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Opengl problem with texture in model from obj

Answer 1

+1 A:

I think I'd just push a dummy point on the beginning of your points vector, and leave the point references 1-based. I'd also get rid of the while (!in.eof()), which will normally read the last line twice. Finally, I'd use a few overloads of operator>> to read most of the data, giving a result that looked something like this:

#include <locale>
#include <vector>
#include <sstream>
#include <string>
#include <fstream>

/* change to "#if 0" for normal compilation: */
#if 1
struct Triangle { float a, an, atc, b, bn, btc, c, cn, ctc; };
struct Vector2d { float x, y; };
struct Vector3d { float x, y, z; };

std::vector<Triangle> triangles;
std::vector<Vector3d> points, normals;
std::vector<Vector2d> texcords;
#endif

namespace { 
struct slashsep: std::ctype<char> {
    slashsep(): std::ctype<char>(get_table()) {}

    static std::ctype_base::mask const* get_table() {
        static std::vector<std::ctype_base::mask> 
            rc(std::ctype<char>::table_size,std::ctype_base::mask());

        rc['/'] = std::ctype_base::space; // Treat '/' as a separator between numbers.
        rc[' '] = std::ctype_base::space;
        rc['\n'] = std::ctype_base::space;
        rc['\t'] = std::ctype_base::space;
        return &rc[0];
    }
};

std::istream &operator>>(std::istream &in, Triangle &triangle) { 
    std::string str;

    std::getline(in, str);
    std::istringstream temp(str);
    slashsep loc;
    temp.imbue(std::locale(std::locale(), &loc));

    temp >> triangle.a >> triangle.an >> triangle.atc;
    temp >> triangle.b >> triangle.bn >> triangle.btc;
    temp >> triangle.c >> triangle.cn >> triangle.ctc;
    return in;
}

std::istream &operator>>(std::istream &in, Vector3d &v) { 
    return in >> v.x >> v.y >> v.z;
}

std::istream &operator>>(std::istream &in, Vector2d &v) { 
    return in >> v.x >> v.y;
}
}

bool read_obj(std::string const &fileName) { 
    points.clear();
    points.push_back(Vector3d());
    triangles.clear();

    std::ifstream in(fileName.c_str());
    std::string cmd;

    if (!in.is_open())
        return false;

    while(in>>cmd) {
        if(cmd=="v") {
            Vector3d vector;
            in >> vector;
            points.push_back(vector);
        }
        if(cmd=="vt") {
            Vector2d texcord;
            in >> texcord;
            texcords.push_back(texcord);
        }
        if(cmd=="vn"){
            Vector3d normal;
            in >> normal;
            normals.push_back(normal);
        }
        if(cmd=="f") {
            Triangle triangle;
            in >> triangle;
            triangles.push_back(triangle);
        }
    }
    return true;
}

One minor point: while using the locale to treat '/' as a separator between numbers works for the specific variant of OBJ that you're looking at, it will not work for files that contain lines like:

f a//b c//d e//f

Nonetheless, the general idea (most reading with operator>>) will be fine when/if you decide to enhance it to handle this variant of the format.

Edit: I think I just realized part of the problem. The code to read a face should be like this:

temp >> triangle.a >> triangle.atc >> triangle.an;
temp >> triangle.b >> triangle.btc >> triangle.bn;
temp >> triangle.c >> triangle.ctc >> triangle.cn;

I.e., in the file, it's arranged as vertex/texcoord/normal, but your code and my previous version above tried to read it as vertex/normal/texcoord). Once the code was arranged this way, checking against a reference made the problem fairly obvious.

Jerry Coffin 2010-05-25 23:16:40

Thx :) But when I compile this code I get error in free.c ( some file that compiler include), I compiling with vs 2008, mayby this is problem. Error : Windows has triggered a breakpoint in Project.exe.This may be due to a corruption of the heap, which indicates a bug in Project.exe or any of the DLLs it has loaded.This may also be due to the user pressing F12 while Project.exe has focus.The output window may have more diagnostic information.

subSeven 2010-05-25 23:43:50

But, what about this skew ?:/ I don't know why it spread this way.

subSeven 2010-05-26 00:03:57

My guess is the incorrect placement is due to interpreting the texcoord as the normal and vice versa.

Jerry Coffin 2010-05-26 13:16:19

Answer 2

A:

Ok i fix all :D:D What I do: change

glTexCoord2f(tc.x,tc.y);

to

glTexCoord2f(tc.x,1-tc.y);

and the most important thing I change image resolution to 1024x1024 ( I useing mipmaping so I think correct image resolution is important) Now: Can sameone explain me why lTexCoord2f(tc.x,1-tc.y); work ? and is it important to make every image 2^x resolution ?

subSeven 2010-05-27 15:28:02

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Opengl problem with texture in model from obj

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