OpenGL moving object doesn't work - c++

Question

I just want to do horizontally moving wheel. There's a code but it doesn't work - wheel just moving as a circle, leaving traces. I've tried to glTranslatef(0.0f, moveY, 0.0f); but it doesn't work too.
#include "stdafx.h"
#include <math.h>
#include <GL/freeglut.h>
#include <GL\GL.h>
#define window_width 1080
#define window_height 720
GLfloat angle; // wheel's rotator
GLfloat moveX; // wheel's mover by X
void DrawCircle(float cx, float cy, float r, int num_segments) {
glLoadIdentity();
glTranslatef(0, 0, -10); // set place where wheel starts to draw
glRotatef(angle, 0.0f, 0.0f, -0.1f); // rotate our wheel. it works correctly I think
glTranslatef(moveX, 0.0f, 0.0f); // but it makes me wonder. moving circle by X doesn't work
// part of a circle
glBegin(GL_TRIANGLE_FAN);
glColor3f(255, 255, 255);
for (int ii = 0; ii < num_segments; ii++) {
double twicePi = 2.0 * 3.142;
float theta = 2.0f * 3.1415926f * float(ii) / float(num_segments);
float x = r * cosf(theta);
float y = r * sinf(theta);
glVertex2f(x + cx, y + cy);
}
glEnd();
// second part of a circle
int i, x, y;
double radius = 1.20;
glColor3ub(0.0, 0.0, 0.0);
double twicePi = 2.0 * 3.142;
x = 0, y = 0;
glBegin(GL_TRIANGLE_FAN);
glVertex2f(x, y);
for (i = 0; i <= 20; i++) {
glVertex2f(
(x + (radius * cos(i * twicePi / 20))),
(y + (radius * sin(i * twicePi / 20)))
);
}
glEnd();
// there's an end of drawning of a circle
// this is where wheel starts to rotate and move
angle += 0.02f;
moveX += 0.00005f;
// there are spokes of a wheel
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(0.0, -1.2f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(0.0, 1.2f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.2f, 0.0, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.2f, 0.0, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.f, 1.f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.f, 1.f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.f, -1.f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.f, -1.f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.2f, 0.5f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.2f, -0.5f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.2f, -0.5f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(-1.2f, 0.5f, 0.0);
glEnd();
glBegin(GL_LINES);
glColor3f(255, 255, 255);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.2f, -0.5f, 0.0);
glEnd();
}
void main_loop_function() {
DrawCircle(0.0, 0.0, 1.45, 200);
glutSwapBuffers();
}
void GL_Setup(int width, int height) {
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
gluPerspective(45, (float) width / height, 0.1, 100);
glMatrixMode(GL_MODELVIEW);
}
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitWindowSize(window_width, window_height);
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
glutCreateWindow("trata");
glutIdleFunc(main_loop_function);
GL_Setup(window_width, window_height);
glutMainLoop();
}

Answer 1

This is just a quick fix to make your code work so you can fuhrtherly develop and debug it. I see a number of critical issues in your code:
(0) Mixing POSIX paths with Windows paths:
#include <GL/freeglut.h>
#include <GL\GL.h>
(1) including custom headers and expecting the community to guess what is it about. I commented it out.
//#include "stdafx.h"
(2) Miswriting casts as functions - it should be:
float theta = 2.0f * 3.1415926f * (float)ii / (float)num_segments;
(3) No glutDisplayFunc in your code. You should register something like:
glutDisplayFunc(main_display_function);
before registering glutIdleFunc(). Then, in your code you should define it somewhat in the following way:
void main_display_function() {
DrawCircle(0.0, 0.0, 1.45, 200);
glutSwapBuffers();
}
(4) Even in that function you don't clear the "window content" before redrawing:
void DrawCircle(float cx, float cy, float r, int num_segments) {
glClearColor (0., 0., 0., 1);
glClear (GL_COLOR_BUFFER_BIT);
{… … … } //the rest of your code
}
(5) Passing color values of wrong data type:
glColor3f(255, 255, 255); //unsigned byte passed, float expected!
or
glColor3ub(0.0, 0.0, 0.0); //float passed, unsigned byte expected!
There are few more issues which directly address your question - you will easily understand and debug them yourself, once you fix the program to work correctly (the order of calling glRotatef and the second glTranslatef, correctly computing movex, drawing beams or spokes). Please, also take a look at this SO post.
PS. Your using a C++ compiler to build this program doesn't make it a C++ code. There is not a single line of C++ specific code in your program. Also, both OpenGL and GLUT are plain-C APIs.