浮動緩衝區破壞問題

Question

我正在編寫基於DooM地圖佈局的3D渲染器/引擎並將其移植到Android。我原來的算法非常慢，我使用方法ID爲他們的iPhone端口做了改進。這是函數：

public void renderScene(GL10 gl, Map map) { 
    int currentTexture = renderWalls[0].texID; 
    gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[currentTexture]); 

    cFrame.reset(); 

    for (int i = 0; i < numWalls; i++) { 
     Wall wall = renderWalls[i]; 

     // Draw if texture change 
     if (wall.texID != currentTexture) { 
      cFrame.transfer(); 
      gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); 
      gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
      gl.glVertexPointer(3, GL10.GL_FLOAT, 4 * 5, cFrame.verts); 
      // Create a buffer that points 3 floats past the beginning. 
      FloatBuffer texData = cFrame.verts.duplicate(); 
      texData.position(3); 
      gl.glTexCoordPointer(2, GL10.GL_FLOAT, 4 * 5, texData); 
      gl.glDrawElements(GL10.GL_TRIANGLE_STRIP, cFrame.numIndices, 
        GL10.GL_UNSIGNED_SHORT, cFrame.indices); 
      gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
      gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); 
      cFrame.reset(); 
      currentTexture = wall.texID; 
      gl.glBindTexture(GL10.GL_TEXTURE_2D, textures[currentTexture]); 
     } 

     cFrame.vertices[(cFrame.numVerts * 5)] = wall.p1.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 1] = wall.top; 
     cFrame.vertices[(cFrame.numVerts * 5) + 2] = wall.p1.y; 

     cFrame.vertices[(cFrame.numVerts * 5) + 3] = wall.uv1.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 4] = wall.uv1.y; 

     cFrame.numVerts++; 

     cFrame.vertices[(cFrame.numVerts * 5)] = wall.p1.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 1] = wall.bottom; 
     cFrame.vertices[(cFrame.numVerts * 5) + 2] = wall.p1.y; 

     cFrame.vertices[(cFrame.numVerts * 5) + 3] = wall.uv2.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 4] = wall.uv2.y; 

     cFrame.numVerts++; 

     cFrame.vertices[(cFrame.numVerts * 5)] = wall.p2.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 1] = wall.top; 
     cFrame.vertices[(cFrame.numVerts * 5) + 2] = wall.p2.y; 

     cFrame.vertices[(cFrame.numVerts * 5) + 3] = wall.uv3.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 4] = wall.uv3.y; 

     cFrame.numVerts++; 

     cFrame.vertices[(cFrame.numVerts * 5)] = wall.p2.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 1] = wall.bottom; 
     cFrame.vertices[(cFrame.numVerts * 5) + 2] = wall.p2.y; 

     cFrame.vertices[(cFrame.numVerts * 5) + 3] = wall.uv4.x; 
     cFrame.vertices[(cFrame.numVerts * 5) + 4] = wall.uv4.y; 

     cFrame.numVerts++; 

     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 2); 
     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 3); 
     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 4); 
     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 3); 
     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 2); 
     cFrame.indexes[cFrame.numIndices++] = (short) (cFrame.numVerts - 1); 
    } 
    cFrame.transfer(); 
    gl.glEnableClientState(GL10.GL_VERTEX_ARRAY); 
    gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
    gl.glVertexPointer(3, GL10.GL_FLOAT, 4 * 5, cFrame.verts); 
    // Create a buffer that points 3 floats past the beginning. 
    FloatBuffer texData = cFrame.verts.duplicate(); 
    texData.position(3); 
    gl.glTexCoordPointer(2, GL10.GL_FLOAT, 4 * 5, texData); 
    gl.glDrawElements(GL10.GL_TRIANGLES, cFrame.numIndices, 
      GL10.GL_UNSIGNED_SHORT, cFrame.indices); 
    gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY); 
    gl.glDisableClientState(GL10.GL_VERTEX_ARRAY); 
} 

我經歷了BSP樹和收集哪條線路將呈現。這些被放入牆的數組（存儲vert和tex coords/id）並通過紋理id快速排列。然後運行以下函數。

我把問題的範圍縮小到前3個問題的腐敗問題。前三個是一些奇怪的浮點值，其餘的都是正常的。

cFrame對象計算垂直/索引的數量並從數組傳遞到floatbuffer。這裏是類/函數

class CurrentFrame { 
    public short numVerts, numIndices; 
    public FloatBuffer verts; 
    public ShortBuffer indices; 

    public float vertices[]; 
    public short indexes[]; 

    public CurrentFrame(int maxVal) { 
     ByteBuffer vertsBB = ByteBuffer.allocateDirect(maxVal * 4); 
     vertsBB.order(ByteOrder.nativeOrder()); 
     verts = vertsBB.asFloatBuffer(); 

     ByteBuffer indBB = ByteBuffer.allocateDirect(maxVal * 2); 
     indBB.order(ByteOrder.nativeOrder()); 
     indices = vertsBB.asShortBuffer(); 

     vertices = new float[maxVal]; 
     indexes = new short[maxVal]; 
    } 

    public void reset() { 
     cFrame.numIndices = 0; 
     cFrame.numVerts = 0; 
     cFrame.verts.position(0); 
     cFrame.indices.position(0); 
    } 

    public void transfer() { 
     verts.position(0); 
     indices.position(0); 
     verts.put(vertices, 0, numVerts * 5); 
     indices.put(indexes, 0, numIndices); 
     verts.position(0); 
     indices.position(0); 
    } 
} 

Answer 1

想通了，索引指向vertBB而不是indBB，導致腐敗。

verts = vertsBB.asFloatBuffer(); 
    indices = vertsBB.asShortBuffer();