Viewing 3D objects in 2D coordinate

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-1

I have the following C++ code to generate an ellipsoid in 3D I tried to view the object but the ellipsoid was too small and looks like a line !!

#include <iostream>
#include <GL/freeglut.h>
#include <math.h>

using namespace std;

GLfloat Rx = 100, Ry = 100, Rz = 100;
GLfloat ellipsoid[360][18][3];

void GenerateEllipsoid() {
for (int i = 0; i < 360; i++) {
    GLfloat theta = (i - 180.0) * 22.0 / (7.0 * 180.0);
    for (int j = 0; j < 18; j++) {
        GLfloat phi = (j * 10 - 90) * 22.0 / (7.0 * 180.0);
        ellipsoid[i][j][0] = Rx * cos(phi) * cos(theta);
        ellipsoid[i][j][1] = Ry * cos(phi) * cos(theta);
        ellipsoid[i][j][2] = Rx * sin(phi);
    }
  }
}

void TransformFor3DViewing() {
GLfloat x0 = 50, y0 = 50, z0 = 100;

GLfloat xref = ellipsoid[0][0][0], yref = ellipsoid[0][0][1], zref = ellipsoid[0][0][2];
GLfloat length_N = sqrt(pow(x0 - xref, 2) + pow(y0 - yref, 2) + pow(z0 - zref, 2));
GLfloat nx = (x0 - xref) / length_N, ny = (y0 - yref) / length_N, nz = (z0 - zref) / length_N;

GLfloat ux = nz, uy = 0, uz = -nx;

GLfloat vx = -ny * nx, vy = nz * nz + nx * nx, vz = -ny * nz;

for (int i = 0; i < 360; i++) {
    for (int j = 0; j < 18; j++) {
        ellipsoid[i][j][0] -= x0;
        ellipsoid[i][j][1] -= y0;
        ellipsoid[i][j][2] -= z0;
    }
}
for (int i = 0; i < 360; i++) {
    for (int j = 0; j < 18; j++) {
        ellipsoid[i][j][0] = ellipsoid[i][j][0] * ux + ellipsoid[i][j][1] * uy + ellipsoid[i][j][2] * uz;
        ellipsoid[i][j][1] = ellipsoid[i][j][0] * vx + ellipsoid[i][j][1] * vy + ellipsoid[i][j][2] * vz;
        ellipsoid[i][j][2] = ellipsoid[i][j][0] * nx + ellipsoid[i][j][1] * ny + ellipsoid[i][j][2] * nz;
    }
}

GLfloat zvp = 0;
GLfloat xprp = x0, yprp = y0, zprp = z0;

for (int i = 0; i < 360; i++) {
    for (int j = 0; j < 18; j++) {
        ellipsoid[i][j][0] = ellipsoid[i][j][0] * ((zprp - zvp) / (zprp - ellipsoid[i][j][2])) +
                            xprp * ((zvp - ellipsoid[i][j][2]) / (zprp - ellipsoid[i][j][2]));
        ellipsoid[i][j][1] = ellipsoid[i][j][1] * ((zprp - zvp) / (zprp - ellipsoid[i][j][2])) +
                            yprp * ((zvp - ellipsoid[i][j][2]) / (zprp - ellipsoid[i][j][2]));
    }
}
}

void myDisplay() {
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_POINTS);
    for (int i = 0; i < 360; i++)
    {
            for (int j = 0; j < 18; j++)
       {
           glVertex2f(ellipsoid[i][j][0], ellipsoid[i][j][1]);
       }
    }
    glEnd();
    glFlush();
 }

int main(int argc, char **argv) {
    glutInit(&argc, argv);
    glutInitWindowSize(800, 600);
    glutInitWindowPosition(0, 0);
    glutCreateWindow("Ellipsoid Viewing");
    glClearColor(1, 1, 1, 0.0);
    glColor3f(0.0f, 0.0f, 0.0f);
    gluOrtho2D(-400, 400, -300, 300);
    GenerateEllipsoid();
    TransformFor3DViewing();
    glutDisplayFunc(myDisplay);
    glutMainLoop();
}

I need the following add a function TransformFor2DViewing to view the ellipsoid in 2D change the viewing point by mouse clicks

any help ??

edited 12 secs ago

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asked 1 min ago

user3212556

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