Circles Within Circle OpenGL Code

We can create multiple circles within a Circles in OpenGL, with the following code, you can change the radius Color and width according to your own requirement.

   1:  #include<Windows.h>

   2:  #include<glut.h>

   3:  #include<math.h>

   4:   

   5:  void DrawCircle(float x, float y, float radius)

   6:  {

   7:      float DEG_RAD = 3.14159/180;

   8:      glBegin(GL_LINE_LOOP);

   9:   

  10:     for (int z=0; z<=360; z++)

  11:     {

  12:        float deg = z*DEG_RAD;

  13:        glVertex2f(x+cos(deg)*radius,y+sin(deg)*radius);

  14:     }

  15:     glEnd();

  16:  }

  17:  void Draw()

  18:  {   

  19:      glClear(GL_COLOR_BUFFER_BIT);

  20:      glColor3f(1.0 , 0.0, 0.9);

  21:      DrawCircle(0.0,0.0,0.9);

  22:      glColor3f(0.0 , 1.0, 0.0);

  23:      DrawCircle(0.0,0.0,0.7);

  24:      glColor3f(1.0 , 1.0, 0.0);

  25:      DrawCircle(0.0,0.0,0.5);

  26:      glColor3f(1.0 , 1.0, 1.0);

  27:      DrawCircle(0.0,0.0,0.3);

  28:      glEnd();

  29:      glFlush();

  30:  }

  31:   

  32:  void Initialize()

  33:  {

  34:      glClearColor(0,0,0,1);

  35:      glMatrixMode(GL_PROJECTION);

  36:      glLoadIdentity();

  37:      glOrtho(0.0, 0.0, 0.0, 0.0, -1.0, 1.0);

  38:  }

  39:   

  40:  void main(int iArgc,char** cppArgv)

  41:  {

  42:      glutInit(&iArgc,cppArgv);

  43:      glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);

  44:      glutInitWindowPosition(400,200);

  45:      glutInitWindowSize(500,400);

  46:      glutCreateWindow("Circles Within Circle by Muhammad Taqi :: www.techgulf.blogspot.com");

  47:      Initialize();   

  48:      glutDisplayFunc(Draw);

  49:      glutMainLoop();

  50:  }