directx中第五卷

包围盒

定义包围盒

struct BoundBox
{
    BoundBox();

    bool isPointInside(D3DXVECTOR3& p); //是否包含点

    D3DXVECTOR3 _min;
    D3DXVECTOR3 _max;
};
BoundBox::BoundBox()
{
    _min.x = FLT_MAX; //初始化最大
    _min.y = FLT_MAX;
    _min.z = FLT_MAX;

    _max.x = -FLT_MAX;
    _max.y = -FLT_MAX;
    _max.z = -FLT_MAX;
}
bool BoundBox::isPointInside(D3DXVECTOR3& p)
{
    if (p.x >= _min.x && p.y >= _min.y && p.z >= _min.z &&
        p.x <= _max.x && p.y <= _max.y && p.z <= _max.z)
    {
        return true;
    }
    else
    {
        return false;
    }
}

声明变量

ID3DXMesh* BoxMesh = 0;
BoundBox boundingBox;

创建包围盒

加载模型

bool ComputeBoundingBox(ID3DXMesh* mesh, BoundBox* box)
{
    HRESULT hr = 0;

    BYTE* v = 0;
    mesh->LockVertexBuffer(0, (void**)&v);
    //计算边界盒（第一个顶点的向量，顶点数，，每个顶点大小，最小点，最大点）
    hr = D3DXComputeBoundingBox(
        (D3DXVECTOR3*)v,
        mesh->GetNumVertices(),
        D3DXGetFVFVertexSize(mesh->GetFVF()),
        &box->_min,
        &box->_max);

    mesh->UnlockVertexBuffer();

    if (FAILED(hr))
        return false;

    return true;
}
ComputeBoundingBox(Mesh, &boundingBox);

D3DXCreateBox(
        g_pd3dDevice,
        boundingBox._max.x - boundingBox._min.x,
        boundingBox._max.y - boundingBox._min.y,
        boundingBox._max.z - boundingBox._min.z,
        &BoxMesh,
        0);

绘制包围盒

绘制模型

D3DMATERIAL9 white = white_mtrl;
white.Diffuse.a = 0.50f;

g_pd3dDevice->SetMaterial(&white);
//模拟碰撞或点击
if (boundingBox.isPointInside(D3DXVECTOR3(1, 1, 1)))
{
    g_pd3dDevice->SetRenderState(D3DRS_FILLMODE, D3DFILL_WIREFRAME);
    BoxMesh->DrawSubset(0);
    g_pd3dDevice->SetRenderState(D3DRS_FILLMODE, D3DFILL_SOLID);
}

效果