title: Opengl Setting image coordinates with glTexCoord2f
body: <p>Im working on a project in opengl c++. Im trying to create a skybox and i 've been able to create all the 4 faces with the right textures with the right image coordinates. But i'm having a problem at the upper face.I can't set properly the image coordinates. This is the code:</p>
  
  <pre><code>glBegin(GL_QUADS); // back
  glTexCoord2f(0.0f, 1.0f); glVertex3f(-size , height , -size);
  glTexCoord2f(1.0f, 1.0f); glVertex3f( size , height , -size);
  glTexCoord2f(1.0f, 0.0f); glVertex3f( size , -17.00f , -size);
  glTexCoord2f(0.0f, 0.0f); glVertex3f(-size , -17.00f , -size);
  glEnd();
  
  //left
  glBindTexture(GL_TEXTURE_2D, skytexture[1]);
  glBegin(GL_QUADS);
    glTexCoord2f(1.0f, 1.0f); glVertex3f(-size , height , -size);
    glTexCoord2f(0.0f, 1.0f); glVertex3f(-size , height ,  size);
    glTexCoord2f(0.0f, 0.0f); glVertex3f(-size , -17.00f , size);
    glTexCoord2f(1.0f, 0.0f); glVertex3f(-size , -17.00f ,-size);
  glEnd();
  
   //front
  glBindTexture(GL_TEXTURE_2D , skytexture[3]);
  glBegin(GL_QUADS);
  glTexCoord2f(0.0f , 1.0f);glVertex3f( size  , height , size);
  glTexCoord2f(1.0f , 1.0f);glVertex3f( -size , height , size);
  glTexCoord2f(1.0f , 0.0f);glVertex3f( -size , -17.0f ,  size);
  glTexCoord2f(0.0f , 0.0f);glVertex3f(size ,   -17.0f , size);
  glEnd();
  
  
  //right
   glBindTexture(GL_TEXTURE_2D, skytexture[2]);
   glBegin(GL_QUADS);
   glTexCoord2f(0.0f , 1.0f); glVertex3f(size , height , -size);
   glTexCoord2f(1.0f , 1.0f); glVertex3f(size , height ,  size);
   glTexCoord2f(1.0f , 0.0f); glVertex3f(size , -17.00f , size);
   glTexCoord2f(0.0f , 0.0f); glVertex3f(size , -17.00f ,-size);
   glEnd();
  </code></pre>
  
  <p><strong>//------ HERE IS THE PROBLEM WITH SETTING THE COORDINATES</strong>
  <strong>//------ THE RESULT IS MESSED UP</strong></p>
  
  <pre><code> //up
   glBindTexture(GL_TEXTURE_2D , skytexture[4]);
   glBegin(GL_QUADS);
   glTexCoord2f(0.0f , 0.0f);glVertex3f(-size , height , -size);
   glTexCoord2f(1.0f , 0.0f);glVertex3f( size , height , -size);
   glTexCoord2f(1.0f , 1.0f);glVertex3f( size , height , size);
   glTexCoord2f(0.0f , 1.0f);glVertex3f(-size , height , size);
   glEnd();
  </code></pre>