ポインタとOpenGLの描画に関する問題

Question

私は単純なレンダマネージャを実装しようとしています。別のクラスはクワッドを表す構造を提供し、これはレンダマネージャの頂点配列バッファにコピーされます。

しかし、コピーは動作していないようです。手動で構造体を作成して頂点配列にコピーすると、すべてがうまくレンダリングされます。しかし、コピーのどこかにすべてが間違っています。私はgdbを使ってこれを見ることができます（値は異なります）が、何が起こっているのか理解できません。

RenderManager方法

-(id)init 
{ 
    if([super init]){ 
     iva = calloc(MAX_QUADS, sizeof(quad)); 

     quad draw = { 
      0.0f,0.0f,0.0f,   0.0f,0.0f,1.0f, //Bottom left 
      1.0f,0.0f,0.0f,   0.0f,0.0f,1.0f, //Top Left 
      1.0f,1.0f,0.0f,   0.0f,0.0f,1.0f, //Top Right 
      0.0f,1.0f,0.0f,   0.0f,0.0f,1.0f, //Bottom Right 

      0.5f,0.5f,0.0f,   0.0f,0.0f,1.0f, //Center 
     }; 

私は何も描画しませんこれをコメントアウトした場合。それを使用し、私は質問に対して

 memcpy(iva, &draw, sizeof(draw)); 
     . . . OpenGl methods 

//Add the quad details to the render queue 
-(void)addDetailsToRenderQueue:(quad *)details 
{ 
    if(iva == NULL) 
     NSLog(@"Error claiming memory, something is very wrong"); 

    if(renderCount + 1 > MAX_QUADS){ 
     NSLog(@"Render buffer full, dumping..."); 
     [self render]; 
    } 

    memcpy((quad *)iva + renderCount++, &details, sizeof(quad)); 
} 

//Render the details in the render queue, for each quad we need to make two triangles. 
-(void)render 
{ 
    int counter = 0; 

    renderCount *= 5; 

    for(int i;i < renderCount;){ 
     ivaIndices[counter++] = i + 0;  // Bottom left 
     ivaIndices[counter++] = i + 1;  //Top Left 
     ivaIndices[counter++] = i + 4;  //Center 

     ivaIndices[counter++] = i + 1;  //Top Left 
     ivaIndices[counter++] = i + 2;  //Top right 
     ivaIndices[counter++] = i + 4;  //Center 

     ivaIndices[counter++] = i + 2;  //Top right 
     ivaIndices[counter++] = i + 3;  //Bottom right 
     ivaIndices[counter++] = i + 4;  //Center 

     ivaIndices[counter++] = i + 3;  //Bottom right 
     ivaIndices[counter++] = i + 0;  //Bottom Left 
     ivaIndices[counter++] = i + 4;  //Center 

     i += 5; 
    } 
    glBindVertexArrayOES(_vertexArray); 

    glDrawElements(GL_LINE_STRIP,12, GL_UNSIGNED_SHORT, ivaIndices); 

    // Reset the number of quads which need to be rendered 
    renderCount = 0; 
} 

タイルマネージャー法

@interface TileSet : NSObject 
{ 
    quad *tiles; 
    NSUInteger tileCount; 

    RenderManager *sharedRenderManager; 
} 

-(id)init 
{ 
    if([super init]){ 
     tiles = calloc(MAX_HEIGHT * MAX_WIDTH, sizeof(quad)); 
     tileCount = 0; 

     sharedRenderManager = [RenderManager sharedManager]; 
    } 
    [self fillArray]; 
    return self; 
} 

-(void)fillArray 
{ 
    int rows = 4; 
    int columns = 12; 

    for(int i = 0; i < rows;i += 2) { 
     for(int j = 0;j < columns;j += 2) { 
      quad tmp; 

      tmp.v1.x = i; 
      tmp.v1.y = j; 
      tmp.v1.z = 0.0f; 
      tmp.v1.nx = 0.0f; 
      tmp.v1.ny = 0.0f; 
      tmp.v1.nz = 1.0f; 

      tmp.v2.x = i + 1; 
      tmp.v2.y = j; 
      tmp.v2.z = 0.0f; 
      tmp.v2.nx = 0.0f; 
      tmp.v2.ny = 0.0f; 
      tmp.v2.nz = 1.0f; 

      tmp.v3.x = i; 
      tmp.v3.y = j+1; 
      tmp.v3.z = 0.0f; 
      tmp.v3.nx = 0.0f; 
      tmp.v3.ny = 0.0f; 
      tmp.v3.nz = 1.0f; 

      tmp.v4.x = i + 1; 
      tmp.v4.y = j+1; 
      tmp.v4.z = 0.0f; 
      tmp.v4.nx = 0.0f; 
      tmp.v4.ny = 0.0f; 
      tmp.v4.nz = 1.0f; 

      tmp.v5.x = i + 0.5; 
      tmp.v5.y = j + 0.5; 
      tmp.v5.z = 0.0f; 
      tmp.v5.nx = 0.0f; 
      tmp.v5.ny = 0.0f; 
      tmp.v5.nz = 1.0f; 

      memcpy((quad *)tiles + (i*j + j), &tmp, sizeof(quad)); 
      tileCount++; 
     } 
    } 
} 

//Draw the tiles in the tileset, loop through and add to renderManagers queue 
-(void)render 
{ 
for(int i = 0; i < tileCount;i++) 
    [sharedRenderManager addDetailsToRenderQueue:&tiles[0]]; 

} 

EDIT を期待してい素敵なクワッドを取得し、

NSLog(@"Tiles:%x\tDisgusting pointer math:%x",tiles,(quad *)tiles + (i*j + j)); 

を追加する与えます結果

2011-10-21 21:29:21.456 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:7316200 
2011-10-21 21:29:21.458 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73162f0 
2011-10-21 21:29:21.463 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73163e0 
2011-10-21 21:29:21.464 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73164d0 
2011-10-21 21:29:21.465 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73165c0 
2011-10-21 21:29:21.465 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:7316200 
2011-10-21 21:29:21.466 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73164d0 
2011-10-21 21:29:21.467 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:73167a0 
2011-10-21 21:29:21.470 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:7316a70 
2011-10-21 21:29:21.470 TerrainRendering[11293:fb03] Tiles:7316200 Disgusting pointer math:7316d40 

Answer 1

memcpyのオフセットは(i*MAX_HEIGHT + j)である必要があります。あなたは "i"（外側のループ）で行をジャンプし、 "j"（内側のループ）でそれらを順番に調べたいと思っています。

希望これは