Displaying 3D points in OpenGL by reading in textfile - c++

Question

I am trying to plot 3D points by reading in a series of coordinates contained in a text file but I don't seem to get any output.
I personally think that either I am doing something wrong while reading my text file or in void reshape
Here is my code so far:
#include <glut.h>
#include <iostream>
#include <fstream>
#include <sstream>
using namespace std;
struct POINTS
{
int n;
float x;
float y;
float z;
};
POINTS point[1371];
void initGL()
{
glClearColor(0.0, 0.0, 0.0, 0.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glOrtho(-200, 0.0, 0.0, 200, 0.0, 300);
}
void display()
{
ifstream f;
f.open("points.txt");
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glPointSize(2);
glBegin(GL_POINTS);
for (int i = 0; i < 1371; ++i)
{
f >> point[i].n >> point[i].x >> point[i].y >> point[i].z;
cout << point[i].n << " " << point[i].x << " " << point[i].y << " " << point[i].z << endl;
glVertex3f(point[i].x, point[i].y, point[i].z);
}
glEnd();
glFlush();
f.close();
glutSwapBuffers();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei)w, (GLsizei)h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(65.0, (GLfloat)w / (GLfloat)h, 1.0, 20.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(-117.564, 36.7301, -5.0, -117.564, 36.7301, 151.769, 0, 1, 0);
}
int main(int argc, char* argv[])
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA
| GLUT_SINGLE | GLUT_MULTISAMPLE); // initialize GLUT
glutInitWindowSize(640, 480); // set the window size
glutInitWindowPosition(100, 100); // set display-window width and height to 100
glutCreateWindow("Plotting a series of 3D Points");
glutReshapeFunc(reshape);
glutDisplayFunc(display); // send graphics to display window
initGL();
glutMainLoop();
return 0;
}
And here is the text file:
0 -117.6027 161.5286 70.5128
1 -82.9727 87.7585 107.0592
2 -117.6027 72.2113 106.0432
3 -92.2141 80.0949 116.0134
4 -86.2138 96.987 122.6796
5 -102.6702 75.0957 108.7022
6 -58.8401 129.0492 72.169
7 -75.3688 91.5178 93.905
8 -97.0844 22.4057 115.8543
9 -101.1874 18.6077 127.3053
10 -111.0116 13.8925 122.3735

Answer 1

Your points are clipped by the near an far plane of the Viewing frustum of the perspective projection. Alle the geometry which is not in between the near and far plane is clipped:
Increase the distance between the near and far plane (gluPerspective) and change the look at (gluLookAt) the scene:
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(65.0, (GLfloat)w / (GLfloat)h, 1.0, 200.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(-117.564, 36.7301, -1.0, -117.564, 36.7301, 0.0, 0, 1, 0);