無法讓opengl ES在Android上以2D繪製任何東西

Question

這是我爲了使2D繪圖工作而編寫的代碼。活動以及視圖和渲染器的設置都是正確的。我得到一個完全黑色的屏幕，但沒有多邊形。沒有畫。這是關於我逼瘋......

public class OpenGLActivity extends Activity { 

    private GLSurfaceView surfaceView; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 

     requestWindowFeature(Window.FEATURE_NO_TITLE); 
     getWindow().setFlags(
       WindowManager.LayoutParams.FLAG_FULLSCREEN, 
       WindowManager.LayoutParams.FLAG_FULLSCREEN 
       ); 

     this.surfaceView = new OpenGLSurfaceView(this); 
     setContentView(this.surfaceView); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     surfaceView.onPause(); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     surfaceView.onResume(); 
    } 
} 

public class OpenGLSurfaceView extends GLSurfaceView { 

    private OpenGLSurfaceRenderer renderer; 

    public OpenGLSurfaceView(Context context) { 
     super(context); 
     this.renderer = new OpenGLSurfaceRenderer(); 
     setRenderer(renderer); 
    } 

} 

public class OpenGLSurfaceRenderer implements Renderer { 

    private FloatBuffer vertexBuffer; 
    private float[] vertices = { 
      0.0f, 1.0f, 0.0f, 
      0.0f, 0.0f, 0.0f, 
      1.0f, 1.0f, 0.0f, 
      1.0f, 0.0f, 0.0f, 
      0.0f, 10.0f, 0.0f, 
      0.0f, 0.0f, 0.0f, 
      10.0f, 10.0f, 0.0f, 
      10.0f, 0.0f, 0.0f 
    }; 

    public OpenGLSurfaceRenderer() { 
     ByteBuffer byteBuffer = ByteBuffer.allocateDirect(vertices.length * (Float.SIZE >> 3)); 
     vertexBuffer = byteBuffer.asFloatBuffer(); 
     vertexBuffer.put(vertices); 
     vertexBuffer.position(0); 
    } 

    public void onSurfaceCreated(GL10 gl, EGLConfig config) { 

     gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST); 

     gl.glClearColor(0.0f, 0.0f, 0.0f, 1); 
     gl.glShadeModel(GL10.GL_FLAT); 
     gl.glDisable(GL10.GL_DEPTH_TEST); 
     gl.glEnable(GL10.GL_TEXTURE_2D); 

     gl.glDisable(GL10.GL_DITHER); 
     gl.glDisable(GL10.GL_LIGHTING); 

     gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT); 
    } 

    public void onDrawFrame(GL10 gl) { 

     gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); 
     gl.glVertexPointer(3, GL10.GL_FLOAT, 0, vertexBuffer); 

     gl.glClear(GL10.GL_COLOR_BUFFER_BIT); 
     gl.glColor4f(1.0f, 1.0f, 1.0f, 1.0f); 

     gl.glTranslatef(0.0f, 0.0f, 0.5f); 
     gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4); 
    } 

    public void onSurfaceChanged(GL10 gl, int width, int height) { 

     gl.glViewport(0, 0, width, height); 

     // Clear the projection matrix 
     gl.glMatrixMode(GL10.GL_PROJECTION); 
     gl.glLoadIdentity(); 

     // Set up orthographic projection mode (2D drawing) 
     gl.glOrthof(0, width, height, 0, 0, 1); 

     gl.glMatrixMode(GL10.GL_MODELVIEW); 
     gl.glLoadIdentity(); 
    } 

} 

Answer 1

我看四個方面的問題：

1. ）的最後一個參數（4,8應該是8，而不是4.這是你的頂點數量而不是三角形條上的三角形數量。

2. 你的正射投影使你的世界單位相當於像素。您的前4個頂點描述的是1像素寬的三角形。也許你正在屏幕左下角獲得一個白色像素？

3. 您沿每個框架的Z軸推進模型投影。兩幀後，它將會出現在視野之外。

4. 最重要的是，您不要在ByteBuffer上設置正確的順序。插入此行到您的OpenGlRenderer（）構造函數：

   公共OpenGLSurfaceRenderer（）{ 的ByteBuffer字節緩衝區= ByteBuffer.allocateDirect（vertices.length * 4）; byteBuffer.order（ByteOrder.nativeOrder（））; < ------ vertexBuffer = byteBuffer.asFloatBuffer（）; vertexBuffer.put（vertices）; vertexBuffer.position（0）; }