绘制纹理映射的矩形

Question

我想绘制2个三角形在一起作为一个矩形和绘制整个纹理，我认为只是1.0坐标。我得到了一个有很多微小褪色纹理的三角形。我对opengl非常陌生，对于这些调用正在发生什么。 有没有人看到任何明显错误可能在我的QUAD类中，就像我有错误的坐标或错误的顺序绘图？

public class MyRenderer implements GLSurfaceView.Renderer { 
     private Quad myquad; 
     private Context context; 
     int texture[] = new int[1]; 
     private int width,height; 
     int x,y; 
     private long startframe,timediff,sleeptime,frameskip; 
     private final static int MAX_FPS = 25; 
     private final static int MAX_FRAME_SKIPS = 5; 
     private final static int FRAME_PERIOD = 1000/MAX_FPS; 
     private static Direction move_direction=Direction.NONE; 


     public MyRenderer (Context context){ 
      this.myquad = new Quad(); 
      this.context = context; 
     } 
     public void onSurfaceCreated(GL10 gl, EGLConfig config) { 
      myquad.loadGLTexture(gl, this.context); 

      //turn on alpha blending 
      gl.glEnable(GL10.GL_BLEND); 
      gl.glBlendFunc(gl.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA); 

      gl.glEnable(GL10.GL_TEXTURE_2D); 
      gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); 
      gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
      gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_FASTEST); 
      gl.glDisable(GL10.GL_DEPTH_TEST); 

      x=y=0; 
     } 

     public void onSurfaceChanged(GL10 gl, int w, int h) { 
      width=w; 
      height=h; 
      gl.glViewport(0, 0, w, h); 
      gl.glMatrixMode(GL10.GL_PROJECTION); //Select The Projection Matrix   
      gl.glLoadIdentity(); 
      gl.glOrthof(0.0f, 320, 0.0f, 480, 1.0f, -1.0f);   
     } 

     public void onDrawFrame(GL10 gl) { 
      startframe=SystemClock.elapsedRealtime(); 
      // define the color we want to be displayed as the "clipping wall" 
      gl.glClearColor(0.0f, 0.0f, 0.0f, 1.0f); 
      // clear the color buffer to show the ClearColor we called above... 
      gl.glClear(GL10.GL_COLOR_BUFFER_BIT); 
      // gl.glLoadIdentity(); 
      switch (move_direction) 
      { 
      case UP: 
       gl.glTranslatef(0, 1, 0); 
       y=y+1; 
       break; 
      case DOWN: 
       gl.glTranslatef(0, -1, 0); 
       y= y-1; 
       break; 
      case LEFT: 
       gl.glTranslatef(-1, 0, 0); 
       x=x-1; 
       break; 
      case RIGHT: 
       gl.glTranslatef(1, 0, 0); 
       x=x+1; 
       break; 
      case NONE: 
       //gl.glTranslatef(0, 0, 0); 
       break; 
      } 
      myquad.Draw(gl); 

class Quad { 
    private FloatBuffer vertices; 
    private int[] textures = new int[1]; 
    private ShortBuffer indexbuffer; 
    //private float vertices[] = { 
    //  50.0f, 50.0f, // 0. 
    //   100.0f, 50.0f, // 1. 
    //  100.0f, 100.0f, // 2. 
    //   50.0f, 100.0f // 3. 
    //}; 

    private float texture[] = {   
      0.0f, 0.0f, //0 
      1.0f, 0.0f, //1 
      1.0f, 1.0f,  //2 
      1.0f, 0.0f  //3 
    }; 

    private short indices[] = {0,1,2,0,3,2}; 



       public Quad(){ 
       try 
      { 
        float[] coords={50.0f, 50.0f, //0 
        300.0f,50.0f, //1 
        300.0f, 300.0f, //2 
        300.0f, 50.0f}; //3 

      short[] indices = {0,1,2,0,3,2}; 

      ByteBuffer verticesbuffer =  ByteBuffer.allocateDirect(coords.length*4); 
      verticesbuffer.order(ByteOrder.nativeOrder()); 
      vertices = verticesbuffer.asFloatBuffer(); 
      vertices.put(coords); 
      //vertices.position(0); 
      vertices.flip(); 

     ByteBuffer idb = ByteBuffer.allocateDirect(indices.length * 2); 
     idb.order(ByteOrder.nativeOrder()); 
     indexbuffer = idb.asShortBuffer(); 
     indexbuffer.put(indices); 
     //indexbuffer.position(0); 
     indexbuffer.flip(); 
     }catch(Exception e) 
     { 
      Log.d("buffers","not working",e); 
     } 
    } 

    public void loadGLTexture(GL10 gl, Context context) { 
      //Get the texture from the Android resource directory 
      //Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),R.drawable.herowalkback); 
     try 
     { 
     Bitmap bitmap = BitmapFactory.decodeResource(context.getResources(),R.drawable.herowalkback); 

      if (bitmap == null) 
      { 
       Log.i ("info", "bitmap could not be decoded"); 
      } 
      //Generate one texture pointer... 
      gl.glGenTextures(1, textures, 0); 
      //...and bind it to our array 
      gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[0]); 

      //Create Nearest Filtered Texture 
      gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST); 
      gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_NEAREST); 

      gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE, GL10.GL_REPLACE); 

      //Use the Android GLUtils to specify a two-dimensional texture image from our bitmap 
      GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0,bitmap, 0); 

      //Clean up 
      bitmap.recycle(); 
     }catch(Exception e) 
     { 
      Log.d("load texture","not working"); 
     } 
     } 

    public void Draw(GL10 gl) 
    { 
     // set the color for the triangle 
     gl.glColor4f(0.0f, 1.0f, 0.0f, 0.5f); 

     //Enable the vertex and texture state 
     vertices.position(0); 
     gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vertices); 
     vertices.position(2); 
     gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, vertices); 


     // Draw the vertices as triangle strip 
     gl.glDrawElements(GL10.GL_TRIANGLES, 6, GL10.GL_UNSIGNED_SHORT, indexbuffer); 

    } 
} 


public class test extends Activity { 
    private GLSurfaceView glsurface; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     glsurface = new GLSurfaceView(this); 
     glsurface.setRenderer(new MyRenderer(this)); 
     setContentView(glsurface); 
     glsurface.setOnKeyListener(watchkeys); 
     glsurface.setFocusable(true); 
     glsurface.setFocusableInTouchMode(true); 


    } 

Answer 1

你没有做错什么。这就是所谓的纹理贴图，你需要习惯这种情况。

因此，例如，记住要使用0.0和1.0水平地绘制一个三角形（x坐标）。如果涉及两个三角形，则需要相应地分割坐标。所以它是0.0,0.5,1.0。对于Y轴也是如此。

理想情况下，您会使用像Blender这样的建模工具来纹理贴图对象，因此您不必担心将1.0划分为x个三角形。