public/subjects/road_intersection/README.md

## road_intersection

### Objectives

The objective for this raid is to create a traffic control strategy and represent it with an interface/UI.
It's up to you to decide which library and file system you want to use in order to create this simulation, but we recommend you to use the library [sdl2](https://docs.rs/sdl2/0.34.3/sdl2/)

### Instructions

#### **Environment and Rules**

You must create an environment which contains all the objects described in this section. You can display the objects as you wish.

1. Roads

There are various forms of intersections, let's focus on the widely seen four-lane crossroad. For simplicity, each road will have two lanes with two different directions for the total of two roads and four lanes.

```console
                  lane1     lane2

               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               | r  s  l |    ↑    |
_______________| ←  ↓  → |    ↑    |_____________
                         |         ↑ r
← ← ← ← ← ← ←            |         ← s ← ← ← ← ←      lane3
                         |         ↓ l
_________________________|_______________________
           l ↑           |
 → → → → → s →           |           → → → → → →      lane4
           r ↓           |
_______________          |          _____________
               |         | ←  ↑  → |
               |    ↓    | l  s  r |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
               |    ↓    |    ↑    |
```

For clarification reasons we will assume that a lane can have three different routes (consider that you are in the vehicle position):

- `r`, turning right
- `s`, straight ahead
- `l`, turning left

2. Traffic lights

Traffic lights are signalize devices positioned at road intersections that follows an universal color code,
it's usually green, red and amber, but for this project you will just use the colors **red** and **green**.

You will then have to create some kind of representation for the traffic lights and distribute them for each lane in the intersection.

You are free to decide what algorithm you want to implement to represent traffic light system, but keep in mind that traffic congestion should not be too high (8 or more vehicles).

3. Vehicles

```
  ______
 /|_||_\`.__
=`-(_)--(_)-'
```

Vehicles must obey this rules:

- Vehicles must have a color so that it's possible to identify which route it will follow (ex:`r`- purple, `s`- Blue and `l`- Yellow). This information about the colors must be given to the auditor of the raid. The colors are up to you to decide.

- Autonomous vehicles driving on a lane with a **given route** must follow the direction of that route, it is not possible for the autonomous vehicle to change lanes or routes.

- Each vehicle must have a fixed velocity.

- A safety distance from other vehicles must be kept, if one vehicle stop the other vehicle that's
  behind him must stop and keep it's distance.

- Vehicles must stop if the traffic light is red and proceed otherwise.

- Vehicles must have different routes, either `r`, `s` or `l`.

- Other vehicles such as emergency vehicles are not considered.

---

#### **Commands**

The generating of vehicles must be done using the keyboard event. You must be able to generate
vehicles in different lanes and with different routes.

For this it must be possible to do the following:

- The `Arrow` keys must generate one vehicle in a specific direction and with a random route ( `r`, `s` and `l`):

  - `Up` south to north.
  - `Down` north to south.
  - `Right` west to east.
  - `Left` east to west.

- The `R` key must generate random vehicles with random lanes and routes.

- The `Esc` key must finish the simulation.

> Arrow keys must not let the user spam the creation of vehicles, they must be created with a safe distance between them.

> A safe distance is any distance that allows the vehicles not to crash into each other.

### Example

You can see an example for the road_intersection [here](https://www.youtube.com/watch?v=6B0-ZBET6mo).

### Bonus

You can implement the following optional features:

- Vehicle and traffic lights animation and image rendering. You can find some cool assets:

  - [limezu](https://limezu.itch.io/)
  - [finalbossblue](http://finalbossblues.com/timefantasy/free-graphics/).
  - [mobilegamegraphics](https://mobilegamegraphics.com/product-category/all_products/freestuff/).
  - [spriters-resource](https://www.spriters-resource.com/).

### Notions

- https://docs.rs/sdl2/0.34.3/sdl2/