Offroad Racing (C++, SDL, OpenGL)

My bachelor project at Czech Technical University from year 2006. It's a simple linux game written in C++ (using SDL library) based on my own physics engine (spring systems and rigid body dynamic simulation) and large terrain rendering (heightmap has 2550x2550 pixels) imported from OpenTTD game. Collision detection is ensured by space grid subdivision and bounding sphere hierarchies. Collision response uses penalty force method. Tyre simulation is based on simplified Pacejka's method. Physics engine calculates transfer of forces from vehicle engine through clutch and gearbox to wheels. Renderer uses OpenGL and GLSL shaders. More details and download at my web pages: http://milantimko.info .

Category:

Science & Technology

Tags:

• c++
• opengl
• glsl
• shaders
• sdl
• physics
• engine
• game
• linux
• rendering
• terrain
• rigid body
• bounding sphere hierarchies
• collision detection
• heightmap
• tyre simulation
• Pacejka
• bachelor thesis
• czech technical university
• cvut
• openttd
• karosa
• skoda
• octavia
• skoda 120
• skoda favorit
• bus simulator
• linux game
• per-pixel
• fragment shader
• phong
• gearbox
• transmission
• landscape
• multiplatform
• penalty force
• Simulation
• Simulation Game

[Tasaq313]

How did you do terrain collisions? I mean that car drives uphill

[mtimko83]

@Tasaq313

Collisions are done by penalty force method. Engine calculates how deep is wheel (or other car part) under the terrain and then applies appropriate force to push it up.

[Tasaq313]

@mtimko83 hmmm, but how do you check that part is under terain? I am taking my terain from 3ds max, so i don't use heightmap... also i like your idea to cover a car with multiple colispheres :)

[mtimko83]

@Tasaq313 I think the simplest way is to implement triangle-point collision detection algorithm and test every point of vehicle geometry with every triangle of terrain mesh. This approach is of course very slow so you'll need some optimizations like bspheres or other simplified collision geometry to represent car model. Also subdividing terrain into smaller areas to limit number of triangles per one collision test is a good idea (using regular terrain grid, I can limit it to one).

[staticVoid2]

Do you use SAT for collision or just spheres?

[mtimko83]

@staticVoid2

Just spheres. But I'll definitely use convex components (and SAT) next time, it's much more handy for cars.

[s5zone]

this is awesome, i love the bus

[kindofgameplay]

really cool engine! love the physics keep it up!

[Tasaq313]

@mtimko83 Thanks, I alread am trying to do that, but I have problems with geting triangles from my loader, I think it will take my some time to figure that out:)

[JustJealouse514]

lol you reused the same project..