OpenGL + Triangulation

[freqzz]

 
#include <windows.h> 
#include <gl\gl.h>
#include <gl\glut.h>
#include <stdlib.h>
#include <math.h>
#include <vector>
#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
 
 
 
struct Point3D
{
    float x, y, z;
};
 
struct Triangle
{
    char name[10];
    Point3D point[3];
};
 
istream & operator >> (istream & in , Point3D & pt)
{
    char c;
 
    in >> c >> pt.x >> c >> pt.y >> c >> pt.z >> c;
 
    return in;
}
 
istream & operator >> (istream & in, Triangle & tri)
{
    in >> tri.name >> tri.point[0] >> tri.point[1] >> tri.point[2];
 
    return in;
}
 
ostream & operator << (ostream & out , const Point3D & pt)
{
    out << "(" << pt.x << "," << pt.y << "," << pt.z << ")";
 
    return out;
}
 
ostream & operator << (ostream & out , const Triangle & tri)
{
    out << tri.name << " " << tri.point[0] << " " << tri.point[1] << " " << tri.point[2];
 
    return out;
}
 
float read () 
{
 
    std::vector<Triangle> v;
 
    ifstream in ("sample.txt", ios::in);
 
    if (!in)
 
    {
        cout << "could not open" << endl;
        return 1;
    }
 
    return 1;
}
 
void draw (const Triangle)
{
    Triangle triangle;
 
    while (in >> triangle)
    {
        v.push_back(triangle);
    }
 
    glBegin(GL_TRIANGLES);
 
    for (int i = 0, i<v.size(), i++)
    {
        glVertex3f(v[i]);
    }
 
    glEnd;
 
    glutSwapBuffers();
 
    return 0;
 
}
 
int main (int argc, char **argv) 
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); 
    glutInitWindowSize(640, 480);  
    glutInitWindowPosition(10,10); 
    glutCreateWindow("Triangle"); 
    //init(); 
    glMatrixMode(GL_PROJECTION);
    glutDisplayFunc(draw);
    //glutKeyboardFunc(keyboard);
 
    glutMainLoop ();
 
    return 0;
 
}
 
 

How do I pass the value from the read( ) into draw ( ) so I can retain the x,y,z value. So I can draw the point into triangle.

This is ther first time I combine both graphic programming and OO. So, explaination will be helpful.

[horace1]

not sure what you wish to do? I assume some form of animation - have you seen the spinning triangle example?
http://www.lighthouse3d.com/opengl/glut/index.php?4

[freqzz]

This is part of code where I want to read a Triangle table from textfile and plot it to draw a triangle. From there, i would like to texture the triangle and build a camera movement.

But now, i'm stuck at the point where a i couldnt pass the x,y,z valu for drawing.

[horace1]

This is part of code where I want to read a Triangle table from textfile and plot it to draw a triangle. From there, i would like to texture the triangle and build a camera movement.

But now, i'm stuck at the point where a i couldnt pass the x,y,z valu for drawing.

some initial ideas - not sure if it is what you required - but it compiles and starts to run

 
//  ** read trianges into vector v
std::vector<Triangle> v;  // moved - make global for now????
 
float read () 
{
 
    //std::vector<Triangle> v;   
 
    ifstream in ("sample.txt", ios::in);
 
    if (!in)
 
    {
        cout << "could not open" << endl;
        return 1;
    }
    Triangle triangle;   // **** moved to here
 
    while (in >> triangle)
    {
        v.push_back(triangle);
    }
 
    return 1;
}
 
void draw ()  // ** removed const Triangle)
{
 
    glBegin(GL_TRIANGLES);
 
    for (int i = 0; i<v.size(); i++)  // ** replaced , with ;
    {
        glVertex3f(v[i].point[0].x, v[i].point[0].y, v[i].point[0].z);   //  pass first vertex
        //  <<<  call glVertex3f() to pass other two vertexs here
    }
 
    glEnd();
 
    glutSwapBuffers();
 
    return;
 
}
 
int main (int argc, char **argv) 
{
    read();  // ** read triangles
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); 
    glutInitWindowSize(640, 480);  
    glutInitWindowPosition(10,10); 
    glutCreateWindow("Triangle"); 
    //init(); 
    glMatrixMode(GL_PROJECTION);
    glutDisplayFunc(draw);
    //glutKeyboardFunc(keyboard);
 
    glutMainLoop ();
 
    return 0;
 
}
 

read() reads the triangle data into vector v - call it from main() make v global

draw() can then read the vertex data from v

does that help?

[freqzz]

Thanks. It does help a bit. I'll modify 2-3 things before posting the code back. I'll keep this updated.

[freqzz]

I have finish created a fully fuctioniol OpenGL program with some camera movement. Now how do I texture the triangle?

 
 
#include <windows.h> 
#include <gl\gl.h>
#include <gl\glut.h>
#include <stdlib.h>
#include <math.h>
#include <vector>
#include <iostream.h>
#include <fstream.h>
#include <stdio.h>
 
float zoom = 15.0f;
float rotx = 0;
float roty = 0.001f;
float tx = 0;
float ty = 0;
int lastx=0;
int lasty=0;
unsigned char Buttons[3] = {0};
 
struct Point3D
{
    float x, y, z;
};
 
struct Triangle
{
    char name[10];
    Point3D point[3];
};
 
istream & operator >> (istream & in , Point3D & pt)
{
    char c;
 
    in >> c >> pt.x >> c >> pt.y >> c >> pt.z >> c;
 
    return in;
}
 
istream & operator >> (istream & in, Triangle & tri)
{
    in >> tri.name >> tri.point[0] >> tri.point[1] >> tri.point[2];
 
    return in;
}
 
ostream & operator << (ostream & out , const Point3D & pt)
{
    out << "(" << pt.x << "," << pt.y << "," << pt.z << ")";
 
    return out;
}
 
ostream & operator << (ostream & out , const Triangle & tri)
{
    out << tri.name << " " << tri.point[0] << " " << tri.point[1] << " " << tri.point[2];
 
    return out;
}
 
std::vector<Triangle> v;
 
float read () 
{
 
    //std::vector<Triangle> v;
 
    ifstream in ("sample.txt", ios::in);
 
    if (!in)
 
    {
        cout << "could not open" << endl;
        return 1;
    }
 
    Triangle triangle;
 
    while (in >> triangle)
    {
        v.push_back(triangle);
    }
 
    return 1;
 
}
 
void init()
{
    //glEnable(GL_DEPTH_TEST);
    //glClearColor(0.0,0.0,0.0,0.0);
    //glColor3f(1.0, 1.0, 1.0);
    glLoadIdentity();
    //glOrtho(-10,10,-10,10,-10,10);
 
}
 
 
void draw ()
{
 
    glClear(GL_COLOR_BUFFER_BIT);
 
    glLoadIdentity();
 
    glTranslatef(0,0,-zoom);
    glTranslatef(tx,ty,0);
    glRotatef(rotx,1,0,0);
    glRotatef(roty,0,1,0);    
 
 
    glBegin(GL_TRIANGLES); // I would like to texture this
                                               // combination of multiple triangle
 
    for ( int i = 0; i<v.size(); ++i)
    {
        glVertex3f(v[i].point[0].x, v[i].point[0].y, v[i].point[0].z);
        glVertex3f(v[i].point[1].x, v[i].point[1].y, v[i].point[1].z);
        glVertex3f(v[i].point[2].x, v[i].point[2].y, v[i].point[2].z);
 
    }    
 
    glEnd();
 
    glutSwapBuffers();
 
    glBegin(GL_LINES);
    for(int j=-10;j<=10;++j) 
    {
        glVertex3f(j,0,-10);
        glVertex3f(j,0,10);
 
        glVertex3f(10,0,j);
        glVertex3f(-10,0,j);
    }
 
    glEnd();
 
    glutSwapBuffers();
}
 
void reshape(int w, int h)
{
 
    if(w==0) 
        h = 1;
 
    glViewport(0,0,w,h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(100,(float)w/h,1,100);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
}
 
void Motion(int x,int y)
{
    int diffx=x-lastx;
    int diffy=y-lasty;
    lastx=x;
    lasty=y;
 
    if( Buttons[0] && Buttons[1] )
    {
        zoom -= (float) 0.05f * diffx;
    }
    else
        if( Buttons[0] )
        {
            rotx += (float) 0.5f * diffy;
            roty += (float) 0.5f * diffx;        
        }
        else
            if( Buttons[1] )
            {
                tx += (float) 0.05f * diffx;
                ty -= (float) 0.05f * diffy;
            }
            glutPostRedisplay();
}
 
void Mouse(int b,int s,int x,int y)
{
    lastx=x;
    lasty=y;
    switch(b)
    {
    case GLUT_LEFT_BUTTON:
        Buttons[0] = ((GLUT_DOWN==s)?1:0);
        break;
    case GLUT_MIDDLE_BUTTON:
        Buttons[1] = ((GLUT_DOWN==s)?1:0);
        break;
    case GLUT_RIGHT_BUTTON:
        Buttons[2] = ((GLUT_DOWN==s)?1:0);
        break;
    default:
        break;        
    }
    glutPostRedisplay();
}
 
int main (int argc, char **argv) 
{
    read();
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB); 
    glutInitWindowSize(640, 480);  
    glutInitWindowPosition(10,10); 
    glutCreateWindow("Triangle"); 
 
    init(); 
    glMatrixMode(GL_PROJECTION);
 
    glutDisplayFunc(draw);
    glutReshapeFunc(reshape);
    glutMouseFunc(Mouse);
    glutMotionFunc(Motion);
 
    glutMainLoop ();
 
    return 0;
 
}
 
 

Any help will be highly appreciated.

[horace1]

have you seen this example in the codeproject?
http://www.codeproject.com/opengl/openglstruct.asp

[freqzz]

have you seen this example in the codeproject?
http://www.codeproject.com/opengl/openglstruct.asp

That does not even come close to my requirement. But thanks. I just want to wrap a combination of Triangle.

[freqzz]

Any help? I'm practically stuck here..