与联盟和结构混淆

Question

我正在使用这个库在PCL(Point Cloud Library,www.pointclouds.org)上开展一个项目.我可以获得我的Kinect正在查看的内容的3D表示.问题是,我正在使用这个结构:

typedef union
{
    struct
    {
            unsigned char Blue;
            unsigned char Green;
            unsigned char Red;
            unsigned char Alpha;
    };
    float float_value;
    uint32_t long_value;
} RGBValue;

我想用这个结构做的是从每种颜色中获取单个数据并将它们放在浮点数中:

float R = someCloud->points[idx].rgba.Red;   
float G = someCloud->points[idx].rgba.Green;  
float B = someCloud->points[idx].rgba.Blue;  
float A = someCloud->points[idx].rgba.Alpha;  

我得到的错误是这样的:

error C2039: 'Red' : is not a member of 'System::UInt32'*

Answer 1

您必须相应地命名您的匿名结构实例

typedef union
{
    struct
    {
        unsigned char Blue;
        unsigned char Green;
        unsigned char Red;
        unsigned char Alpha;
    } rgba;

    float float_value;
    uint32_t long_value;
} RGBValue;

然后,您可以访问成员

RGBValue v;
float R = v.rgba.Red;
float G = v.rgba.Green;
float B = v.rgba.Blue;
float A = v.rgba.Alpha;