Polygon antialiasing

OpenGL
1

I’m having huge problems getting polygon antialiasing to work, developing in Visual C++ 6.0 running on Windows XP. Can someone have a look at my pixel format and tell me if it looks OK? This is the only thing I’m not sure about.

PIXELFORMATDESCRIPTOR pfd = { 
	sizeof(PIXELFORMATDESCRIPTOR),// size of this pfd 
	1,                            // version number 
	PFD_DRAW_TO_WINDOW |          // support window 
	PFD_SUPPORT_OPENGL |          // support OpenGL 
	PFD_DOUBLEBUFFER,             // double buffered 
	PFD_TYPE_RGBA,                // RGBA type 
	24,                           // 24-bit color depth 
	0, 0, 0, 0, 0, 0,             // color bits ignored 
	8,                            // alpha buffer 
	0,                            // shift bit ignored 
	0,                            // no accumulation buffer 
	0, 0, 0, 0,                   // accum bits ignored 
	32,                           // 32-bit z-buffer     
	0,                            // no stencil buffer 
	0,                            // no auxiliary buffer 
	PFD_MAIN_PLANE,               // main layer 
	0,                            // reserved 
	0, 0, 0                       // layer masks ignored 
};

Cheers,
Jamie.

2

Which anti-aliasing technique are you trying to use?

If it is multisampling, look at nehe tutorial. Note you have to first create a dummy window to query the multisample extension and then create a new one with multisample support: http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=46

If it is just the standard OpenGL anti-aliasing, just call
glEnable(GL_POLYGON_SMOOTH) for polygons. Note that if you have
multisampling enabled, this value is ignored.

If you have a GeForce>=8, you can also play with coverage sampled anti-aliasing: http://developer.nvidia.com/object/coverage-sampled-aa.html

3

Hi Overlay: I’m trying to use GL_POLYGON_SMOOTH antialiasing, I don’t want to use multisampling. I’ve got these commands in my initialisation:
glBlendFunc( GL_SRC_ALPHA_SATURATE, GL_ONE );
glEnable( GL_BLEND );
glDisable( GL_DEPTH_TEST );
glHint(GL_POLYGON_SMOOTH, GL_NICEST);
glEnable(GL_POLYGON_SMOOTH);
but the edges of polygons are not appearing antialiased.

Maybe it’s a problem with the Windows OpenGL library?

4

Even if you succeed in doing anti aliasing with GL_POLYGON_SMOOTH enabled you will be deceived… as Ilian Dinec said in your last thread. Furthermore it is not well supported.

You should try to use a more advanced methods like the ones Ilian or Overlay are suggesting.

5

OK, thanks for that advice!

I particularly want antialiasing so that my text looks better, converted from TrueType with wglUseFontOutlines. Will any particular antialiasing technique work best for that?

6

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