LibGDX平移有时会跳跃

debugcn 发表于 Dev

罗宾·埃勒克曼（Robin Ellerkmann）

我正在开发一款基于图块的游戏，该游戏应该可以滚动，但只能在世界范围内进行。因此，我根据几个示例/教程的建议设置了pan（）方法，但它并不总是能够正常工作。有时，它会跳回到上一个手势的起点，或者移动得非常缓慢。此外，边框也不起作用。也许有人可以指出我犯的错误。

public void pan(float x, float y, float deltaX, float deltaY) { 
    moveCamera(x, y);   
}   

private void moveCamera(float x, float y) {
    Vector3 new_position = getNewCameraPosition((int) x, (int)y);

    if(!cameraOutOfLimit(new_position)) 
        this.getViewport().getCamera().translate(new_position.sub(this.getViewport().getCamera().position));

    lastTouchDown.set(x, y, 0);
}

private Vector3 getNewCameraPosition(int x, int y) { 
    Vector3 newPosition = lastTouchDown;        
    newPosition.sub(x, y, 0);   
    newPosition.y = -newPosition.y;     
    newPosition.add(this.getViewport().getCamera().position);

    return newPosition;
}

private boolean cameraOutOfLimit( Vector3 position ) {
    int x_left_limit = (int) (Global.SCREEN_WIDTH / 2);
    int x_right_limit = (int) (Global.COLS_OF_TILES * Global.TILE_WIDTH - (Global.SCREEN_WIDTH / 2));
    int y_bottom_limit = (int) (Global.SCREEN_HEIGHT / 2);
    int y_top_limit = (int) (Global.ROWS_OF_TILES * Global.TILE_HEIGHT - Global.SCREEN_HEIGHT / 2);

    if( position.x < x_left_limit || position.x > x_right_limit )
        return true;
    else if( position.y < y_bottom_limit || position.y > y_top_limit )
        return true;
    else
        return false; 
}

Tenfour04

上面的代码对我来说似乎很复杂，我真的不明白为什么您要修改一个lastTouchPosition与触摸位置无关的矢量。

我会做这样的事情。每当您要移动相机时，这些方法都会锁定目标X和Y位置。

float clampCamTargetX(float x) {
    x = Math.max(x, (int) (Global.SCREEN_WIDTH / 2));
    x = Math.min(x, (int) (Global.COLS_OF_TILES * Global.TILE_WIDTH - (Global.SCREEN_WIDTH / 2)));
    return x;
}

float clampCamTargetY (float y){
    y = Math.max(y,(int)(Global.SCREEN_HEIGHT/2));
    y = Math.min(y,(int)(Global.ROWS_OF_TILES*Global.TILE_HEIGHT-Global.SCREEN_HEIGHT/2));
    return y;
}

然后，如果要平移它，您将执行以下操作：

void panCamera(float deltaX, float deltaY) {
    Camera camera = this.getViewport().getCamera();
    Vector3 camPosition = camera.position;
    camPosition.x = clampCamTargetX(camPosition.x + deltaX);
    camPosition.y = clampCamTargetY(camPosition.y + deltaY);
    camera.update();
}

或者，如果您想要一个完整的解决方案以将相机平稳地移动到最后触摸的位置，请尝试以下操作：

float startXCam, startYCam, targetXCam, targetYCam;
float elapsedTimeCam;
boolean panningCam = false;
static final float CAM_PAN_DURATION = 0.4f;

public void render (){
    //...
    panCameraToTouchPoint(Gdx.graphics.getDeltaTime());
    //...
}

void panCameraToTouchPoint (float deltaTime){
    Camera camera = getViewport().getCamera();
    Vector3 camPosition = camera.position;
    if (Gdx.input.justTouched()) {
        startXCam = camPosition.x;
        startYCam = camPosition.y;
        targetXCam = clampCamTargetX(Gdx.input.getX());
        targetYCam = clampCamTargetY(Gdx.input.getY());
        elapsedTimeCam = 0;
        panningCam = true;
    }

    if (panningCam){
        elapsedTimeCam += deltaTime;
        float alpha = elapsedTimeCam / CAM_PAN_DURATION;
        if (alpha >= 1){
            alpha = 1;
            panningCam = false;
        }
        camPosition.x = Interpolation.pow2Out.apply(startXCam, targetXCam, alpha);
        camPosition.y = Interpolation.pow2Out.apply(startYCam, targetYCam, alpha);
        camera.update();
    }
}