Skip to main content

Jet: Cascading Shadow Maps

This is a demo of my homegrown cascading shadow mapping.  Notice how the shadows remain sharp at all distances.  This is currently using 4 2048 byte shadow textures, but it looks similar with 1024 byte textures. Cascading shadow maps work by dividing the view frustum into sections, and assigning a shadow texture to each section.  This allows shadows to be rendered at great distance without loss of visual fidelity during close-up shots of a shadow.  The great thing about shadow mapping is that you get self-shadowing for free.

The performance isn't too bad either.  This demo ran at 270 frames per second on my EVGA 8800 GTS, with normal mapping and specular mapping.  Modern GPUs have really great texture lookup performance: the shader I wrote for this demo performs 7 texture lookups per pixel (1 for normal mapping, 1 for the diffuse map, 1 for specular mapping, and 4 for shadow mapping).  A previous iteration of this demo (with only 1 shadow texture lookup) ran on an Intel GMA at 35 frames per second, which isn't bad for an integrated graphics card.

The performance of this demo is fill-rate bound.  This is actually good, because it means I have plenty of vertex processing and CPU overhead to work with.  Also, most of the fill-rate-intensive shader work is done already so I don't really need anymore fill-rate.

My next couple of goals: multiple shadow-casting lights, spotlights, and point lights.

Comments

Post a Comment

Popular posts from this blog

Lua-Style Coroutines in C++

Lua's implementation of coroutines is one of my all-time favorite features of the language. This (short) paper explains the whole reasoning behind the Lua's coroutine implementation and also a little about the history of coroutines. Sadly, coroutines are not supported out-of-the box by many modern languages, C++ included. Which brings me to the subject of this post: Lua-style coroutines in C++! For those who don't know (or were too lazy to read the paper!), Lua's coroutines support three basic operations: Create: Create a new coroutine object Resume: Run a coroutine until it yields or returns Yield: Suspend execution and return to the caller To implement these three operations, I'll use a great header file: ucontext.h. #include <vector> #include <ucontext.h> class Coroutine { public: typedef void (*Function)(void); Coroutine(Function function); void resume(); static void yield(); private: ucontext_t context_; std
9 comments
Read more

Password Generator for Chrome

This week, I finally got fed up with typing in/managing passwords on a billion different sites. Since things like OpenID haven't really taken off, I decided to take matters into my own hands...and write a password generator extension for Google Chrome. There are actually a ton of such apps on the Chrome web store, but I'm paranoid about security, so I wrote my own and open-sourced it. By virtue of being open source, perhaps people will trust my version a bit more. Anyway, the extension is available here , and the source code is hosted at github . May all your online transactions be secure! UPDATE: Fixed github link.
2 comments
Read more

Warp

So, it turns out that I didn't use Criterium for the video game competition at Stanford.  I actually met a partner and went with another concept instead -- Warp.  It's kind of like Starfox and it's inspired by Rez, one of the first PS2 games.  Explosions and missiles fire in time with the music; we used ChucK , an audio processing language, to achieve this. We also made some destructible objects using rigid bodies, and I added some particle explosion effects.  We used Lua to for enemy AI, and wrote a small TCL-like script parser that reads in data for the level layout.  The buildings in the background are procedurally generated.  We used OGRE for the graphics (this was a loose requirement of the project) and Bullet for the physics.  I had a lot of fun with this project, and I've posted a video capture below.
1 comment
Read more