Skip to main content

Criterium: Roads

Roads are tricky.  They have to match the terrain; they have to bank, curve, swerve and whatnot.  I have three ideas for roads, and no idea is trivial to implement.  All my ideas output a road mesh with a rectangular cross section, so there will be no gaps between the road and the underlying terrain.  The road will actually be a rectangular "tube" with only the top of the tube showing above the terrain.

First up is procedural generation of roads.  For this scheme, I would first generate the terrain heightmap.  Then, the roads could be generated by following contours, making random changes in direction, or making random jumps to different contours.  In the end, the procedural algorithm would output a list of waypoints for the road, and a mesh could be generated from the waypoints.

Second is direct creation of the road mesh.  I would have to make a modeling tool for the road, and extrude road segments from the end of the road.  Perhaps Bezier curves and control points could be used to manipulate curves in the road (both vertical and horizontal).

My last idea is a combination of the last two.  I could paint the road waypoints on top of a 2D texture, and then have an algorithm calculate the appropriate height of the road at each point.  The algorithm would need the heightmap as an input to calculate the road height.

That's all for now, more ideas soon.


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


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.

Sparse Voxel Octrees

Terrain implementation for games is a subject with a lot of depth. At the surface, it's very easy to get rudimentary terrain working via a noise function and fixed triangle grid. As you add more features, though, the complexity builds quickly. Overhangs, caves Multiple materials Destructive terrain Collision detection Persistence Dynamic loading Regions, biomes Very large scale Smooth features Sharp features Dynamic level of detail Extremely long view distances In isolation, each of these features can make terrain difficult to implement. Taken together, it takes a lot of care and attention to make it all work. Minecraft is probably the canonical example for terrain generation in the last generation of games. In fact, I'd say Minecraft's terrain is the killer feature that makes the game so great. Minecraft does an excellent job at 1-8, but for a recent planetary renderer project I was working on, I really wanted 9-12 too. In a series of articles, I'm planning to break do