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.lighthouse3 d.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.as p

[freqzz]

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

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..