private void present(){
  glUseProgram(quadProgram);
  glBindBuffer(GL_ARRAY_BUFFER,vbo);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D,tex);
  glDrawArrays(GL_TRIANGLES,0,6);
  glActiveTexture(GL_TEXTURE0);
  glBindTexture(GL_TEXTURE_2D,0);
  glBindBuffer(GL_ARRAY_BUFFER,0);
  glUseProgram(0);
}

private void present ( ) { glUseProgram ( quadProgram ) ; glBindBuffer ( GL_ARRAY_BUFFER , vbo ) ; glActiveTexture ( GL_TEXTURE0 ) ; glBindTexture ( GL_TEXTURE_2D , tex ) ; glDrawArrays ( GL_TRIANGLES , 0 , 6 ) ; glActiveTexture ( GL_TEXTURE0 ) ; glBindTexture ( GL_TEXTURE_2D , 0 ) ; glBindBuffer ( GL_ARRAY_BUFFER , 0 ) ; glUseProgram ( 0 ) ; }
present the final image on the screen / viewport .
