Draw rotating Torus with GLFW3

rotating_torus.cpp

// Draw rotating Torus with GLFW3
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>
#include <GLFW/glfw3.h>

static void drawTorus(int numMajor, int numMinor, float majorRadius, float minorRadius)
{
    static double PI = 3.1415926535897932384626433832795;

    double majorStep = 2.0 * PI / numMajor;
    double minorStep = 2.0 * PI / numMinor;


    glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

    for (int i = 0; i < numMajor; ++i) {
        double a0 = i * majorStep;
        double a1 = a0 + majorStep;
        GLdouble x0 = cos(a0);
        GLdouble y0 = sin(a0);
        GLdouble x1 = cos(a1);
        GLdouble y1 = sin(a1);

        glBegin(GL_TRIANGLE_STRIP);

            for (int j = 0; j <= numMinor; ++j) {
                double b = j * minorStep;
                GLdouble c = cos(b);
                GLdouble r = minorRadius * c + majorRadius;
                GLdouble z = minorRadius * sin(b);

                glNormal3d(x0 * c, y0 * c, z / minorRadius);
                glTexCoord2d(i / (GLdouble) numMajor, j / (GLdouble) numMinor);
                glVertex3d(x0 * r, y0 * r, z);

                glNormal3d(x1 * c, y1 * c, z / minorRadius);
                glTexCoord2d((i + 1) / (GLdouble) numMajor, j / (GLdouble) numMinor);
                glVertex3d(x1 * r, y1 * r, z);
            }

        glEnd();
    }
}


static void renderMesh()
{
    glLoadIdentity();
    glRotatef((float) glfwGetTime() * 50.f, 1.f, 1.f, 1.f);

    glBegin(GL_LINES);
        glColor4ub(255,0,0,255);    
        glVertex3f(0,0,0);
        glVertex3f(0.75,0,0);

        glColor4ub(0,0,255,255);
        glVertex3f(0,0,0);
        glVertex3f(0,0,0.75);

        glColor4ub(0,255,0,255);
        glVertex3f(0,0,0);
        glVertex3f(0,0.75,0);

    glEnd();
 
    drawTorus(10, 10, 0.5, .2);
}


int main()
{
    GLFWwindow* window;

    if(!glfwInit()) {
        fprintf(stderr, "Failed to start glfw\n");
        return -1;
    }

    //Set OpenGL Revision
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);
  
    //Create Window
    window = glfwCreateWindow(1000, 600, "OpenGL with GLFW", NULL, NULL);
    if (!window) {
        fprintf(stderr, "Failed to make window\n");
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    glfwSwapInterval(1);

    while (!glfwWindowShouldClose(window)) {
        double mx, my, t, dt;
        int winWidth, winHeight;
        int fbWidth, fbHeight;
        float ratio;

        glfwGetCursorPos(window, &mx, &my);
        glfwGetWindowSize(window, &winWidth, &winHeight);
        glfwGetFramebufferSize(window, &fbWidth, &fbHeight);

        ratio = (float)fbWidth / (float)winWidth;
        glViewport(0, 0, fbWidth, fbHeight);

        glClearColor(0.3, 0.3, 0.3, 1.0f);
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        renderMesh( );

        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwTerminate();
    return 0;
}