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OpenGL OBJ in OpenGl

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OBJ files are just text files. I suggest you to export something simple from blender (a cube, a sphere) and read the .obj file with a text editor. It is very easy to understand what's saved there, once you get it, it will be super easy to parse the file and import it into your engine structure.

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Actually I would recommend getting a free .obj model from turbosquid.com and trying to load that. Something as complex as possible. There are things you would need to account for with .obj files that you might not get with a simple model you made from Blender.

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i am really new to all that ! , so that way i am looking for example !! , i look inside and try a simple one before but i cant load it there is a loot of thinks that i dont understand in the structure
if you have a example to load the obj that will help .

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i am really new to all that ! , so that way i am looking for example !! , i look inside and try a simple one before but i cant load it there is a loot of thinks that i dont understand in the structure
if you have a example to load the obj that will help .


I'm using OBJ files right now because they are easy to load and easy to edit. However, they suck. I have one file that contains 4800 faces. It takes more than a minute to load. Human readable formats really are not the way to go for a game. Not only do they take obscenely long to load, but they allow for anyone to edit them with nothing more than a text editor.

An OBJ file can store a 3D model and not much more. They are extremely limited. They contain (typically) nothing more than vertex, normal, uv and face data and possibly material data. You'll find the material data even less useful since you'll have to edit the OBJ file to put the correct path in to the material file(s). You mention ALL of the OBJ file's features. There are many, most undocumented, and even fewer have made it into an importer/exporter. Fewer still have much use in a game. So, with that being said, why are you so stuck on using OBJ files?

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I understand that this is going to be computer specific...but 4800 faces taking over a minute? What exactly is your OBJ loader doing? My loader (on my machine) is doing 100k vertexs/normals/texcoords or ~33k faces, including a rather bastardized type of triangulation, in roughly 7 seconds. Of course I'm not generating normals on models that don't have them but that would hardly account for an additional minute or processing time...

Did you write yours in python MarkS?

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I understand that this is going to be computer specific...but 4800 faces taking over a minute? What exactly is your OBJ loader doing? My loader (on my machine) is doing 100k vertexs/normals/texcoords or ~33k faces, including a rather bastardized type of triangulation, in roughly 7 seconds. Of course I'm not generating normals on models that don't have them but that would hardly account for an additional minute or processing time...

Did you write yours in python MarkS?


unsure.gif No Python! I wrote the loader using std::vector and that seemed to affect the loading times, but it was worth it since I don't have to make multiple passes through the file to count vertices and faces and it greatly simplified the code. Still, converting the same OBJ file to a binary format and reading the data directly into a data structure was orders of magnitude faster.

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[quote name='Ahl' timestamp='1323995351' post='4894342']
I understand that this is going to be computer specific...but 4800 faces taking over a minute? What exactly is your OBJ loader doing? My loader (on my machine) is doing 100k vertexs/normals/texcoords or ~33k faces, including a rather bastardized type of triangulation, in roughly 7 seconds. Of course I'm not generating normals on models that don't have them but that would hardly account for an additional minute or processing time...

Did you write yours in python MarkS?


unsure.gif No Python! I wrote the loader using std::vector and that seemed to affect the loading times, but it was worth it since I don't have to make multiple passes through the file to count vertices and faces and it greatly simplified the code. Still, converting the same OBJ file to a binary format and reading the data directly into a data structure was orders of magnitude faster.
[/quote]

I did my original OBJ loader in Python and there was a tremendous speed difference between that and my C++ re-write, hence my question. I'm presently using std::vectors and even with not pre-counting my vertexs, texcoords, normals, etc. and just push_bach()'ing everything it isn't that slow.

What kind of data structure are you reading your info into? You've peaked my curiosity.

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What kind of data structure are you reading your info into? You've peaked my curiosity.


I'll do one better. Here is the code. It isn't the best, but it worked for my purpose. I've transitioned my models to a custom, binary format. I'm still using the old stdio functions and had planned to convert this to the newer C++ functions, but it really is a moot point now.

OBJ Loader.h
[source]

#ifndef __OBJ_LOADER__
#define __OBJ_LOADER__

#include <vector>
#include <string>

using namespace std;

class OBJ_vertex{
public:
OBJ_vertex(){}
~OBJ_vertex(){}

float GetX() const {return(x);}
void SetX(float _x) {x = _x;}

float GetY() const {return(y);}
void SetY(float _y) {y = _y;}

float GetZ() const {return(z);}
void SetZ(float _z) {z = _z;}

private:
float x;
float y;
float z;
};

class uv_coords{
public:
uv_coords(){}
~uv_coords(){}

float GetU() const {return(u);}
void SetU(float _u) {u = _u;}

float GetV() const {return(v);}
void SetV(float _v) {v = _v;}

private:
float u;
float v;
};

class face{
public:
face();
face(const face &right);
~face();

long GetNumVertices() const;
long GetNumNormals() const;
long GetNumUVs() const;

void AddVertex(long index);
long GetVertex(long index) const;

void AddNormal(long index);
long GetNormal(long index) const;

void AddUV(long index);
long GetUV(long index) const;

private:
vector<long> *vertices;
vector<long> *normals;
vector<long> *uv;
};

class OBJ{
public:
OBJ();
~OBJ();

long GetNumVertices() const;
long GetNumNormals() const;
long GetNumUVs() const;
long GetNumFaces() const;

OBJ_vertex *GetVertex(long index) const;
OBJ_vertex *GetNormal(long index) const;
uv_coords *GetUV(long index) const;
face *GetFace(long index) const;

void LoadOBJ(string file_name);
void DumpOBJ(void);

private:
vector<OBJ_vertex> *vertices;
vector<OBJ_vertex> *normals;
vector<uv_coords> *uv;
vector<face> *faces;
};

#endif
[/source]

OBJ Loader.cpp
[source]

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "OBJ Loader.h"

face::face()
{
vertices = new vector<long>;
normals = new vector<long>;
uv = new vector<long>;
}

face::face(const face &right)
{
long i;

vertices = new vector<long>;
normals = new vector<long>;
uv = new vector<long>;

for(i = 0;i < right.vertices->size();i++)
vertices->push_back(right.vertices->at(i));
for(i = 0;i < right.normals->size();i++)
normals->push_back(right.normals->at(i));
for(i = 0;i < right.uv->size();i++)
uv->push_back(right.uv->at(i));
}

face::~face()
{
delete vertices;
vertices = NULL;

delete normals;
normals = NULL;

delete uv;
uv = NULL;
}

long face::GetNumVertices() const
{
return(vertices->size());
}

long face::GetNumNormals() const
{
return(normals->size());
}

long face::GetNumUVs() const
{
return(uv->size());
}

void face::AddVertex(long index)
{
vertices->push_back(index);
}

long face::GetVertex(long index) const
{
if(index < 0 || index > vertices->size() - 1)
return(NULL);

return(vertices->at(index));
}

void face::AddNormal(long index)
{
normals->push_back(index);
}

long face::GetNormal(long index) const
{
if(index < 0 || index > normals->size() - 1)
return(NULL);

return(normals->at(index));
}

void face::AddUV(long index)
{
uv->push_back(index);
}

long face::GetUV(long index) const
{
if(index < 0 || index > uv->size() - 1)
return(NULL);

return(uv->at(index));
}

OBJ::OBJ()
{
vertices = new vector<OBJ_vertex>;
normals = new vector<OBJ_vertex>;
uv = new vector<uv_coords>;
faces = new vector<face>;
}

OBJ::~OBJ()
{
delete vertices;
vertices = NULL;

delete normals;
normals = NULL;

delete uv;
uv = NULL;

delete faces;
faces = NULL;
}

long OBJ::GetNumVertices() const
{
return(vertices->size());
}

long OBJ::GetNumNormals() const
{
return(normals->size());
}

long OBJ::GetNumUVs() const
{
return(uv->size());
}

long OBJ::GetNumFaces() const
{
return(faces->size());
}

OBJ_vertex *OBJ::GetVertex(long index) const
{
if(index < 0 || index > vertices->size() - 1)
return(NULL);

return(&vertices->at(index));
}

OBJ_vertex *OBJ::GetNormal(long index) const
{
if(index < 0 || index > normals->size() - 1)
return(NULL);

return(&normals->at(index));
}

uv_coords *OBJ::GetUV(long index) const
{
if(index < 0 || index > uv->size() - 1)
return(NULL);

return(&uv->at(index));
}

face *OBJ::GetFace(long index) const
{
if(index < 0 || index > faces->size() - 1)
return(NULL);

return(&faces->at(index));
}

void OBJ::LoadOBJ(string file_name)
{
FILE *fs;
char c;
bool done,has_normals,has_uvs;
OBJ_vertex vert;
uv_coords uvs;
face *temp_face;
float x,y,z;
float u,v;
int vert_ind,norm_ind,uv_ind;
int read_count;

if(fopen_s(&fs,file_name.c_str(),"r") != 0)
return;

done = false;
has_normals = false;
has_uvs = false;

while(!done)
{
switch(fgetc(fs))
{
case '#': // Comment. Fall through
case 'u': // Fall through
case 's': // Fall through
case 'g': // Group. Not supported. Fall through
while(fgetc(fs) != '\n'); // Skip to the next line
break;
case EOF: // End of file reached. We be done.
done = true;
break;
case 'v': // Loading vertices is easy. Faces, not so much...
switch(fgetc(fs))// The next character determines what type of vertex we are loading
{
case ' ': // Loading vertices
fscanf_s(fs,"%f %f %f\n",&x,&y,&z);
vert.SetX(x);
vert.SetY(y);
vert.SetZ(z);
vertices->push_back(vert);
break;
case 'n': // Loading normals
has_normals = true;
fscanf_s(fs,"%f %f %f\n",&x,&y,&z);
vert.SetX(x);
vert.SetY(y);
vert.SetZ(z);
normals->push_back(vert);
break;
case 't': // Loading UVs
has_uvs = true;
fscanf_s(fs,"%f %f\n",&u,&v);
uvs.SetU(u);
uvs.SetV(v);
uv->push_back(uvs);
break;
default: // Uh oh... What are we trying to read here? Someone screwed up their OBJ exporter...
cout << "Invalid vertex type: " << "v" << c << " Should be of type \"v \", \"vn\" or \"vt\"." << endl;
return;
}
break;
case 'f':
if(has_normals && has_uvs)
{
temp_face = new face;
while(fgetc(fs) != '\n')
{
vert_ind = 0;
norm_ind = 0;
uv_ind = 0;

read_count = fscanf_s(fs,"%d/%d/%d",&vert_ind,&uv_ind,&norm_ind);
if((read_count != 3) || (vert_ind == 0) || (uv_ind == 0) || (norm_ind == 0)) // Valid indices start at 1 in a .OBJ file. Don't know why... O.o
{
delete temp_face;
temp_face = NULL;

cout << "Invalid vertex index." << endl;
return;
}

temp_face->AddVertex(vert_ind - 1); // We want the indices to start at 0, so subtract 1.
temp_face->AddNormal(norm_ind - 1);
temp_face->AddUV(uv_ind - 1);
}
faces->push_back(*temp_face);

delete temp_face;
temp_face = NULL;
}else if(has_normals && !has_uvs){
temp_face = new face;
while(fgetc(fs) != '\n')
{
vert_ind = 0;
norm_ind = 0;

read_count = fscanf_s(fs,"%d//%d",&vert_ind,&norm_ind);
if((read_count != 2) || (vert_ind == 0) || (norm_ind == 0))
{
delete temp_face;
temp_face = NULL;

cout << "Invalid vertex index." << endl;
return;
}

temp_face->AddVertex(vert_ind - 1);
temp_face->AddNormal(norm_ind - 1);
temp_face->AddUV(0);
}
faces->push_back(*temp_face);

delete temp_face;
temp_face = NULL;
}else if(!has_normals && has_uvs){
temp_face = new face;
while(fgetc(fs) != '\n')
{
vert_ind = 0;
uv_ind = 0;

read_count = fscanf_s(fs,"%d/%d/",&vert_ind,&uv_ind);
if((read_count != 2) || (vert_ind == 0) || (uv_ind == 0))
{
delete temp_face;
temp_face = NULL;

cout << "Invalid vertex index." << endl;
return;
}

temp_face->AddVertex(vert_ind - 1);
temp_face->AddNormal(0);
temp_face->AddUV(uv_ind - 1);
}
faces->push_back(*temp_face);

delete temp_face;
temp_face = NULL;
}else if(!has_normals && !has_uvs){
temp_face = new face;
while(fgetc(fs) != '\n')
{
vert_ind = 0;

read_count = fscanf_s(fs,"%d//",&vert_ind);
if((read_count != 1) || (vert_ind == 0))
{
delete temp_face;
temp_face = NULL;

cout << "Invalid vertex index." << endl;
return;
}

temp_face->AddVertex(vert_ind - 1);
temp_face->AddNormal(0);
temp_face->AddUV(0);
}
faces->push_back(*temp_face);

delete temp_face;
temp_face = NULL;
}
break;
}
}

fclose(fs);
}

void OBJ::DumpOBJ(void)
{
long i,j;

for(i = 0;i < GetNumVertices();i++)
cout << GetVertex(i)->GetX() << " " << GetVertex(i)->GetY() << " " << GetVertex(i)->GetZ() << endl;

for(i = 0;i < GetNumNormals();i++)
cout << GetNormal(i)->GetX() << " " << GetNormal(i)->GetY() << " " << GetNormal(i)->GetZ() << endl;

for(i = 0;i < GetNumUVs();i++)
cout << GetUV(i)->GetU() << " " << GetUV(i)->GetV() << endl;

for(i = 0;i < GetNumFaces();i++)
{
for(j = 0;j < GetFace(i)->GetNumVertices();j++)
cout << GetFace(i)->GetVertex(j) << "/" << GetFace(i)->GetUV(j) << "/" << GetFace(i)->GetNormal(j) << " ";
cout << endl;
}
}
[/source]

As you can tell, this will load a file even if it isn't formatted correctly. You can mix up the line order for the vertices and faces and it will still read correctly. Again, I needed a quick format to load. More advanced formats tend to require more advanced loaders and my models just were not that complex.

Also, I was just guessing with the "more than a minute" comment. I wasn't profiling this since it really wasn't that important. It *felt* like a long time.

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[quote name='Ahl' timestamp='1324068549' post='4894614']
What kind of data structure are you reading your info into? You've peaked my curiosity.


I'll do one better. Here is the code. It isn't the best, but it worked for my purpose. I've transitioned my models to a custom, binary format. I'm still using the old stdio functions and had planned to convert this to the newer C++ functions, but it really is a moot point now.

OBJ Loader.h
[source]
//Ta Codez!!!
[/source]

As you can tell, this will load a file even if it isn't formatted correctly. You can mix up the line order for the vertices and faces and it will still read correctly. Again, I needed a quick format to load. More advanced formats tend to require more advanced loaders and my models just were not that complex.

Also, I was just guessing with the "more than a minute" comment. I wasn't profiling this since it really wasn't that important. It *felt* like a long time.
[/quote]

Right on. I'm ashamed to post my code where others can see it. It's quite ugly....but it works. Getting it to work with every every model I can find has broken me of my insistence on coding everything myself from scratch. A good friend of mine calls it reinventing the wheel. Thank you .obj loader. You have taught me many lessons.

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