I'm working on a simple game with libGDX and want to make the main character to be fixed in the center of the screen and the world move when I press a button. I was wondering how to do... I was thinking to add a physicsBody to the world that contains other bodies and apply impulses to it when the button is pressed, is this possible in libGDX? And if it is, can i apply other impulses or forces to the bodies contained in the world's physicsBody? I think this way would be the best for me if it is possible, because i have to work a lot with physics, but if you have other ideas tell me please
There's no need to think about applying forces to all the non-character objects, that's just going to get messy very quickly.
The simple solution is to move your camera so that it always looks at your character. So your game loop may look something like:-
Process input
Update physics, character and other entity positions.
Move camera to point at character's new position.
Render
This way, you can update your game world without having to think about the camera at all. Then, when it comes to rendering, you can position your camera and render your graphics without needing to know anything about the game physics. It keeps the physics and rendering relatively independent, and makes it much easier to change things in the future.
For example, you may later decide that you want the camera to follow your character for the most part, but then follow a baddy whilst it is their turn. This is now easy to do, you just specify the character / entity to look at in your game logic, and then position the camera to look at whatever target that is, before you render.
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I'm currently developing a 2D RPG with LWJGL, and am still in the engine stage of development. I've got a lot of the tech I want created, but one of my big problems is fixing the camera on the player. All the solutions I've seen involve moving the world and keeping the player still, which can work, but it seems apparent that this can cause some calculation issues if not closely monitored. Normally, I'd write a system where I wouldn't have to worry about it, but I refuse, because I eventually intend on adding multiplayer capability, where a moving world would be unplayable.
Is there a way to affix the camera to an object or point that can move WITHOUT using translate to move the world around? Also, I'd like to avoid Slick if possible. That would require me to rework much of my game engine as it currently stands.
Whenever you are going to project the 3d viewport onto a 2d screen you need to move everything according to the point of view of the observer (the so called camera or view).
I guess you can't escape from this. What you usually do is having a Camera object which holds position and rotation that is used to build the view matrix which is passed to the vertices of your scene through a uniform to the shaders. Passing transformation matrices to shaders is the normality so you shouldn't feel burdened by it. You can always premultiply it with the perspective matrix.
You must move the whole world to match the position of your camera just because you need to transform everything in your scene as it is seen from that point of view, otherwise how could you then project it on your screen? There is no "move the camera, keep the world still" concept.
Move the world visually, it's how every other RPG does it. Don't move the actual world's location though.
Draw everything but the ui normally, than translate it all according to the players position (i.e. glTranslate2f(-player.x,-player.y)). This is all done in the render method. On networked multiplayer, the viewport is done to that specific player (i.e. Bob's screen is translated based off Bob's position, Jane's is translated based off Jane's position). Should you instead want single-screen multiplayer, you will probably have to use mutliple framebuffers (one per player), and use them as viewports.
I would like to develop a game on Android platform, I have about a year experience with Java and also used the OpenGL library in C++. I also programmed Minesweeper and Connect Four in Java. Basically, here's the type of game I want to create:
Pressing the screen would make your character go up in the screen and releasing it will make it go down. I know there are games like this already but it doesn't matter to me, it's my current goal.
The structure of both games I programmed was quite easy, it was only a GridLayout. This wouldn't fit in any defined layout. Then, I have absolutely no idea how to test a character/environment collision. I'm also wondering what would be the easiest/fastest way to draw the "collision" environment, I assume it would be with OpenGL but from what I know, it would still take a long time and wouldn't be that easy.
I've been trying to find a tutorial about this but obviously, I've been unsuccessful.
PS: I already know the basics to make an Android app so you shouldn't need to worry about that.
think about each segment of what you're trying to achieve individually.
First off, you could probably read up on libgdx: http://code.google.com/p/libgdx/
it's a great android game engine which will do alot for the work for you.
For the player, think of it as just incrementing the players y position by a few pixels if it's pressed down, else decrement it.
For the map, you'd probably need some sort of 2d polygon based collision for the upper and lower collideable environments, libgdx has a physics library built in but i'm not sure how the support it for polygon-based collision. And finally, just create the map and make it wider than your game screen, and just move the camera along as the player moves.
I'm trying to make it so when a sprite which is attached to a physics body overlaps another sprite on the level something happens. The second sprite is NOT attached to a physics body.
More specifically when the two sprites are overlapping I want the game to constantly check to see if the distance between the centers of the sprites is less than a certain amount or not. Then if the distance is small enough something will happen.
I'm trying to use collision checking as a way of optimizing the game so it doesn't have to constantly check distances between every single object of type A and B even if they're not even close. It will only check the distance when they're close enough to be overlapping.
Now what I am wondering is how can I do this? Is there a way to check collisions between sprites as part of AndEngine? Or would it be easier to attach a physics body to the second object also and then just use physics collision detection? But then if I do that can I make it so the collision will be detected but they won't actually physically "collide"?
Yes, see CollisionDetectionExample.java. I suggest you download the whole examples package, it is very useful in the absence of any documentation for AndEngine. Please note that collision detection is not pixel perfect, so it will still detect collisions of transparent parts of the Sprites. There is a library for that, but I am afraid it is outdated.
I'm currently working on my 2D game project (Java), but so far any kind of game logic or AI has been crudely implemented. For instance, say I need to randomly position a bunch of sprites a long the top of the screen, I'd be using the Random class to do this. I'd simply use Random.nextInt( size of x axis on which to spawn ); Although this does work I'd be interested to hear how I should really be going about this kind of thing.
As a second scenario (this is why I put AI in the title, although it's not really AI), say I want to have my characters randomly blink in a life-like fashion. What I'd do here is use the Random class to calculate a % (say 20% chance) of blinking and call it every second.
Any suggestions on how I should really be going about this would be greatly appreciated.
Google for a paper titled "Steering Behaviors" by Craig Reynolds. It address just this and you'll find great ideas to start with specifically some nice ideas for giving groups of sprites the appearance of 'intelligent' movement. The key for him in his different behaviors, i.e. flocking, etc. is making properties of any given sprite dependent on those of some other sprite. You could even go so far as to say, like -- any given sprite will blink only if it's two neighbors just have blinked. Something or other along those lines.
Hope this helps!
Are you using an OOP (Object-Oriented approach)? If not, you should definitely look into it. It's really simple with java and can speed up your development time and neaten your code.
I would make a sprite class, and give them a function, say actionSpawn, or actionMove (I like to start my "action" functions with the word action so they are easily identifiable). In this function you would encapsulate the Random.nextInt function, to set the sprite's x and/or y position.
You could use the same approach to make them blink.
I need to make a text-based RPG game with java. The first part of the assignment is super simple. we just use vertical lines and underscores to make a little rectangle and then add symbols inside the rectangle as things move, act, die, etc.
I've never done this before, so I want to run my idea by you:
What do you think about doing something like angry birds but with flying moving targets? There would be a little "bird tank" at the bottom left of the screen that would shoot birds. Another question: I'm not entirely sure how I would create a gun that shoots at different angles in a text-based format. And how would it work with aiming and shooting and timing, and such?
Update:
I think I'm going to try out a tank game. But I'm confused about how to implemenent the angle of the turret.
I would put the tank in the bottom left corner, put I only have text symbols at my disposal. I don't see how its possible to let the user control the turret, and make it move up and down by small amounts (at least, not until we start using images/gui's.)
Any ideas?
First, in order to make your idea meet the criteria of an RPG, you would have to add a few components. Your gun would need to gain experience as you hit your targets, and would have to level up after enough time. It could gain better speed or accuracy. It could also earn upgrade points that you could spend on different birds to shoot. It would probably also be cool if your targets had hit points and you had to hit some of them multiple times to kill them. You could show the damage by changing the color of the text. These elements will give it more of an RPG feel so that you can meet the criteria of the assignment.
As for the mechanics of the game, you're going to have to write some sort of physics engine. It doesn't have to be very complicated, just enough to be able to calculate or modify a trajectory and determine if there was a collision. This engine would have some sort of a tick() method on it where it would advance the positions of the birds and targets and then you could call a getCollisions() method and handle each one. That's the simple way. The more complex way would involve giving the engine its own thread where it runs constantly, as fast as it can. Then, when there is a collision, it fires off an event to a listener, and you set up some sort of handler to apply the damage to the target, award points, etc.
I would recommend you model the world in finer resolution than your text console. Make the text console simply mark the birds and targets by rounding them to the nearest 80x25 console location, but internally use a much higher resolution. This will keep it looking more realistic, even in an environment with such a poor resolution.
For the controls of the game, I would recommend putting a target reticule on the screen. The user can move it around with their arrow keys to aim and press the space bar to shoot. They wouldn't hit the target because gravity should pull the bird downward, or perhaps because the bird is a special shot that splits into pieces. Regardless, they would learn how to lead their targets appropriately, and that would be the skill of the game.
It's a complicated project. Good luck!