A simple game as part of the TFAY87 Physics course
##Description Rymdbiljard is a simple game build in Rust built as part of the TFYA87 Physics Course at Linköping University. Rymdbiljard is a basic billiards game in which the player is faced with the problem of knocking all poolballs into some goal-zone by hitting them with the white poolball of which he/she has control over.
The project relies on some third party libraries mainly nalgebra for linear algebra calculations and Piston for rendering. The entire physics engine is written from scratch and includes collision detection and collision handling. There are two types of collisions which are supported; ball-to-ball and ball-to-wall. The physics engine also includes friction and gravitation simulations. The frictions is done between the balls and the "floor", and the gravitation is done between "blackholes" and the poolballs.
To calculate the physics we use a time step solution which simulates how the objects properties would change over the time in a given step. The step time will vary between different steps.
Some assumptions has been made to simplify the physics engine in terms of simplifying the actual physics. First, we regard all collisions as fully elastic, i.e that there exists no energy loss. Second, the gravitational pull from a blackhole has a maximum reach to improve game-play. This means that force is only exerted on balls within the specified reach. Third, the poolballs "glide" over the floor instead of rolling and no spin is possible. Thus there is no consideration to rotational momentum as this would complicate both collision detection and resolution. Last, all constants in the physical formulas has been tweaked considerably to improve gameplay, this includes both gravitational constant as well as the friction coefficient between the poolballs and the floor.
The most interesting part of the project is the collision detection and resolution algorithms. To ensure that all collisions are resolved in the correct order we do the following:
- Calculate the collision time for all collisions that will happen if the objects continue with their current velocity.
- Pick the collision which happens first and simulate the movement of all objects up to that time
- Solve the collision found in step 2 (We use perfectly elastic collisions)
- Repeat until no collisions are found or all collisions found happen after the time of our current time step
The documentation for the head of the master branch is available online at https://holmgr.github.io/rymdbiljard/, and is built automatically. If you wish to build the documentation locally or for branch or state other than the master head then the following command can be issued in the project root:
cargo rustdoc --open -- --no-defaults --passes collapse-docs --passes unindent-comments
To run the project simply run:
cargo run
Most methods and functions in this project are unit tested using the Rust included testing framework. To run the tests issue the following command in the project root (or in sub folder):
cargo test
The code styling for this project is following the Rust standard by the use of the RustFmt project. This provides an utility for automatically formatting the source code form the terminal by issuing the following command:
cargo fmt