in libgdx game
I want to touchDown and then drag somewhere and then on the release (touchUp) apply a directional force based on the distance and direction from the target body. When you touchdown the target body stays still and then on touchup the force is applied along the desired trajectory.
(very similar to Angry birds - where you get to see the trajectory in dotted lines for the target body when you hold hack the slingshot - I want to do the same)
So I guess that this might not be the hardest thing to do but given a few options Im leaning towards using a MouseJointDef but its an immediate force applied (i.e. the target moves immediately - I want it to stay still and then once the touchup event happens then apply the force)
Whats the easiest way to draw the trajectory also? Im using Box2D also.
Create a class that inherits InputAdapter class, then create an instance of it and register it to listen the touch inputs.
Gdx.input.setInputProcessor(inputAdapter);
There are 3 methods to handle the touch events touch_down, touch_dragged and touch_up that you have to override.
In touch_down, check the touching position to whether is in the birds area or not. If it is, make a boolean flag true.
In touch_dragged, check the flag above and if it was true, calculate the distance of the touch position relative to the bird shooting center and the shooting angle.
In touch_up, you can order to shoot with the calculated amounts by calling
body2shoot.applyLinearImpulse(impulse, body2shoot.getWorldCenter());
There is no need to MouseJointDef to move the body2shoot. Just set the transform of body2shoot in touching position to be dragged in each cycle of render.
For calculating the trajectory I wrote a class like this:
public class ProjectileEquation
{
public float gravity;
public Vector2 startVelocity = new Vector2();
public Vector2 startPoint = new Vector2();
public ProjectileEquation()
{ }
public float getX(float t)
{
return startVelocity.x*t + startPoint.x;
}
public float getY(float t)
{
return 0.5f*gravity*t*t + startVelocity.y*t + startPoint.y;
}
}
and for drawing it just I set the startPoint and startVelocity and then in a loop I give a t (time) incrementally and call getX(t) and getY(t).
Related
I have a camera which I control using WASD, but I'm stuck on moving it left and right. I've been looking all over the internet and it says to find a vector perpendicular to another you change the x and y round and times one of them by -1. I've tried this in the code below:
void camstrafe (String dir) {
Vector3 direction = camera.direction.nor();
Vector3 old = direction;
direction.set(-old.z, 0, old.x);
camera.translate(direction.scl(0.18f));
}
I have moving forwards working fine, and actually turning the camera round, but for some reason this doesn't work, and to be honest I'm not sure what it really does because when I press a or d (they call this function) the camera just goes crazy and starts turning round really quickly and sometimes going forwards or like a million miles sideways. Anyway, does anyone know how I could do this properly? By the way I've also tried getting the forward direction of the camera and using the .rotate() function rotating it 90 degrees right/left then translating it that way but that does the same thing. I'm thinking maybe cameras don't work the same was as other things do when translating them sideways/backwards.
To archive camera movement between 2 vectors use the camera lerp:
public class myclass {
[...]
private OrthographicCamera camera;
public Vector3 posCameraDesired;
[...]
private void processCameraMovement(){
/// make some camera movement
posCameraDesired.x+=100.0f * Gdx.graphics.getDeltaTime();
posCameraDesired.y+=100.0f * Gdx.graphics.getDeltaTime();
}
[...]
//render method
public void draw(){
[...]
processCameraMovement();
camera.position.lerp(posCameraDesired,0.1f);//vector of the camera desired position and smoothness of the movement
[...]
}
First, in your class, you must have an Animations object, lets call it Anim. In your class instanciation, you must create an OrthographicCamera object, that will be your camera instance. You have to give it a value, such as :
camera = new OrthographicCamera(Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
This camera coordonates can be set up the first time you use it, and you can do it with the method .translate() :
camera.translate(camera.viewportWidth / 2, camera.viewportHeight);
Otherwise the positio will be set at 0;0.
In your render() method, you have to use a method from the camera object called update(), like bellow :
#Override
public void render(float delta) {
anim.load();
camera.update();
....
game();
....
}
This method is always running during the game/app you develop. So every time the method runs, the camera is updated, and its position too.
Then, in your game() method, or in an other method (depending on your architecture), where you are dealing with the inputs of the user, you move the position of the camera, and modify the camera.position in it. like bellow :
public void game() {
if (Gdx.input.isKeyPressed(Input.Keys.LEFT)) { // or A
moveBack(anim); // The method to move back
camera.position.x -= 3; // if conditions are ok, move the camera back.
} else if (Gdx.input.isKeyPressed(Input.Keys.RIGHT)) { or D
moveForward(anim); // The method to move forward
camera.position.x += 3; // if conditions are ok, move the camera to the front.
}
When the user is moving, the method to move is called, and the camera position is modified. Each time the method render() is called, the camera is updated with its new position.
I'm trying to make a simple bit of code that will detect whether a model was clicked on. So far the best method I've seen is to create some sort of rectangle around the mesh and detect with Gdx.input.justTouched() to get the x,y coordinates, and then check if the rectangle contains the coordinates returned by justTouched().
I have no idea if there's a better way to do this, some kind of mesh onClick listener or something that LibGDX has in place that I'm unaware of (I've been scouring Google and the javadocs but I can't seem to find anything). I don't really need to deal with the z-axis coordinate, at least I don't think so. I only have the one PerspectiveCamera and it's not going to be moving around that much (not sure if this matters?)
Anyways, in my render() method I have:
if (Gdx.input.justTouched()) {
//this returns the correct values relative to the screen size
Vector2 pos = new Vector2(Gdx.input.getX(), Gdx.input.getY());
//I'm not sure how to get the correct rectangle to see what the
//width and height are for the model relative to the screen?
Rectangle modelBounds = new Rectangle(<<not sure what to put here>>);
if (modelBounds.contains(pos.x, pos.y) {
System.out.println("Model is being touched at: " + pos.x + ", " + pos.y);
}
}
I'm really not sure if this is the correct way to do this. I can get the position of the model with:
modelInstance.getNode("Node1").globalTransform.getTranslation(new Vector3());
but I'm not sure how to get the width and height as a rectangle relative to the screen size, if it's even possible.
I'm also unsure if this would cause massive lag, as I'm going to have about 7 nodes total that I need to detect if they're clicked on or not.
Is there a better way to do this? If not, is there a way to get the model width & height relative to the screensize (or camera, maybe)?
EDIT: Read about using Bounding Boxes, seems like what I need. Not quite sure how to implement it properly, however. I've changed my code to such:
public ModelInstance modelInstance;
public BoundingBox modelBounds;
#Override
public void create() {
...
//omitted irrelevant bits of code
modelInstance = new ModelInstance(heatExchangerModel);
modelBounds = modelInstance.calculateBoundingBox(new BoundingBox());
}
#Override
public void render() {
...
if (Gdx.input.justTouched()) {
Vector3 pos = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0);
System.out.println(pos);
if (modelBounds.contains(pos)) {
System.out.println("Touching the model");
}
}
}
I'm not really sure what the output of BoundingBox is supposed to be, or how the numbers it gives me correlates to the position in a 2d space. Hmm..
EDIT2: Think I'm getting closer.. Read about Rays and the .getPickRay method for my PerspectiveCamera. .getPickRay seems to return completely unusable numbers though, like really tiny numbers. I think I need to do something like:
if (Gdx.input.justTouched()) {
Vector3 intersection = new Vector3();
Ray pickRay = perspectiveCamera.getPickRay(Gdx.input.getX(), Gdx.input.getY());
Intersector.intersectRayBounds(pickRay, modelBounds, intersection);
}
and then intersection should give me the point where they overlap. It appears to be not working, however, giving me really small numbers like (4.8066642E-5, 2.9180354E-5, 1.0) .. hmmm..
I have a game that is almost done but I forgot about gravity and impulse, i did not want to implement box2d and i got the gravity to work, but can some body explain how to apply an impulse without box2d?
You can simulate an impulse just by adding a velocity to the objects velocity. Like that:
class GameObject {
private Vector2 velocity = new Vector2();
public void applyImpulse(Vector2 impulse) {
velocity.add(impulse);
}
public void update(float deltaTime) {
float dampingPerSecond = 0.5f;
float dampingFactor = Math.max(0f, 1 - deltaTime*dampingPerSecond);
velocity.scl(dampingFactor);
}
}
Now you might use it like this: object.applyImpulse(new Vector2(3, 2));. In case you update all your GameObjects in every frame, your object will slow down after an impulse was given. Which is what you would expect to happen, if no further impulses hit your object. Doing this in a realistic way though is difficult and might only be achieved by using box2d. You might however tweak that and hope that it will work in your game. Remember to always apply your gravity after that though.
I'm writing a bomberman game in Java and I have already wrote the code for the map of the game (which contains tiles), the players (and their movement in the map) and now I am stuck in the code for the bomb explosion.
I have a Map class which contains a 2d array of Tiles, which can contain Players, Blocks and Bombs.
The Player object have a method dropBomb who calls the method receiveBomb from the Map object (every Player has the reference of the Map object) with the position of the bomb and the bomb. When the Map method receiveBomb is called, the map put the bomb in the correct Tile.
My problem is in the explosion of the bomb. Who should care about it? The bomb itself? If it is, should the bomb have the reference for the Tile that contains it? Until now my tile haven't need the Map reference.
One possibility that I thought is to have the Tile reference inside the Bomb object, so, when the bomb explodes (and the bomb knows when it should explode) it calls a method in the tile object for the explosion and the tile calls a method in the map. By the way, I don't know this is a good idea. What should I do?
public class Tile {
private boolean available; //if the tile is not occupied by a indestructible block or bomb
private List<Entity> entities; //you can have more than one player at a tile
public boolean receiveEntity(Entity entity) {
boolean received = false;
if (available) {
this.entities.add(entity);
received = true;
if (entity instanceof Block || entity instanceof Bomb) {
available = false;
}
}
return received;
}
public boolean removePlayer(Player player) {
return entities.remove(player);
}
}
Player class:
public class Player implements Entity {
private Map gameMap;
private int posX;
private int posY;
private int explosionRange; //the explosion range for bombs
public Player(int posX, int posY, Map gameMap) {
this.gameMap = gameMap;
this.posX = posX;
this.posY = posY;
this.explosionRange = 1;
}
public void dropBomb() {
gameMap.receiveBomb(new Bomb(explosionRange), posX, posY);
}
}
Map class:
public class Map {
private Grid<Tile> tileGrid;
private int width;
private int height;
public Map(int width, int height, BuildingStrategy buildingStrategy) {
this.width = width;
this.height = height;
this.tileGrid = new Grid<Tile>(width, height);
buildingStrategy.buildMap(this);
}
public void receiveBomb(Bomb bomb, int posX, int posY) {
tileGrid.get(posX, posY).receiveEntity(bomb);
}
}
I have omitted the movement methods, because the movement is already fine.
I have always learned, and live by the rule "the table paints itself". The painter might choose the color and call the method, the floor might decide how the leaks and splatter is shown, but the table paints itself.
Back to your issue: the bomb explodes itself. This way you can have different effects of different bombs. The bomb has an effect on the tile, and the tile reacts to that.
Example: A bomb has a force and a type of explosion. The bomb, (occupying one and one tile only I think?) will 'give' it's effect to a tile.
Now it's the tile that deals with distributing this force. Lets say you have several kinds of bombs, one power (lets say a number between 1 and 10), and two type (lets say normal, incendiary, freeze).
Now your bomb explodes, and because your avatar is a level 5 fire-mage, your bombs are of power 4 and type incendiary. So you say to your tile: I explode with power 4 and I am setting you on fire!
Now the tile comes in to play. Any tile that gets 'touched' by the force of an explosion needs to call it's "Exploded" function to do stuff. If it is also on fire, there is more to do in the "onFire" function
What tiles are 'exploded' comes from force. Normal tiles with force 4 will give the expotion off to all squares within a range of 4, but if it is a special tile (it knows that from itself), like a mountain tile, it might not be able to advance with that force.
Tile 1 explodes with 4 and gives it to adjacent tiles with force 3. One of those tiles might be a wall, so doens't do anything further. Another is a normal tile, and explodes, and continues giving it forward with force 2, etc. If it is a 'water' tile, the explosion is pushed ofrward, but the fire isn't, etc
so:
bomb explodes itself and gives calls the tiles explosion function
tile is exploded and pushes explosion forward according to tile-type.
subsequent tiles explode because of this.
In the end it might look like most of the work is done by the tiles, and this is probably even the case. but the first steps: the calculation of the force, type, and the first calls are from the bomb. The bomb explodes. And then the explosion has an effect on the tile. The tile handles that, and if needed propagates it.
Your Map should be responsible for the explosion, as it is for every other tile on the map. After all, what is an explosion if not for another tile-type that disappears after a few seconds?
When your game loop calls the update method on the Map object your map should figure out:
What tile is the bomb on
Ask the bomb how far the reach is
Figure out what's in the adjacent tiles that the bomb can reach
Think of your design as a series of events, taken care of one by one in the game loop before eventually being drawn. When your bomb is dropped, it raises an event to the Map in the form of recieveBomb() with the Map being the event controller.
I believe this question fits better in a discussion format and not a Q&A format. It's hard to tell you what is the "correct design" without understanding the overall architecture.
The Map should be the responsible one for handling a bomb explosion.
I would suggest having a queue in the Map, that contains all the bombs present. Also, your bombs should have a timer (i.e., CreationTime) so that as bombs get pushed into the queue, you check each bomb in the queue for how long they have been in there and if applicable "explode" them.
Add a ExplodeBomb function in the Map that checks all 4 directions and handle the tiles accordingly.
I am trying to re-create Pong using LibGDX and Box2D. I have 2 problems, if I fix one it creates another.
My paddles are currently set to Kinematic and are controlled using the up/down keys via a controller class. This works just fine and I can happily play back and forth.
Problem being, my walls are static bodies and my paddles just travel right through them.
Now I can fix this by simple changing the paddle body to a dynamic one, this stops the paddles from going through the walls but then when my ball strikes off a paddle, it goes flying off the X axis and off the screen.
I have tried adding an update method in my controller class as follows:
public void update(float delta){
paddleBodyPosY = paddleBody.getPosition().x;
paddleBodyPosY = paddleBody.getPosition().y;
System.out.println(paddleBodyPosY);
}
The console reports the paddle position being updated every frame, from top to bottom of screen.
So I went back to my GameScreen class and tried all sorts of code in the Render() method like so:
if(playerOnePaddle.paddleBodyPosY < 0){
playerOnePaddle.paddleBody.getPosition().y = 0;
System.out.println("resetting paddle");
}
I have tried LOADS of variations, I can easily break movement by calling paddleBody.setLinearVelocity(0,0) but then it gets stuck like this and it's not movable anymore. Obviously the problem must lie with the fact that I can't set a position using a getter lol.
Any ideas? If you need more snippets ask, I didn't want to overload the question with 100 lines of code you don't need to see :S.
The paddle creation method:
public void createPaddle(World world, float x, float y){
//Define a body for the paddle
BodyDef paddleBodyDef = new BodyDef();
paddleBodyDef.type = BodyType.KinematicBody;
paddleBodyDef.position.set(x, y);
//Define a shape for the paddle
PolygonShape paddleShape = new PolygonShape();
paddleShape.setAsBox(paddleWidth, paddleHeight);
//Define a fixture for the paddle
FixtureDef paddleFixtureDef = new FixtureDef();
paddleFixtureDef.shape = paddleShape;
paddleFixtureDef.density = 0;
//Ensures ball bounces off paddle
//Consistently without losing velocity
paddleFixtureDef.restitution = 1.005f;
//Create the paddles
paddleBody = world.createBody(paddleBodyDef);
paddleFixture = paddleBody.createFixture(paddleFixtureDef);
paddleShape.dispose();
}
Heh, so what I did was.
Set my paddles to dynamic, then set there mass to a stupidly high number so that the a ball would not move them on the x axis, well not enough for the human eye to see at least.
Seems like a cheap fix, if anyone has anything better...that would be great lol