android - 在libgdx上設置起始點左上角

Question

我想使用libgdx作爲根據屏幕縱橫比縮放應用程序的解決方案。 我找到了這個鏈接，我發現它真的有用： http://blog.acamara.es/2012/02/05/keep-screen-aspect-ratio-with-different-resolutions-using-libgdx/

我是用OpenGL（已經很多年沒有爲它寫）很生疏，我想使用這個鏈接，這樣的例子放置圖像和形狀將很容易。不幸的是，起點在中間。我想在許多其他平臺上使用它 - 左上角應該是（0,0），右下角應該是（targetWidth-1，targetHeight-1）， 我記得，我需要移動（平移）並旋轉相機以實現它，但我不確定。

這裏是我修改爲onCreate方法鏈接的例子代碼：

@Override 
public void create() 
    { 
    camera=new OrthographicCamera(VIRTUAL_WIDTH,VIRTUAL_HEIGHT); 
    // camera.translate(VIRTUAL_WIDTH/2,VIRTUAL_HEIGHT/2,0); 
    // camera.rotate(90,0,0,1); 
    camera.update(); 
    // 
    font=new BitmapFont(Gdx.files.internal("data/fonts.fnt"),false); 
    font.setColor(Color.RED); 
    // 
    screenQuad=new Mesh(true,4,4,new VertexAttribute(Usage.Position,3,"attr_position"),new VertexAttribute(Usage.ColorPacked,4,"attr_color")); 
    Point bottomLeft=new Point(0,0); 
    Point topRight=new Point(VIRTUAL_WIDTH,VIRTUAL_HEIGHT); 
    screenQuad.setVertices(new float[] {// 
     bottomLeft.x,bottomLeft.y,0f,Color.toFloatBits(255,0,0,255),// 
      topRight.x,bottomLeft.y,0f,Color.toFloatBits(255,255,0,255),// 
      bottomLeft.x,topRight.y,0f,Color.toFloatBits(0,255,0,255),// 
      topRight.x,topRight.y,0f,Color.toFloatBits(0,0,255,255)}); 
    screenQuad.setIndices(new short[] {0,1,2,3}); 
    // 
    bottomLeft=new Point(VIRTUAL_WIDTH/2-50,VIRTUAL_HEIGHT/2-50); 
    topRight=new Point(VIRTUAL_WIDTH/2+50,VIRTUAL_HEIGHT/2+50); 
    quad=new Mesh(true,4,4,new VertexAttribute(Usage.Position,3,"attr_position"),new VertexAttribute(Usage.ColorPacked,4,"attr_color")); 
    quad.setVertices(new float[] {// 
    bottomLeft.x,bottomLeft.y,0f,Color.toFloatBits(255,0,0,255),// 
     topRight.x,bottomLeft.y,0f,Color.toFloatBits(255,255,0,255),// 
     bottomLeft.x,topRight.y,0f,Color.toFloatBits(0,255,0,255),// 
     topRight.x,topRight.y,0f,Color.toFloatBits(0,0,255,255)}); 
    quad.setIndices(new short[] {0,1,2,3}); 
    // 
    texture=new Texture(Gdx.files.internal(IMAGE_FILE)); 
    spriteBatch=new SpriteBatch(); 
    spriteBatch.getProjectionMatrix().setToOrtho2D(0,0,VIRTUAL_WIDTH,VIRTUAL_HEIGHT); 
    } 

到目前爲止，我已經成功才能使用縮放座標，使用此代碼，並且仍然保持寬高比（這是很棒），但我沒有成功將起點（0,0）移到左上角。

請幫幫我。

---

編輯：好的，經過一些測試，我發現它不工作的原因是我使用spriteBatch。我認爲它忽略了相機。這段代碼出現在渲染部分。不管我對相機做什麼，它仍然會顯示相同的結果。

@Override 
public void render() 
    { 
    if(Gdx.input.isKeyPressed(Keys.ESCAPE)||Gdx.input.justTouched()) 
    Gdx.app.exit(); 
    // update camera 
    // camera.update(); 
    // camera.apply(Gdx.gl10); 
    // set viewport 
    Gdx.gl.glViewport((int)viewport.x,(int)viewport.y,(int)viewport.width,(int)viewport.height); 
    // clear previous frame 
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT); 
    // 
    final String msg="test"; 
    final TextBounds textBounds=font.getBounds(msg); 
    spriteBatch.begin(); 
    screenQuad.render(GL10.GL_TRIANGLE_STRIP,0,4); 
    quad.render(GL10.GL_TRIANGLE_STRIP,0,4); 
    Gdx.graphics.getGL10().glEnable(GL10.GL_TEXTURE_2D); 
    spriteBatch.draw(texture,0,0,texture.getWidth(),texture.getHeight(),0,0,texture.getWidth(),texture.getHeight(),false,false); 
    spriteBatch.draw(texture,0,VIRTUAL_HEIGHT-texture.getHeight(),texture.getWidth(),texture.getHeight(),0,0,texture.getWidth(),texture.getHeight(),false,false); 
    font.draw(spriteBatch,msg,VIRTUAL_WIDTH-textBounds.width,VIRTUAL_HEIGHT); 
    spriteBatch.end(); 
    } 

Answer 1

這些行：

camera.translate(VIRTUAL_WIDTH/2,VIRTUAL_HEIGHT/2,0); 
camera.rotate(90,0,0,1); 

應移動相機，使得你想要做什麼。然而，我的代碼有一個額外的：

camera.update() 

通話後調用翻譯，它看起來像你缺少。該doc for Camera.update說：

update 
public abstract void update() 

Recalculates the projection and view matrix of this camera and the Frustum planes. Use this after you've manipulated any of the attributes of the camera.