CS 446: Real-Time Rendering
Assignment #4

Synopsis: Pick a component to add to your game engine from one of the categories below.

Due: This assignment is due Tue Mar 21.  By Tue Mar 14 (Tuesday after Spring Break) you should mail me and Ryan a description of what project you plan to do and how it will fit into your game. This is important! On Thursday, Mar 23, the group will demonstrate all of the individual effects incorporated together into the group's rendering engine.

Grading: You will get an individual grade for completing the project (and 40% of your total grade comes from these individual project grades). You will be graded on completeness, difficulty of task, and polish, in that order of importance. Repeat: you will be graded on the difficulty as well as the success rate of your projects.  Not every project has to be a killer, but I expect every student to take on at least one substantially difficult project, and no more than one comparatively easy project.  Part of the reason you need to mail me a description of what you plan to do is to so that I can give feedback, if necessary, on how difficult I judge a project to be. 

Note that I explicitly do not want four individual assignments that don't work together.  Your project must be fully integrated with the group's game engine. To enforce this, part of the "Group Project" grade (worth 35% of your total grade) comes from the "integration" deadline two days after the individual assignments are due. If your individual project doesn't work with the rest of the group's work, it may be considered late (burning late days and accumulating late penalties) until it does. At the integration deadline the group will turn in one (and only one!) codebase.

Details: The next three assignments in the class will follow the same pattern.  Each student must pick one project from the following categories, with the constraint that no student can pick more than one project from any category (but note that some projects fit multiple categories), and with the additional constraints noted below. If you have an idea for a project that doesn't fit into the below list, bring it up with me (soon!).

1. Lighting effects: add some interesting lighting effects to your system:
   • Light maps: precomputed (or even hand painted) textures that capture low-frequency lighting information, combined with surface texture using multitexturing.
   • Shadows: shadow maps, shadow volumes, various soft shadow algorithms, others.  Note: every group must implement a shadow algorithm at some point during the semester. 
   • Flare and glare effects: lens flare, optic glare, and chromatic aberration effects lend a sense of "photorealism" by simulating camera effects familiar from cinema.
   • Volumetric light effects: add "shafts of light", for example using techniques similar to shadow volumes.
2. Texture effects: add texture-related effects to your system:
   • Light maps: see above
   • Decals: these are things like bullet holes, char marks, and spattered blood (to pick typical if violent examples) that get dynamically added to the scene by player actions.
   • Normal maps: write shaders to add visual detail to your polygons by perturbing the normal used in lighting according to a texture.
   • Imposters: add image-based imposters (dynamic or preprocessed)
   • Environment maps: use environment maps to get convincing glossy or reflective objects
   • Projective texturing: this technique projects a texture onto a surface like a slide projector.  Lots of special effects possible this way.
3. Shaders: use Cg to implement interesting surface shaders in your engine
   • Normal maps: see above
   • NPR/toon shading: per our discussions in class.
   • Skinning: implement skinning on articulated characters.
   • Particle systems: write a vertex program to create time-varying particles: since vertex programs can calculate the vertex position as a function of time, they can be used to implement simple physical or non-physical particle systems.  For example, a vertex shader can compute the effects of gravity and wind on falling sparks.  Games use this technique frequently to implement explosions, fire, water, grass blowing in the wind, hair, "swarming points of light" magic effects, and yes, splashing blood.  You will probably want to combine such particle systems with the NV_POINT_SPRITE extension, which allows you to draw each vertex as a screen-aligned quadrilateral with a (possibly animated) texture applied. 
   • Deferred shading: if you want to use a very complicated shader on lots of geometry in the model, it can be expensive to run that shader on pixels that eventually get depth-buffered away.  Deferred shading instead writes the shader parameters (e.g., normal, texture coordinates) to the framebuffer, then makes a pass over the entire screen by drawing a screen-sized quad with the framebuffer applied as a texture, and running the very complicated shader on just those pixels that survived the depth test. 
4. Performance: Speed up your engine using acceleration techniques or just careful tuning.
   • Visibility: add portal culling, PVS managment, or some other form of occlusion culling.
   • LOD: add LOD preprocessing or run-time LOD management for objects, terrain, or shaders.
   • Imposters: add image-based imposters (dynamic or preprocessed).
   • Performance: profile, optimize, and tune your game engine to make it go as fast as possible.
5. Other stuff: a catch-all final category for some of the many other things that go into a good game.
   • Tools: build some tools for artists or level builders in 3DS Max or Maya
   • Physics: add some physical simulation to your game.
   • AI: add some AI to your game.
   • Special effects: fur, npr edge-based effects, water effects, clouds and fog, transparency, etc.
   • Camera control: intelligent "cinematic" camera control, instant replay, etc.
   • Art: increase visual richness by investing substantial effort to add non-trivial art assets to your game.

There are a few additional constraints.  Across the remaining four assignments:

1. Every group must implement a shadow algorithm
2. Every group must implement at least two acceleration or tuning projects from the "Performance" category.
3. Every group must employ multitexturing at some point
4. Two group members may not do the same project (though some projects allow for sufficient variation that they would not really be the same project. Just use common sense and check with me if you are not sure.)

 Resources: Similar list as before, with a couple new bullets.  Feel free to amplify this list by sharing your own comments and pointers on the class forum.

• www.gamasutra.com: Lots of useful information on game programming here, along with some chaff.
• http://www.gametutorials.com: a soup-to-nuts series of inexpensive source code "tutorials" on game programming, written for beginning programmers but containing some useful information. The tutorials are in the form of heavily-commented source code.  In particular there are fairly good tutorials on loading some different 3D file formats.
• http://lib3ds.sourceforge.net: a library for reading .3ds files, seems fairly complete.
• www.planetquake.com/polycount: lots of models for various games. 
• http://www.turbosquid.com: Models, textures, and other assorted downloads for 3D graphics & game development. Some stuff for free, lots of stuff for sale (often at extremely low prices).
• 3D Studio Max files: I have purchased a collection of over 5000 models in 3D Studio .max  format (not the same as .3ds), available at \\cs-tl4\3dEnc2000 in Windows.  You can export these models (for example, to .3ds format...) and create new ones using 3D Studio Max, which is (or will be) available in 002a. You can browse these models more conveniently at http://www.deespona.com/3denciclopedia/menu.htmll.
• http://shadertech.com: Plenty of sample shaders, some of them simply gorgeous, and forums where people will help you with dumb or not-so-dumb questions about Cg and programmable graphics. Update: looks like this site hasn't been updated in over a year, and the forums are down "temporarily", so it may not be as useful as it once was.
• http://developer.nvidia.comm: Tons of presentations, white papers, tools, and demos (with code!) explaining how to achieve various effects, or how to tie them together in a game engine.  Poorly organized but lots of great information. In particular you will want to download the complete Cg Toolkit, which includes documentation and examples for programming in Cg, and the NVSDK.
• Papers!  Many algorithms are best described in the papers where they were first presented.  Browse the programs and proceedings of conferences like SIGGRAPH, the Symposium on Interactive 3D Graphics, Eurographics and it's subsidiary workshops/symposia, Graphics Interface, and Pacific Graphics.  Look on researcher's web pages for copies of the papers; sometimes you'll also find slides, movies, or even code demonstrating their techniques. You can also find lots of very useful materials in presentations and tutorials given at Game Developers Conference (GDC).
• I have a beta version of the book "Essential mathematics for games". It's a very thorough yet readable introduction to the math underlying computer graphics techniques, ranging from affine transformations to quaternions and splines to the lighting equation to rigid-body dynamics.  Come check it out if you like.

Also, don't forget about the optional texts for the course like the Cg Tutorial and the Game Programming Gems series!

Policy on code reuse: Same policy: In general you are welcome to use code that you find elsewhere.  For example, you are welcome to use the lib3ds library mentioned above, and you are strongly encouraged to use the in-house software tools that Ben has posted.  However, you will not get credit for what you didn't write.  Therefore, it is critically important that you describe in detail what code you wrote yourself and what code you imported or adapted from elsewhere.  Furthermore, if you find a particularly helpful library, tutorial, loader, etc., you should post it on the forum.  Obviously if you reuse a significant amount of code, that raises the bar for the assignment: you will be expected to do something beyond the basics mentioned above.  If you have any questions about code reuse or attribution, please ask me.

Turning in the assignment: On the individual due date, you will arrange to demo your working effect or project to the TA. For the integration deadline two days later, the group should turn in a single working program that demonstrates the various features added by individuals. Put all your code and models in a folder, along with a detailed README.txt file that describes what your group did, who in the group did what, and any code or features added that aren't specifically part of an individual assignment (I expect that during every project, there will be some effort on the general game engine that is not reflected in an individual assignment.  You will get credit for these efforts as a group, and yes, general work on the game outside of the individual assignments will benefit the group's grade as a whole). 

Each student in the group should include a separate document, e.g. README.luebke.txt, that describes in detail what you did, how you did it, what code you used from elsewhere, and how to demo your contribution in the game engine.  Zip up the folder and e-mail the .zip file (or a link) to me and the TA.  Be sure to include workspace and project files, along with any libraries/include files/etc, so that we can compile your code.  We will read (and grade you on) your source code, so follow good programming practices.