DIRECT3D 中绘制立方体的问题

sh308178685

程序一

CUSTOMVERTEX Vertices[] =
    {
        { -1.0f,-1.0f, -1.0f, D3DCOLOR_XRGB(255,0,0)},
         { -1.0f,1.0f, -1.0f, D3DCOLOR_XRGB(0,255,0) },
        { 1.0f,1.0f, -1.0f, D3DCOLOR_XRGB(0,0,255) },
   { 1.0f,-1.0f, -1.0f, D3DCOLOR_XRGB(255,255,0) },
    { -1.0f,-1.0f, 1.0f, D3DCOLOR_XRGB(255,0,255)},
     { -1.0f,1.0f, 1.0f, D3DCOLOR_XRGB(0,255,255)},
      { 1.0f,1.0f, 1.0f, D3DCOLOR_XRGB(0,0,0)},
    { 1.0f,-1.0f, 1.0f, D3DCOLOR_XRGB(255,255,255) }
    };



WORD* indices = 0;
g_pIB->Lock(0,0,(void**)&indices,0);
indices[0]  = 0; indices[1]  = 1; indices[2]  = 2;
indices[3]  = 0; indices[4]  = 2; indices[5]  = 3;

// back side
indices[6]  = 4; indices[7]  = 6; indices[8]  = 5;
indices[9]  = 4; indices[10] = 7; indices[11] = 6;

// left side
indices[12] = 4; indices[13] = 5; indices[14] = 1;
indices[15] = 4; indices[16] = 1; indices[17] = 0;

// right side
indices[18] = 3; indices[19] = 2; indices[20] = 6;
indices[21] = 3; indices[22] = 6; indices[23] = 7;

// top
indices[24] = 1; indices[25] = 5; indices[26] = 6;
indices[27] = 1; indices[28] = 6; indices[29] = 2;

// bottom
indices[30] = 4; indices[31] = 0; indices[32] = 3;
indices[33] = 4; indices[34] = 3; indices[35] = 7;
g_pIB->Unlock();

程序二



// 前面
vground[0] = Vertex(-1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f);
vground[1] = Vertex(-1.0f,  1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f);
vground[2] = Vertex( 1.0f,  1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f);
vground[3] = Vertex( 1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f);

// 后面
vground[4] = Vertex(-1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f);
vground[5] = Vertex( 1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f);
vground[6] = Vertex( 1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f);
vground[7] = Vertex(-1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f);

// 上面
vground[8]  = Vertex(-1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f);
vground[9]  = Vertex(-1.0f, 1.0f,  1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f);
vground[10] = Vertex( 1.0f, 1.0f,  1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f);
vground[11] = Vertex( 1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f);

// 底面
vground[12] = Vertex(-1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f);
vground[13] = Vertex( 1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f);
vground[14] = Vertex( 1.0f, -1.0f,  1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f);
vground[15] = Vertex(-1.0f, -1.0f,  1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f);

// 左面
vground[16] = Vertex(-1.0f, -1.0f,  1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f);
vground[17] = Vertex(-1.0f,  1.0f,  1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f);
vground[18] = Vertex(-1.0f,  1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f);
vground[19] = Vertex(-1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f);

// 右面
vground[20] = Vertex( 1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f);
vground[21] = Vertex( 1.0f,  1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f);
vground[22] = Vertex( 1.0f,  1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f);
vground[23] = Vertex( 1.0f, -1.0f,  1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f);

Mesh->UnlockVertexBuffer();



WORD* i = 0;
Mesh->LockIndexBuffer(0, (void**)&i);

// 前面
i[0] = 0; i[1] = 1; i[2] = 2;
i[3] = 0; i[4] = 2; i[5] = 3;

// 后面
i[6] = 4; i[7]  = 5; i[8]  = 6;
i[9] = 4; i[10] = 6; i[11] = 7;

// 上面
i[12] = 8; i[13] =  9; i[14] = 10;
i[15] = 8; i[16] = 10; i[17] = 11;

// 底面
i[18] = 12; i[19] = 13; i[20] = 14;
i[21] = 12; i[22] = 14; i[23] = 15;

// 左面
i[24] = 16; i[25] = 17; i[26] = 18;
i[27] = 16; i[28] = 18; i[29] = 19;

// 右面
i[30] = 20; i[31] = 21; i[32] = 22;
i[33] = 20; i[34] = 22; i[35] = 23;
问题1
为什么都是绘制立方体 程序一只用了8个顶点，索引缓存36个点种重复利用这8个点，而程序二定义了24个点，索引缓存还是36个点重复利用这个24个顶点 有什么区别
问题2
我知道第二个程序增加了每个顶点的法向量 怎么有些点的坐标一样 法向量却不一样呢？