java libgdx move perspective camera

Question

I'm creating a 3D game but I don't know how to translate the camera according to my fingers. I'm creating a map(x = -30 to +30;y = -30 to 30;z = -1 to 1) where every coordinate is used for a model using .g3db files from my assets and put in place using model translation. This works so far, the map looks good and is viewed in a 67% angle. The map is so large it can't be viewed in the camera at once(no I don't want to zoom out). Whenever I'm touching the screen of my android phone it's just rotating around the center, but instead I want the gamemap to stay in place from my point of view and instead change the position of the perspective camera on the x and y axis. There's no game object that can be used for position tracking, everything should be depending on my finger actions. This way I want to move to visible screen to each x and y direction(think of it visualy like a 2D camera moving up, down and to the sides in front of a picture). Can you help me?

This is my code so far:

public class MyGdxGame extends ApplicationAdapter implements ApplicationListener{
//define variables
...
@Override
public void create() {
    environment = new Environment();
    environment.set(new ColorAttribute(ColorAttribute.AmbientLight, 0.4f, 0.4f, 0.4f, 1f));
    environment.add(new DirectionalLight().set(0.8f, 0.8f, 0.8f, -1f, -0.8f, -0.2f));

    modelBatch = new ModelBatch();

    cam = new PerspectiveCamera(67, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    cam.position.set(10f, 10f, 10f);
    cam.lookAt(0,0,0);
    cam.near = 1f;
    cam.far = 300f;
    cam.update();

    assets = new AssetManager();
    //load assets
    ...
    loading = true;        
    camController = new CameraInputController(cam);
    camController.forwardTarget = true;
    Gdx.input.setInputProcessor(camController);      
}

private void doneLoading() {
//load models and add them to instances
loading = false
}

    @Override
public void render() {
    if (loading && assets.update())
        doneLoading();
    camController.update();

    Gdx.gl.glViewport(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight());
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT | GL20.GL_DEPTH_BUFFER_BIT);

    modelBatch.begin(cam);
    modelBatch.render(instances, environment);
    modelBatch.end();
}

I'm using the spring tool suite 3.5.1 as IDE and libgdx 1.0.1

Answer 1

Dont use a CameraInputController, but instead implement InputProcessor and use that class in the call to Gdx.input.setInputProcessor.

For example:

public class MyGdxGame extends ApplicationAdapter implements InputProcessor {

And in the create method:

Gdx.input.setInputProcessor(this);

You'll have to implement all methods as shown in this link, except for the touchDown and touchDragged method which require additional code:

private int dragX, dragY;
@Override
public boolean touchDown (int x, int y, int pointer, int button) {
    dragX = x;
    dragY = y;
    return true;
}

@Override
public boolean touchDragged (int x, int y, int pointer) {
    float dX = (float)(x-dragX)/(float)Gdx.graphics.getWidth();
    float dY = (float)(dragY-y)/(float)Gdx.graphics.getHeight();
    dragX = x;
    dragY = y;
    cam.position.add(dX * 10f, dY * 10f, 0f);
    cam.update();
    return true;
}

Here the dX and dY values is the amount that user has dragged on the screen within the range between -1f and +1f. E.g. for dX a value of 0.5f means that the user dragged half the screen size to the right. Note that these are delta values since the last time the method was called. The method is likely to be called many times per drag operation. Therefor, the dX and dY will be small values.

The call to cam.position.add(...) will actually move the camera and the call to cam.update(); will recalculate the values needed for rendering. I've used a multiplier of 10f for both the X and Y translation of the camera. This means that if the user fully drags from the left edge to the right edge of the screen, that the camera will move a total amount of 10 units to the right. You can adjust the value as needed.

Note that this moves the camera on XY plane. If you need to move on e.g. the XZ plane, you need to adjust the call the cam.position.add(...) accordingly. Also, this doesn't change the direction of the camera. If you want to move the camera, while looking at the same location, you'll need to add cam.lookAt(0,0,0); just before cam.update();.