问题
I'm having problems setting my orthographic camera to the bottom left part of my screen (0,0)
public GameScreen(Main game) {
this.game = game;
Width = 200;
Height = 300;
view = new ExtendViewport(Width,Height);
camera = new OrthographicCamera(Gdx.graphics.getWidth(),Gdx.graphics.getHeight());
camera.setToOrtho(false,Width/2,Height/2);
camera.position.set(Width,Height,0);
camera.update();
play.Player1();
staple = new Stage();
staple.addActor(play);
staple.addActor(pile);
Gdx.input.setInputProcessor(staple);
}
@Override
public void render(float delta) {
Gdx.gl.glClearColor(0, 1, 1, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
Gdx.graphics.getDeltaTime();
game.getBatch().begin();
game.getBatch().setProjectionMatrix(camera.combined);
game.getBatch().end();
staple.act();
staple.draw();
}
@Override
public void resize(int width, int height) {
view.update(width,height);
view.setScreenPosition(width,height);
}
I've set my viewport as extended viewport using my width and height values I have assigned but I'm struggling to move the camera to the bottom left part of my screen (0,0) where it can focus on my images on my android device.
回答1:
Here are a little example how to use camera and viewport:
First we must define how big is our world the camera shows:
private static final int WORLD_WIDTH = 300; private static final int WORLD_HEIGHT = 250;
Our world is now 300 x 250 units (not Pixel!) big.
It's importent to think in units not in pixels!!
Now we need a OrthographicCamera, a Viewport and a SpriteBatch
OrthographicCamera camera;
Viewport viewport;
SpriteBatch batch;
@Override
public void create () {
camera = new OrthographicCamera(); // we create a OrthographicCamera
viewport = new ExtendViewport(WORLD_WIDTH, WORLD_HEIGHT, camera); // we create a new Viewport with our camera and we will display our world 300 x 250 units
batch = new SpriteBatch(); // we create a new SpriteBatch for draw our textures
}
In our render method we say the batch only to draw what we can see in our Viewport with the method setProjectionMatrix()
@Override
public void render (float delta) {
camera.update(); //update our camera every frame
batch.setProjectionMatrix(camera.combined); //say the batch to only draw what we see in our camera
batch.begin();
batch.draw(texture, 0,0); //draw our texture on point 0,0 bottom left corner
batch.end();
}
And in the resize method:
public void resize(int width, int height){
viewport.update(width, height); //update the viewport to recalculate
}
To understand why you have this issue:
In your code you never set the camera to the viewport: view = new ExtendViewport(Width,Height);
So your viewport never apply to the batch.
To render the correct way without Viewport you must know that the position of OrhographicCamera is in the center.
So when you set a Camera to position 0,0 and size 50,50 you see the world from -25 to 25 in each direction;
To use OrthographicCamera without Viewport:
public void create () {
camera = new OrthographicCamera(WORLD_WIDTH, WORLD_HEIGHT); // we create a OrthographicCamera and we will display our world 300 x 250 units
camera.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2, 0); //we set position of camera, our world point 0,0 is now the bottom left corner in the camera
batch = new SpriteBatch(); // we create a new SpriteBatch for draw our textures
texture = new Texture("badlogic.jpg");
}
public void render () {
camera.update();
batch.setProjectionMatrix(camera.combined);
batch.begin();
batch.draw(texture, 0,0);
batch.end();
}
The important point is in the resize method:
public void resize(int width, int height){
camera.viewportWidth = WORLD_WIDTH;
camera.viewportHeight = WORLD_HEIGHT * height / width;
camera.position.set(camera.viewportWidth / 2, camera.viewportHeight / 2, 0);
}
With this calculation you always see a World of 300 width and 250 * ratio of width, and height.
And exactly this calculation does the viewport for you. Depending on which Vieport (FitViewport, ScreenViewport, ExtendViewport) you use this calculation will be different, try it out.
I hope this helps you to understand how camera, viewport and Spritebatch works together.
Here are useful links to the libgdx wiki which descript the Viewport and Camera:
https://github.com/libgdx/libgdx/wiki/Viewports
https://github.com/libgdx/libgdx/wiki/Orthographic-camera
回答2:
Use camera.position.set(Width, Height, 1); instead of 0
回答3:
First you set the Camara width and height equal to the amount of pixels of the window.
camera = new OrthographicCamera(Gdx.graphics.getWidth(),Gdx.graphics.getHeight());
Then you center it at 100, 150. And move it again to 200, 300
camera.setToOrtho(false,Width/2,Height/2);
camera.position.set(Width,Height,0);
You are also using a Viewport but never make use of it.
I would recommend just using a Viewport of choice. A Viewport can take a camera so if you insist using your own camera you can create it but then also pass it to the Viewport when you construct it.
EDIT
Following is a tested minimal example.
public class TestScreen extends ScreenAdapter {
private Viewport viewport;
private ShapeRenderer sr;
public TestScreen() {
// Note that extend viewport extends it's camera so you end up with smaller or larger view of your world depending on the aspect ratio of the physical screen.
viewport = new ExtendViewport(200, 300);
viewport.apply();
System.out.println(viewport.getWorldWidth());
// Just for testing in the resize method.
viewport.getCamera().translate(0, 0, 0);
viewport.getCamera().update();
// ShapeRenderer for testing
sr = new ShapeRenderer();
sr.setAutoShapeType(true);
}
@Override
public void render(float delta) {
Gdx.gl.glClearColor(.04f, .06f, .1f, 1);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
// Draw circle at 0.0 in the world
sr.setProjectionMatrix(viewport.getCamera().combined);
sr.begin(ShapeRenderer.ShapeType.Line);
sr.circle(0, 0, 100);
sr.end();
}
@Override
public void resize(int width, int height) {
// Will center the camera in the world at half it's width and half it's height so left bottom is 0.0 as long as the camera did.
// By using true here you cannot move the camera since you order it to center on the screen and thus the circle we are drawing
// remains in the bottom left.
//viewport.update(width, height, true);
// This will just update the viewport, we moved the camera slightly to the left so the circle appears slight right from the middle.
viewport.update(width, height, false);
// So you want to start your camera centered on something but still want to move it you need to specify that center in the camera
// by either changing it's position or translating it like I did in the constructor. Unfortunately you only get to know the size
// of the world that is being displayed once this resize method did it's job so certain parts might get cut off or your world does
// not fill the screen.
}
}
来源：https://stackoverflow.com/questions/52011592/libgdx-set-ortho-camera