefined window. It relies on a Swing Timer to update the balls according to a delay set by the user. My problem is this: the balls lag much more than they should under modest circumstances. The weird thing is that the balls move smoothly if there is another action being performed (e.g. mouse click or mouse moving around the screen). Does anyone know what would cause this?
The weird thing is that the balls move smoothly if there is another action being performed (e.g. mouse click or mouse moving around the screen).
Based on that statement, I would guess that your problem is not properly calling repaint() on JPanel or other java.awt.Component subclass which is displaying the balls. You need to call Component.repaint() whenever your code changes the position of the balls.
Not sure if this might help: have you considered double buffering? (that is doing all expensive paint operations in an 'off-image' and copying that image into the visible area when done).
Related
I've been using a JPanel and overriding paintComponent() in order to perform my drawing in Swing games. I'm now trying to add an inventory, which will contain different items the player can drag around and move to different slots in his "backpack" on the screen. Should Swing games only draw on a single JPanel or other component (example: draw images of item at mouse location) or can you add JButtons whose icons are pictures of the items?
Should the game only have the one drawing component, or can you include more?
Principally, you can have any number of components that you want to have. Swing – as any other sufficently elaborate library such as SWT for Java or Qt and WxWidgets for C++ – is intelligent enough to draw to the screen only what actually really is necessary.
As long as you do not run into performance issues, there is no problem with that. If this actually happens, you might first want to look at your own paintComponent implementation as this is the most probable location where you lose efficiency.
I am currently making a path-laying Tile game in Java where I am using a JLayeredPane with multiple layers. The game runs fine, but everytime the repaint method is called, the entire pane flickers.
Right now I have the game running on a timer where every tick automatically moves the character one tile at a time along the path in which I have laid out. Naturally, I would need to update the screen in order to reflect the changes to the user, but the problem is that the repaint method forces a redraw on all layers of the LayeredPane. Every tick would cause a flicker on the map area of the screen. While it is bearable, I would just like to get rid of it so it looks nicer.
I have researched on the use of double buffering and have even set the option to double buffer the pane to true as well (e.g. pane.setDoubleBuffered(true)), but have had no luck with various implementations. Is there a way to just draw the entire pane with all layers for every tick in an outside buffer, then copy it in one go over to the main screen?
Thank you
I am making a game in Java. Basically, I have two different "planes" of updating that I need to take care of the. The base layer is the actual game painting itself. It is simply a JPanel that covers the entire JFrame, and is drawn to using its Graphics object.
I use a fixed timestep to take care of these first graphical updates. I have overwritten the paintComponent() method to do absolutely nothing, as I have written a custom render(float interpolation) method that takes care of that, as to prevent unwanted updates.
However, this panel can take no input beyond primitive mouse clicks and keyboard input. I need the ability to create various menus, text boxes, etc, that are also on the screen. Like various abilities, or even the "Menu" button that usually appears in the upper left corner of most games.
To take care of that input, such as creating buttons, I have a second JPanel that has setOpaque(false) applied to it. Then I create various Swing components that I might need, such as a JButton.
To contain the two JPanels, I use a JLayeredPane, and set their layers appropriately, as seen below. This way the input layer should always be on top of the actual game layer.
The code below shows how I create and add the Swing components to each other. addLoginDialog() is a method that adds a Swing component for the login. It has been tested and works properly, and isn't the problem.
private void initComponents()
{
//This code is inside of the JFrame
wholePane = new JLayeredPane();
add(wholePane);
guiPanel = new GUIPanel();
guiPanel.setOpaque(false);
gamePanel = new RPGPanel();
gamePanel.setOpaque(false);
wholePane.add(gamePanel, JLayeredPane.DEFAULT_LAYER);
wholePane.add(guiPanel, JLayeredPane.POPUP_LAYER);
guiPanel.addLoginDialog();
}
So when I run the code, I get horrible flickering. This is the code that is run from my fixed timestep ~60 times per second.
public void handleRepaint()
{
//I don't use repaint() for the game drawing so I can be sure that fps is controlled.
Graphics g = gamePanel.getGraphics();
gamePanel.render(g);
g.dispose();
wholePane.repaint();
}
The problem is, I think, that the two different systems of updating the screen are clashing. The standard paintComponent() system is great for more static screens, but when I need to update consistently and keep track of the fps, I can't have updates going off randomly.
However, for the input layer, I only want to update as Swing normally does. When the mouse moves over a button, when I component is moved or is resized, etc.
Also, note the way the screen flickers: The Background image goes blank and then comes back again repeatedly. The input panel is always there, but is actually painted behind the game drawing, which shouldn't happen, because it is put in the default layer. The reason I know it isn't completely disappearing is because the game painting is partially transparent, so I can see underneath it, and the buttons I added are still there.
My main question is, how can I stop the flickering? Why is the game drawing being drawn on top of the input components when the game drawing is being done on the Panel that is in a lower layer in the JLayeredPane? And I supposed most importantly, what is causing the flickering? Thank you for any help.
Why is the game drawing being drawn on top of the input components
when the game drawing is being done on the Panel that is in a lower
layer in the JLayeredPane?
Mostly because you've circumvented how Swing works.
Let's start with the fact that the Graphics context is a shared resource (typically there is a single Graphics context per native peer), that is, every component gets the same context, this means, when you use your own painting routine, you are basically painting over every thing else.
The RepaintManager is responsible for making decisions about what and when something should be painted. So what you now have is two artist fighting over the same canvas, wanting to paint on it simultaneously, which is just making a mess.
Add into the fray that Swing's painting process is not thread safe and you end up with a complete mess.
If you absolutely must have control, then you need to remove Swing's painting engine from the equation.
Start by taking a look at Passive vs. Active Rendering
ps- There is also hard ware acceleration benefits to using a BufferStrategy
I'd like some advice regarding structure of a game I'm working on. Specifically where to place painting methods.
Currently there is a applet wrapper class for a Jpanel which runs the game loop.
The game itself is meant to simulate a very large area. objects will have x&y values which themselves will part of a larger x&y grid.
i.e. object1 position is 150000x30000 in grid block 1,5.
objects will need to be able to move into neighbouring grids, however I'd rather not run each grid block until needed as 99% of them will be empty.
Currently the UI is a Jpanel with a few buttons + listeners, a large drawing pane is needed to display the objects.
my question is:
what class should this internal drawing pane be based on? I'd like to have control to zoom and pan around the grid. it only needs to draw what is visible, but object movements will continue in the game loop.
what painting strategy would be applicable for simple (icons really when zoomed out) moving around vast areas, I'm guessing relying on the EDT to repaint isn't going to be good enough?
I'm not really after specific code, I want to learn myself how to do this, I just need pointing in the right direction, as most things I read don't seam to quite cover what I'm after, or don't make use of JRE6+ features.
Many Thanks
Rather than paint each grid cell in your drawing pane, why don't you have each object repaint itself onto the grid?
I am writing a game in Java, and need to have mouse interaction. I was going to use MouseAdapter, but I've looked into it some, and it does not seem to have any means of determining the location of the mouse pointer without a click or action being done... What would be the recommended way of doing this?
A couple questions:
Would the mouse "location" refer to the location of the mouse in relation to the bounds of the monitor, the bounds of the game, or would it be represented as movements relative to a previous location?
How would one disable the mouse pointer in a windowed application? (ie. A first person shooter where the mouse movements rotates the players view rather than move a pointer) Is this possible?
Look at the MouseMotionListener. This will allow you to track mouse movements. It will give you the location of the mouse within the component that it is attached to. But if you look at SwingUtilities class there are some convenience methods to convert points to the screen or other components or the monitor.
For the cursor, you have the option to set your own bitmap for the cursor, you can look here. Or for a more recent SO answer, you can look here. So you could hide the cursor, or set it to an empty bitmap, and then intercept the mouse movements and events to control your view.
A tutorial on mouse events is at:
http://java.sun.com/docs/books/tutorial/uiswing/events/mouselistener.html
If you look here:
http://java.sun.com/javase/7/docs/api/java/awt/event/MouseEvent.html
you can get the absolute location, on the screen, or coordinates relative to the component.
If there is a movement to change direction then you will need to remove the mouse listener, or you can just have some logic where the event handler will just exit, doing nothing. I think this would be better, otherwise you have to keep track of when you add and remove the listeners.