   glRasterPos() problem
  Well I dont know how this function works (glRasterPos2i()). But in the book it says that this Raster Position will be the position of  lower left cornor of the bitmap . But I tried like millions times. And there is nothing appear on my screen.If I tried ignore this function my bitmap will be appeared at left lower cornor of my viewpoint.Here's my code.. sry for this format I dont know how to use another format for putting codes in.int width = 800;int height = 600;glViewport(0, 0, width, height);glMatrixMode(GL_PROJECTION);glLoadIdentity();glOrtho(0.0f, width - 1.0, 0.0, height - 1.0, -1.0, 1.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();unsigned char A[] = {0xC0, 0x03,0xC0, 0x03,0xC0, 0x03,0xC0, 0x03,0xC0, 0x03,0xDF, 0xFB,0x7F, 0xFE,0x60, 0x06,0x30, 0x0C,0x30, 0x0C,0x18, 0x18,0x18, 0x18,0x0C, 0x30,0x0C, 0x30,0x07, 0xE0,0x07, 0xE0};glPixelStorei(GL_UNPACK_ALIGNMENT, 1);glRasterPos2i(20,30);glBitmap(16,16,0,0,0,0,A);Well Im very newbie on computer graphic. But I tried set raster position. How matter what value I assign it still dissapear.   
  What about everything else that may affect the fragment color, like texturing, lighting and primary color, are they disabled and/or set to proper states? What about depth test, is the bitmap in front of everything drawn before if depth testing is enabled?By the way, remove the two -1.0 after width/height from glOrtho. With them, you create a view volume that is (width-1, height-1) units in size, while the viewport is (width, height) pixel in size. That gives you the wrong mapping from object coordinates to window coordinates.   ;  Hmm... seems the problem came from the object coordinates and windows coordinate like you said. I triedgluOrtho2D(0.0, width - 1.0, 0.0, height - 1.0); and it works.And I tried put modelview matrix before drawing the bitmaps and set viewport out from projection matrix. Now it works fine. Thanks a lot for the hint.   ;  The call to glOrtho in the original code and the call to gluOrtho2D produces exactly the same projection matrices, so I doubt the last one works but not the first. You must have done something else.And you still have those -1.0 after width/height. For a one to one mapping of object coordinates to window coordinates, you should remove it.   