|GPU Gems 3|
|author||Huber Nguyen (Editor)|
|summary||in-depth discussions of bleeding-edge techniques, tips, and tricks in real-time graphics and GPGPU.|
The first part of the book is about geometry with the first chapter diving right into generating complex procedural terrains on the GPU. This interesting chapter explains the techniques behind a recent NVIDIA demo that shows very nice, 3-dimensional, procedurally generated terrain using layering of multiple octaves of 3-dimensional noise. An interesting contribution of this chapter is how the authors texture the terrain avoiding the typical, ugly texture stretching that previous techniques exhibit. This is followed by a chapter on rendering a large amount of animated characters using new Direct3D 10 features, in particular the powerful geometry instancing that is now available. The author suggests doing palette skinning by storing bone matrices in animation textures instead of the traditional way where they are stored in shader constant registers. The next chapter is in a similar vein, but uses blend shapes aka morph targets instead of skinning to animate characters. In particular, the main focus is again on how to use Direct3D 10 features to accelerate blend shapes on the GPU. Other chapters in this part of the book are on rendering and animating trees, visualizing metaballs (also useful for rendering fluids), and adaptive mesh refinement in a vertex shader.
Part two of the book deals with light and shadows. For me personally, this is one of the most exciting parts of the book with very practical techniques that we are going to see applied fairly soon in video games. The first chapter is on summed-area variance shadow maps, an extension to the popular variance shadow maps algorithm that provides nice soft shadows without aliasing artifacts. The next chapter is on GPU-based relighting, which is mostly useful for fast previewing in offline rendering. Then we move on to a nice chapter on parallel-split shadow maps, which are a way of doing dynamic, large-scale environment shadows by splitting the view frustum into different parts and having a separate shadow map for each of them. Other chapters in this part of the book are on improved shadow volumes, high-quality ambient occlusion, which is an improvement of a technique previously presented in GPU Gems 2, and volumetric light scattering.
The third part of the book is on rendering techniques and it starts with a very interesting chapter on rendering realistic skin in real-time. This chapter with its more than fifty pages is one of the longest in the book, but it definitely deserves the space. I have never seen such realistic looking skin rendered in real-time before. The result is really astonishing and the authors go into detail of all the various techniques and tricks employed to achieve it. Simply put, they take a diffuse map and apply multiple Gaussian blurs of varying kernel sizes to it. These blurred images are then linearly combined using certain weights to get an approximation to a so-called diffusion profile, which is used to visualize subsurface scattering. Of course, the devil is in the details and the technique is a bit more complicated than what I've described here. Some other chapters in this part of the book are on capturing animated facial textures and storing them efficiently using principal component analysis (PCA) as used in recent EA Sports games, animating and shading vegetation in the upcoming game Crysis, and a way of doing relief mapping without the artifacts of previous methods.
Part four starts out with a chapter on true imposters, i.e. billboards generated by raytracing through a volumetric object on the GPU. It's fairly interesting but I doubt that we'll see it in video games anytime soon because the costs of this technique seem fairly high. Another chapter is on rendering large particle systems to lower resolution, off-screen buffers and then recombining them with the framebuffer as a post process. This technique allows for rendering very fill-rate intensive particle systems with good performance. Other chapters include an appeal to make sure you do your lighting calculations in linear space and be careful when and where gamma correction needs to be applied, followed by some chapters on post processing effects, in particular motion blur and depth of field, and a chapter co-authored by Jim Blinn himself on rendering vector fonts in high quality via pixel shaders.
With part five dealing with physics simulation on the GPU we enter GPGPU territory. While a lot of the techniques in this and the following part of the book are highly interesting and innovative, I doubt we'll be seeing them applied a lot in video games in the next year or two, simply because they use up a lot of GPU processing power and GPU memory that us game developers would rather spend on doing fancy graphics. The first chapter is on doing rigid body simulation on the GPU. The author uses spherical particles to represent rigid bodies, which greatly simplifies the collision detection even between the most complex shapes. The subsequent chapter is on simulating and rendering volumetric fluids entirely on the GPU. The authors apply fluid simulation to create realistic smoke, fire, and water effects. The presented technique is based on running a fluid simulator on a voxelized 3D volume stored in 3D textures. Also solid objects that interact with the fluid are voxelized on the fly on the GPU. To render the fluid a ray-marching algorithm is used. The remaining chapters of this part of the book discuss N-body simulation, broad-phase collision detection and convex collision detection with Lemke's algorithm for the linear complementarity problem. Many chapters of this part of the book use NVIDIA's new language for doing GPGPU called CUDA and the reader is expected to be familiar with it. CUDA is both a runtime system and a language based on C that eliminates the need to have in-depth knowledge of a graphics API in order to implement GPGPU algorithms.
The final part of the book is on GPU computing with chapters that show how to apply the incredible parallel computing power of modern GPUs to classic computation problems that are not directly related to either computer graphics or physics. One chapter demonstrates how to search for virus signatures on the GPU, effectively turning your graphics card into an antivirus scanner. Another chapter shows how to do AES encryption and decryption on the GPU, which is now possible thanks to the new generation of GPUs supporting integer operations in addition to floating-point operations. Other chapters deal with generating random numbers, computing the Gaussian, and using the geometry shader introduced with Direct3D 10 to implement computer vision algorithms on the GPU that previously were not possible with vertex and pixel shaders only, such as histogram building and corner detection.
One of the features that distinguishes the GPU Gems series from other graphics books was kept for GPU Gems 3: the high quality and large number of images and diagrams. All figures in the book are in color, and there are plenty of them. The book also comes with a DVD that has the sample source code to most of the techniques discussed in the book. A lot of these programs require Direct3D 10 hardware (and as consequence Windows Vista) to run. However, for most of these, demo videos are also made available so you can see how a technique looks like without having the latest hardware or operating system. Furthermore, the book's website offers a visual table of content and three sample chapters to download in PDF format.
As with the previous two GPU Gems books, most of the chapters in this book are fairly advanced and ahead of their time. A lot of the presented techniques are not yet practical for video games on current generation GPUs, simply because they use up all the computation power and/or memory that they have to offer. However, a lot of techniques from the previous two books are now commonly used and we can expect the same to be the case for many of the techniques discussed in this book. As such, it is required reading for any serious professional working in the real-time computer graphics industry.
Martin has been involved in real-time graphics programming for more than 10 years and works as a professional game developer for High Moon Studios in sunny California.
You can purchase GPU Gems 3 from amazon.com. Slashdot welcomes readers' book reviews -- to see your own review here, read the book review guidelines, then visit the submission page.