Pointer

fReqZz · #1 (**permalink**) March 23rd, 2007, 09:59 AM

I got a problem using pointer.

I got two table in two different file.

First one:

x y z

7 6 5
1 3 4
2 1 4

the other one:

node1 node2 node3

1 2 3
2 3 1
3 1 2

My problem is, how do i point table two to take the value of table one.

let say table two says node1 = 1, node2 = 2 and node3 = 3
so the out put will be:

(7,6,5)(1,3,4)(2,1,4)

it means that the number in table two will refer to line in table one.

Thanx.

Note: I have posted in many forum, but still no solution. I hope I can get some help here.

fReqZz · #2 (**permalink**) March 25th, 2007, 11:38 PM

Please someone help me on this one!

Geo121 · #3 (**permalink**) March 26th, 2007, 06:22 AM

As far as I can tell the function you are trying to get your program to perform doesn't require pointers and the output description is a little hazy, I think I understand what you are trying to do but it would be better if you used a better description and just a hint you will never get any help by asking how to do it you must post the code you have tryed and ask what you are doing wrong

~ Geo

~ Don't take life too seriously, you'll never get out alive!

fReqZz · #4 (**permalink**) March 27th, 2007, 01:02 AM

Ok. I did this.

Code:

#include <iostream.h>
#include <vector>
#include <fstream.h>

using namespace std;

struct Point
{
    double x,y,z;

};    

struct Tin
{
    int node1, node2, node3;    


};

istream & operator >> (istream & in, Point & pt)
{
    in >> pt.x >> pt.y >> pt.z;

    return in;
}

ostream & operator << (ostream & out , const Point & pt)
{
    out << "(" << pt.x <<","<<  pt.y << "," << pt.z << ")" ;

    return out;
}

Point *ReadVertexFile (char *filename, int &vertexArraySize)
{
    ifstream in (filename, ios::in);


    if (!in.is_open())
    {
    return NULL;
    }

    in >> vertexArraySize;

    Point *vertexArray = new Point[vertexArraySize];

    if (vertexArray == NULL)
    {
        return NULL;
    }

    int index = 0;

    while (in >> vertexArray[index])
    {
        index ++;
    }

    return vertexArray;
}

Tin *ReadTinFile(char *filename, int &TinArraySize)
{
    ifstream in (filename, ios::in);

    if (!in.is_open())
    {
        return NULL;
    }

    in >> TinArraySize;

    Tin *TinArray = new Tin[TinArraySize];

    if (TinArray == NULL)
    {
        return NULL;
    }

    int index = 0;

    while (in >> TinArray[index].node1 >> TinArray[index].node2 >> TinArray[index].node3)
    {
        index ++;
    }

    return TinArray;
}

int main()
{
    int TinArraySize;
    int VertexArraySize;

    Point *vertexArray = ReadVertexFile("lochass.txt", VertexArraySize);
    Tin *TinArray = ReadTinFile("lochas.txt", TinArraySize);

    for ( int i = 0; i < TinArraySize; i++)
    {

        Point vertexA = vertexArray[ TinArray[i].node1 ];
        Point vertexB = vertexArray[ TinArray[i].node2 ];
        Point vertexC = vertexArray[ TinArray[i].node3 ];

        cout << vertexA << "," << vertexB << "," << vertexC << endl;
    }

    return 0;
}

However, one problem. When i wanted to plot the vertex line, it became a problem. OpenGL needs 3 parameter while i have only one for each three coordinates which is vertexA, vertexB and vertexC.

So how could I break those so i can plot it with something like this:

Code:

glVertex3f(node1.x[1],node1.y[1],node1.z[1])
glVertex3f(node2.x[1],node2.y[1],node2.z[1])
glVertex3f(node3.x[1],node3.y[1],node3.z[1])

Thanks.

Peter_APIIT · #5 (**permalink**) May 20th, 2007, 04:09 AM

I don't understand this program. why you never specified the function prototype and
don't add .h behind the header file instead of this <iostream>

The <iostream.h> and <iostream.h is totally different
because the <iostream> is packed in a std namespace.

The newer compiler will complaint this mistake.

Please coding in stadard C++ in order to enhance portable.

I hope this help.

Linux is the best OS in the world.

rick84 · #6 (**permalink**) June 5th, 2007, 01:09 AM

in opengl the is a corresponding fucntion glVertex3fv which takes a
pointer to an array where u have stored ur x,y,z co-ordinates.
try using it here's an example
int vert[] = {1,1,1};
glVertex3iv(vert);
in case of float just replace i by f in glVertex*v;