Lessons 41 - 45

	Volumetric Fog & IPicture Image Loading This tutorial will introduce you to the world of extensions. In this tutorial you will learn how to create Volumetric Fog using the glFogCoordf Extension. You will also learn how the IPicture code works, and how to use it in projects of your own. Because of very limited free time, the demo is not all that complex. The only keys used in this demo are the up and down arrow keys. The only effect displayed in this demo is volumetric fog. Keeping that in mind, the fog effect is extremely cool, and the tutorial is very detailed. After reading through this tutorial you should have no problem adding volumetric fog to demos of your own. It's important to note that this tutorial only runs on video cards that support the EXT_fog_coord extension. If you are not sure if you care supports this extension, download lesson 24 and scroll through the list of supported extensions. Hopefully someone will find this code useful!
	Multiple Viewports This tutorial was written for all those people that have emailed me wanting to know how to display multiple views on a single screen. This tutorial will teach you how to set up multiple viewports, how to display both ortho and perspective views on the same screen, and how to display a variety of effects with each effect running in it's own viewport. As an added bonus, you will learn how to get the size of your OpenGL window, you will learn a very fast way to update a texture without rebuilding it. You will learn how to use GL_COLOR_MATERIAL to color a texture and you will get to play around with my maze code :) I hope you appreciate the time I put into making this tutorial. It a simple idea, but writing the tutorial and then the HTML was very time consuming!
	FreeType Fonts in OpenGL Recently many of you have written to me asking how to create an anti-aliased font. Bitmap fonts are usually blocky looking when zoomed, and outline fonts eat up too much CPU. Thanks to Sven Olsen, you can now create extremely nice looking fonts using the FreeType library. By using the FreeType library you can create anti-aliased text. The text is easy to rotate and works well with OpenGL's picking functions. The example program is based on lesson 13, and uses the older NeHe basecode. The example is not all that fancy, but after running it, you will see a clear difference between the older WGL Bitmap Font and the new FreeType Font! If you enjoy this tutorial, please email the author and let him know!
	3D Lens Flare With Occlusion Testing Learn how to do lens flares by extending a glCamera class. If you look at a lens flare you will notice that they all share one thing in common. They all seem to move through the center of the screen. With this in mind you could actually just throw out the z coordinate and make your flares all 2D. The only problem with this approach is without a z coordinate how do you find out if the camera is looking at the light source or not? In this tutorial we will be making 3D lens flares so get ready for a little bit of math. Occlusion test by Dario Corno a.k.a. rIO of Spinning Kids.
	Vertex Buffer Objects When you need raw polygon-pushing power, you can always utilize the optimizations provided by OpenGL. Vertex Arrays are one good way to do that. For even more boost you can use a recent extension to graphics cards called 'Vertex Buffer Objects'. The extension, ARB_vertex_buffer_object, works just like vertex arrays, except that it loads the data into the graphics card's high-performance memory, significantly lowering rendering time. Because the extension is relatively new, not all cards will support it. This awesome tutorial was written by Paul Frazee. If you enjoy the tutorial please e-mail him and let him know.