Need Once Again Help :)

OpenGL OpenGL: Basic Coding
1

Respected SIr / Maam :slight_smile:
After Running the given Code on Linux,the following issues Arises.kindly Give solution for these :slight_smile:
1: after compiling,the executed window is transparent

this is the code ==>
#include <GL/glut.h>
#include <math.h>
void Soccer_Field (void)
{
float x, y, ang, radius = 0.05;
static float RAD_DEG = 57.296;

glBegin (GL_QUADS);
   glColor3f  (0.20, 0.60, 0.20);                           // GreenYard
   glVertex2f (0.10, 0.10); glVertex2f (0.90, 0.10);
   glVertex2f (0.90, 0.90); glVertex2f (0.10, 0.90);
   glColor3f  (1.0, 1.0, 1.0);
   glVertex2f (0.90, 0.35); glVertex2f (0.83, 0.35);        // Inner White Quad - Right
   glVertex2f (0.83, 0.65); glVertex2f (0.90, 0.65);
   glVertex2f (0.10, 0.35); glVertex2f (0.17, 0.35);        // Inner White Quad - Left
   glVertex2f (0.17, 0.65); glVertex2f (0.10, 0.65);
glEnd ();

glColor3f (0.0, 0.0, 0.0);                                  // Change color to black

glBegin (GL_LINES);
   glVertex2f (0.50, 0.10); glVertex2f (0.50, 0.90);        // Mid Line

   // Left side of the Ground
   glVertex2f (0.25, 0.25); glVertex2f (0.25, 0.75);        // Goal keeper front line
   glVertex2f (0.10, 0.75); glVertex2f (0.25, 0.75);        // Goal keeper left line
   glVertex2f (0.10, 0.25); glVertex2f (0.25, 0.25);        // Goal keeper right line

   // Right Side of the Ground
   glVertex2f (0.75, 0.25); glVertex2f (0.75, 0.75);        // Goal keeper front line
   glVertex2f (0.75, 0.25); glVertex2f (0.90, 0.25);        // Goal keeper left  Line
   glVertex2f (0.75, 0.75); glVertex2f (0.90, 0.75);        // Goal keeper right line
glEnd ();

glBegin (GL_LINE_LOOP);                                     // Circle at center of field
   for (ang = 0.0; ang &lt; 360.0; ang += 10.0)  {
      x = radius * cos(ang/RAD_DEG) + 1.0;
      y = radius * sin(ang/RAD_DEG) + 0.5;
      glVertex2f (x/2.0, y);
   }
glEnd ();

}
void Initialize()
{
glClearColor(0.60, 0.40, 0.12, 0.20);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-100, 100, -50, 50, -1, 1);
}
int main(int iArgc, char** cppArgv)
{
glutInit(&iArgc, cppArgv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize(900, 450);
glutInitWindowPosition(200, 200);
glutCreateWindow(“Football Ground OpenGL”);
Initialize();
glutDisplayFunc(Soccer_Field);
glutMainLoop();
return 0;
}

2

Try adding ‘glClear(GL_COLOR_BUFFER_BIT)’ to the top of the ‘Soccer_Field’ routine.

Also, change the glOrtho parameters back to what you had before.

3

Sir it worked fine by adding glClear(GL_COLOR_BUFFER_BIT); <3 awesome thank you so much help <3 May God Help and bless you <3

4

sir that is true method to create circle in openGl but also give a short lecture on creating circle .if i want to create a circle on an other place then what i should do .i am confused about position/vertex of circle that how i change the place of circle and also change the size of circle thanks.:slight_smile:
please help me out …

5

I suggest you experiment with the circle routine I posted. Try changing some of the numbers to see what happens. The size, position, and shape of the circle can all be controlled by changing those numbers.