修改obj三维模型文件中坐标z为其相反数

具体做法是：打开一个obj文件，查找含有“v x y z"的字串，然后对z的字串进行符号处理：

若为"-"，直接将该符号删除；不为"-"且z值不为0，则在z的字串前加上"-"。

示例（原始文件box.obj）

#
# object Box01
#

v -39.306316 -32.828358 -29.183971
v -39.306316 33.259296 -29.183971
v 39.726025 33.259296 -29.183971
v 39.726025 -32.828358 -29.183971
v -39.306316 -32.828358 26.914204
v 39.726025 -32.828358 26.914204
v 39.726025 33.259296 26.914204
v -39.306316 33.259296 26.914204

-----------------------------------

转换后的文件（box.obj.flip）：

#
# object Box01
#

v -39.306316 -32.828358 29.183971
v -39.306316 33.259296 29.183971
v 39.726025 33.259296 29.183971
v 39.726025 -32.828358 29.183971
v -39.306316 -32.828358 -26.914204
v 39.726025 -32.828358 -26.914204
v 39.726025 33.259296 -26.914204
v -39.306316 33.259296 -26.914204

 具体代码实现：

 

#include <fstream.h>
#include <math.h>

bool work(const char* path)
{
    char chs[1000];
    double x,y,z;
    CString newPath(path);
    newPath += ".flip";
    const char* chNewPath = newPath;
    ofstream opf(chNewPath);
    if (!opf.is_open()) return false;
    ifstream pf(path);
    if (!pf.is_open()) {opf.close();return false;}

    while (!pf.eof())
    {
        pf.getline(chs, 1000, '\n');
        if (sscanf(chs, "v %lf %lf %lf", &x, &y, &z)==3)
        {
            CString strChs(chs);
            int spacePos=strChs.ReverseFind(' ');
            char c=strChs.GetAt(spacePos+1);

            opf<<(LPCTSTR)(strChs.Left(spacePos+1));
            if (c=='-')
            {
                opf<<(LPCTSTR)(strChs.Right(strChs.GetLength()-spacePos-2))<<endl;
            }
            else
            {
                if (fabs(z)>1e-6) opf<<"-";
                opf<<(LPCTSTR)(strChs.Right(strChs.GetLength()-spacePos-1))<<endl;
            }
        }
        else
        {
            opf << chs << endl;
        }
    }

    opf.close();
    pf.close();
    return true;
}