Question

我有以下顶点解除：

struct MESHVERTInstanced
{
    float x, y, z;      // Position
    float nx, ny, nz;   // Normal
    float tu, tv;       // Texcoord
    float idx;          // index of the vertex!
    float tanx, tany, tanz;   // The tangent

    const static D3DVERTEXELEMENT9 Decl[6];
    static IDirect3DVertexDeclaration9* meshvertinstdecl;
};

我这样声明：

const D3DVERTEXELEMENT9 MESHVERTInstanced::Decl[] =
{
    { 0, 0,  D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0 },
    { 0, 12, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL,   0 },
    { 0, 24, D3DDECLTYPE_FLOAT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 0 },
    { 0, 32, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 1 },
    { 0, 36, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TANGENT, 0 },
    D3DDECL_END()
};

我接下来要做的是将ID3DXMesh复制到另一个新的顶点声明中：

model->CloneMesh( model->GetOptions(), MESHVERTInstanced::Decl,
            gd3dDevice, &pTempMesh );

当我试图获得pTempMesh（D3DXGetFVFVertexSize（pTempMesh-＆gt; GetFVF（））的FVF大小时，我得到'0'，但大小应为48。

如果我没有最后一个声明'{0,36，D3DDECLTYPE_FLOAT3，D3DDECLMETHOD_DEFAULT，D3DDECLUSAGE_TANGENT，0}，'并且CloneMesh函数没有返回FAIL，那么整个过程都没问题。我也尝试过使用不同的声明，例如D3DDECLUSAGE_TEXCOORD，并且工作正常，返回48的大小。有什么特别关于D3DDECLUSAGE_TANGENT我不知道吗？

我完全不知道为什么这不起作用......

Answer 1

TBH AS DeadMG指出顶点decl与FVF不兼容。你问是否有另一种方法来获得顶点缓冲区的大小。您显然知道缓冲区中有多少个顶点，并且您可以明白地知道顶点结构有多大（48个字节），因为您在顶点声明中定义了顶点结构。

const D3DVERTEXELEMENT9 MESHVERTInstanced::Decl[] =
{
    { 0, 0,  D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION, 0 }, //Starts at offset 0 and is 3 floats, or 12 bytes in size.  Total = 12 bytes.
    { 0, 12, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL,   0 }, //Starts at offset 12 and is 3 floats, or 12 bytes in size.  Total = 24 bytes.
    { 0, 24, D3DDECLTYPE_FLOAT2, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 0 }, //Starts at offset 24 and is 2 floats, or 8 bytes in size.  Total = 32 bytes.
    { 0, 32, D3DDECLTYPE_FLOAT1, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD, 1 }, //Starts at offset 32 and is 1 float, or 4 bytes in size.  Total = 36 bytes.
    { 0, 36, D3DDECLTYPE_FLOAT3, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TANGENT,  0 }, //Starts at offset 36 and is 3 floats, or 12 bytes in size.  Total = 48 bytes.
    D3DDECL_END()
};

如果没有使用D3DXGetDeclLength。

Answer 2

并非每个D3DVERTEXDECL都可以转换为FVF。在尝试获取FVF大小之前，您应该三重检查您是否有与FVF兼容的声明。虽然，为什么你使用FVF超出了我的意义，但是它没有用，因为D3D10甚至不允许使用FVF。

克隆ID3DXMesh，声明有12个浮点数？

2 个答案: