I have 2 classes; A and B.
A is the character class, it contains every character detail (position...)
B is the class which get the A class and render. I need to create another object when I touch the screen. I got it, the class seems containing the new values but it doesn't renderize them.
for (A a: aa) {
shapeRenderer.begin(ShapeType.Filled);
shapeRenderer.setColor(Color.RED);
shapeRenderer.circle(a.getBoundingCircle().x, a.getBoundingCircle().y, a.getBoundingCircle().radius);
shapeRenderer.end();
}
is recommended use best names.
are you sure a.getBoundingCircle() cotains the correct data, and are you sure had objects A in aa and your program join inside the for?
and i dont look b
Ok, your problem is the new values dont be renderized.
Two options:
You not are running the loop for render the objects.
Your new values are out of the screen.
When you get the position of the touch events you get the screenx and the screeny, not the game camera coordenates, and you need convert it with unproject.
For example:
Vector3 touchPos = new Vector3(Gdx.input.getX(), Gdx.input.getY(), 0);
camera.unproject(touchPos);
touchPos now is in the game coordenates.
Related
I'm developing a game, and in the model of the application I have an 'endless' mode. A number of monsters are created, and when they die new ones are created. The monsters move and they are not always at the same place.
I would like to know how to display them: in the activity, there will be five monsters, but after that there are 4, 3, 2, 1 and 0. I would like to display them dynamically.
Welcome to Stackoverflow!
It is good practice to start with already developed game engines if you want to develop games on Android. But its not essential. You can still develop simple games with raw Android.
To do so, you need to have a clear concept on how view and related APIs works.
I will recommend you to explore http://developer.android.com/training/custom-views/custom-drawing.html
In your case,
Game game = new Game(Game.Settings);
game.createHero();
game.createMonsters();
while(game.playing()){
game.render();
if(game.needNewMonster()){
game.createMonster(); // at random position in view
}
}
Inside Game.java,
List<Monster> list = new ArrayList<Monster>();
void createMonster(){
list.add(new Monster("monsterA", x, y, R.drawable.monster)); // x,y are position and monster is drawable for monster. write the model code yourself
}
I create little sprites of sheeps on the top of my screen, then they should go down and after crossing bottom line they disappear. Problem is that when they are going across the screen it is very noticable that sometimes they lag. For milliseconds but its possible to see it. It happens absolutely randomly. They change their position with Gdx.graphics.getDeltaTime();
public void update (float deltaTime) {
updateMotionX(deltaTime);
updateMotionY(deltaTime);
// Move to new position
position.x += velocity.x * deltaTime;
position.y += velocity.y * deltaTime;
}
Here is the code of spawing them:
private Sheep spawnSheep(){
Sheep sheep = new Sheep();
sheep.dimension.set(dimension);
// select random cloud image
sheep.setRegion(regSheeps.random());
// position
Vector2 pos = new Vector2();
pos.x = -0.19f; // position after end of level
pos.y = 5;
sheep.position.set(pos);
//speed
Vector2 speed = new Vector2();
speed.y = 3.5f;
sheep.terminalVelocity.set(speed);
speed.y *= -1;
sheep.velocity.set(speed);
return sheep;
}
Maybe somebody already had that problem, i have no idea why it happens,
The lagging is most likely caused by garbage collection because you're continuously allocating memory within your game loop.
You want to avoid calling new whenever possible in the game loop, and if you do call new you want to reuse those objects whenever possible.
Look at pools in libgdx
http://libgdx.badlogicgames.com/nightlies/docs/api/com/badlogic/gdx/utils/Pool.html
If you're returning an object from a method, such as a Vector2, then create a static instance and reuse that object for return values. Be aware that this is not thread safe and calling the method again will overwrite the value from the first call.
If I was you I'd search for any instances of the word 'new' in your code, and make sure none of them are called frequently within the game loop. You also want to be aware of calling methods that will create instances of objects. Simple things like converting an integer to a string will waste memory, as well as more obvious things like creating a copy of an array.
You should find this useful for tracking memory allocation.
https://visualvm.java.net/
I'm starting to develop a game in libgdx, and I'm wondering what the best practice is for the following situation. There are two things that I'm trying to do at the moment: move a menu (sprite) into place, and pan the camera to the player sprite. My idea to accomplish these things is to have an 'action_stack' ArrayList in the render() function. The ArrayList would contain 'Action' instances. Each Action instance would have a step() function, which would be over-ridden. In the render() function, I would iterate through action_stack, and fire each elements' step() function. So, to accomplish moving the menu into place, I would create the class:
public class MenuAnim1 implements Action {
private int targetX;
private int targetY;
private Sprite menu;
public MenuAnim1() {
//set initial sprite and position
}
public Step() (
//move this.menu towards targetX and targetY
//draw the sprite
//if not at target position, do nothing
//if at target position, remove this object from action_stack
}
}
...and put an instance into the action_stack:
MenuAnim1 menuAnim1 = new MenuAnim1();
action_stack.add(menuAnim1);
Sorry if my Java is bad, I'm not super familiar with it. Anyways, my question is: is this even good practice? What do people normally do? Is there a better way to do what I'm describing above?
I have never used Actions, but your idea is good. If you want them to be time dependant (and thus fps independant), be sure to use the time that has passed since the last frame to the current, also known as delta or deltaTime. You can get it like this:
Gdx.graphics.getDeltaTime();
so, to make your action move the sprite, for example, to the right, this would do the trick:
speed = 10; //It will move 10 units per second.
delta = Gdx.graphics.getDeltaTime();
menu.translateX(speed*delta);
(Sprite#translateX)
I am trying Rajawali library for Android to draw some basic 3d objects on the scene.
There is a sample 2000 planes, which show how to render huge amount of vertexes very "cheaply" with one shader. I can pass array of vertexes to the shader and draw them.
I want to upgrade this sample and move some vertexes independently from each other.
I've tried glBufferSubData, but i cant change anything on the scene. The one way i've found is to change data and recreate buffer, but i hope there is a simpler way to only change the necessary data.
For example, I only want to change some positions from already created and binded buffer.
initialize positions
float[] planePositions = new float[numVertices * 3];
....
create buffer
mGeometry.createBuffer(mPlanePositionsBufferInfo, BufferType.FLOAT_BUFFER, mPlanePositions, GLES20.GL_ARRAY_BUFFER);
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
set positions
GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, planePosBufferHandle);
GLES20.glEnableVertexAttribArray(maPlanePositionHandle);
fix.android.opengl.GLES20.glVertexAttribPointer(maPlanePositionHandle, 3, GLES20.GL_FLOAT,
false, 0, 0);
and how can i modify position of, for example, the first vertex of the first plane ? (planePositions[0] = a;planePositions[1] = b; planePositions[1] = c... and now i have to pass this modified array to opengl but don't know how).
All you need to do is modify the buffer data then call mGeometry.changeBufferData() from the PlanesGalore class. I put the following code in an update method which is called during the onDrawFrame() event of my Renderer class.
for (int i = 0; i < vertices.length; i += 3) {
mPlanePositions= mPlanePositions.put(i, mPlanePositions.get(i) - 0.01f);
}
mGeometry.changeBufferData(mCubePositionsBufferInfo, mPlanePositions, 0);
This is the best way I could find for accomplishing the movements. Additionally, I have proposed a change in this issue that would let you specify what part of the buffer changed which should provide increased performance.
EDIT
My change to the engine has been approved so you can now optimize this even further like so.
// The offset position should be vertices.length * object #. In my use case this is 72*x
// allowing me to update the XYZ coordinates of all 24 vertices of a cube.
int offsetPosition = 0;
mGeometry.changeBufferData(mCubePositionsBufferInfo, mPlanePositions, offsetPosition, offsetPosition + vertices.length);
On developing a painting canvas application in android, i need to track all the points and have to redraw it in another canvas. Now i am able to track all the points, but don't know how to synchronize the point drawing in case of draw and redraw ie the user should redraw the points at the same time gap as in the draw. How can i achieve this?
Not sure if this is the sort of answer you are looking for but I would record the events with a sort of timestamp, really a time difference to the next point. Something like:
class Point {
int x;
int y;
long deltaTime;
}
Its up to you how precise you want to be with the timing. Second to millisecond precision should be good enough. You could interpret deltaTime as either the time until this point should be drawn or the time until the next point should be drawn (I'm going to use the latter in my example).
A few reasons to use a deltaTime instead of a direct timestamp is that it lets you check for really long pauses and you are going to have to compute the delta time anyways in playback. Also using it as a long should give you enough room for really lengthy pauses and lets you use the Handler class which accepts a long integer for the number of milliseconds to wait before executing.
public class Redrawer implements Handler.callback {
LinkedList<Point> points; //List of point objects describing your drawing
Handler handler = new Handler(this); //Probably should place this in class initialization code
static final int MSG_DRAW_NEXT = 0;
public void begin(){
//Do any prep work here and then we can cheat and mimic a message call
//Without a delay specified it will be called ASAP but on another
//thread
handler.sendEmptyMessage(MSG_DRAW_NEXT);
}
public boolean handleMessage(Message msg){
//If you use the handler for other things you will want to
//branch off depending on msg.what
Point p = points.remove(); //returns the first element, and removes it from the list
drawPoint(p);
if (!points.isEmpty())
handler.sendEmptyMessageDelayed(MSG_DRAW_NEXT, p.deltaTime);
public void drawPoint(Point p){
//Canvas drawing code here
//something like canvas.drawPixel(p.x, p.y, SOMECOLOR);
//too lazy to look up the details right now
//also since this is called on another thread you might want to use
//view.postInvalidate
}
This code is far from complete or bullet-proof. Namely you will need to possibly pause or restart the redrawing at a later time because the user switched activities or got a phone call, etc. I also didn't implement the details of where or how you get the canvas object (I figure you have that part down by now). Also you probably want to keep track of the previous point so you can make a rectangle to send to View.postInvalidate as redrawing a small portion of the screen is much faster than redrawing it all. Lastly I didn't implement any clean-up, the handler and points list will need to be destroyed as needed.
There are probably several different approaches to this, some probably better than this. If you're worried about long pauses between touch events simply add a check for the deltaTime if its greater than say 10 seconds, then just override it to 10 seconds. Ex. handler.sendEmptyMessage(MSG_DRAW_NEXT, Math.min(p.deltaTime, 100000)); I'd suggest using a constant instead of a hard coded number however.
Hope this helps