Load and Render *.obj file

Graphics and GPU Programming Programming OpenGL

Started by AMDFX April 27, 2011 08:54 PM

8 comments, last by AMDFX 12 years, 11 months ago

101

Author

April 27, 2011 08:54 PM

Hey!

I try to load and render an obj file with openGL 2.0 but it looks very buggy! I hope somebody can help me!

Source:

void LoadObjects() { 	ifstream obj; 	string obj_str; 	float Vektor[9999][3]; 	float x, y, z; 	int counter = 0; 	int i = 0; 	obj.open("box.obj", ios::in); 		while (!obj.eof()) 		{     		getline(obj, obj_str);     		size_t pos = obj_str.find("v  ");     		if (pos == 0) {         		sscanf(obj_str.c_str(), "v  %f %f %f", &x, &y, &z);         		Vektor[0] = x;         		Vektor[1] = y;         		Vektor[2] = z;         		i++;         		counter++;     		}; 		}; 		obj.close();          int j = 0; 		while (j <= counter) 		{     		glBegin(GL_TRIANGLES);         		j++;         		glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);         		j++;         		glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);         		j++;         		glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);     		glEnd();     		}; }

Picture is attachet! Sry for bad english but I hope you understand the Problem and can help me

szecs

2,990

April 28, 2011 05:58 AM

please repost the code somehow in a readable manner. Maybe with [ source ] tags.

[size=2]Portfolio [size=2]| Youtube channel | Paper modeller development blog | Journal

AMDFX

101

Author

April 28, 2011 06:07 AM

Oh ok...

void LoadObjects()
{
ifstream obj;
string obj_str;
float Vektor[9999][3];
float x, y, z;
int i = 0, j = 0;
obj.open("box.obj", ios::in);
while (!obj.eof())
{
getline(obj, obj_str);
size_t pos = obj_str.find("v ");
if (pos == 0) {
sscanf(obj_str.c_str(), "v %f %f %f", &x, &y, &z);
Vektor[0] = x;
Vektor[1] = y;
Vektor[2] = z;
i++;
};
};
obj.close();

while (j <= i)
{
glBegin(GL_POLYGON);
j++;
glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);
j++;
glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);
j++;
glVertex3f(Vektor[j][0], Vektor[j][1], Vektor[j][2]);
glEnd();
};
}

szecs

2,990

April 28, 2011 06:42 AM

Well, I suggest you to read up some documentation/tutorials on .obj loading, but maybe you miss some principles about graphics too. I guess you are new to openGL too, can you draw a simple cube for example? Not with glu functions.

[size=2]Portfolio [size=2]| Youtube channel | Paper modeller development blog | Journal

AMDFX

101

Author

April 28, 2011 06:55 AM

Yes I am new to OpenGL but I can draw a cube (without glu)

I update the code, looks maybe a little bit better:
void LoadObjects()
{
ifstream obj;
string obj_str;
float x, y, z, x1, y1, z1, x2, y2, z2;
int i = 0;
bool a, b;
obj.open("box.obj", ios::in);
while (!obj.eof())
{
getline(obj, obj_str);
size_t pos = obj_str.find("v ");
if (pos == 0) {
a = false; b = false;
if (i==0) {
sscanf(obj_str.c_str(), "v %f %f %f", &x, &y, &z);
i++;
a = true;
};
if (i==1 && !a) {
sscanf(obj_str.c_str(), "v %f %f %f", &x1, &y1, &z1);
i++;
b = true;
};
if (i==2 && !b)
sscanf(obj_str.c_str(), "v %f %f %f", &x2, &y2, &z2);
if (i == 2 && !a && !b) {
glBegin(GL_TRIANGLE_STRIP);
glVertex3f(x, y, z);
glVertex3f(x1, y1, z1);
glVertex3f(x2, y2, z2);
glEnd();
i = 0;
};
};
};
obj.close();
}

but same problem...

kdmiller3

178

April 28, 2011 07:45 AM

You may find the Wikipedia article on the Wavefront .obj file format helpful. The summary at FileFormat.Info is good too. In particular, check out the section on face definitions.

The simplest approach is to look up vertex positions, normals, and texture coordinates using the face indices and submit them to OpenGL. Be aware that faces can have more than three vertices so you might have to "unroll" them into several triangles.

AMDFX

101

Author

April 28, 2011 08:00 AM

Ah I understand know... I must use the "f " informations to connect the faces... I will try and report later

AMDFX

101

Author

April 28, 2011 08:01 AM

Ah I understand now... I must use the "f " informations to connect the faces... I will try and report later

Sollum

1,145

April 28, 2011 09:24 AM

Few days ago i was trying to make a loader myself, but then i thought that it might be better just to search for source codes on the net.

I found this one http://www.kixor.net/dev/objloader/

It basically gives you data structs to store obj info.

The only drawback that buzzes me a bit is that i have to know myself if model faces have more that 3 vertexes.

So i think it might make your life a bit easier.