/*  call-seq:
 *    set_attrib( attrib, value )  ->  nil
 *
 *  Set the SDL/OpenGL attribute +attrib+ to +value+. This should be called
 *  *before* you call Screen#set_mode with the OPENGL flag. You may wish to
 *  use #get_attrib after calling Screen#set_mode to confirm that the attribute
 *  is set to the desired value.
 *
 *  The full list of SDL/OpenGL attribute identifier constants (located under
 *  the Rubygame::GL module) is as follows:
 *
 *  RED_SIZE::         Size of framebuffer red component, in bits.
 *  GREEN_SIZE::       Size of framebuffer green component, in bits.
 *  BLUE_SIZE::        Size of framebuffer blue component, in bits.
 *  ALPHA_SIZE::       Size of framebuffer alpha (opacity) component, in bits.
 *  BUFFER_SIZE::      Size of framebuffer, in bits.
 *  DOUBLEBUFFER::     Enable or disable double-buffering.
 *  DEPTH_SIZE::       Size of depth buffer, in bits.
 *  STENCIL_SIZE::     Size of stencil buffer, in bits.
 *  ACCUM_RED_SIZE::   Size of accumulation buffer red component, in bits.
 *  ACCUM_GREEN_SIZE:: Size of accumulation buffer green component, in bits.
 *  ACCUM_BLUE_SIZE::  Size of accumulation buffer blue component, in bits.
 *  ACCUM_ALPHA_SIZE:: Size of accumulation buffer alpha component, in bits.
 *  
 */
VALUE rbgm_gl_setattrib(VALUE module,VALUE attr,VALUE val)
{
  if(SDL_GL_SetAttribute(NUM2INT(attr),NUM2INT(val))==-1)
    rb_raise(eSDLError,"GL set attribute failed: %s",SDL_GetError());
  return Qnil;
}