Hungry Pixel (Rust edition)

I once used LÖVE to implement a simple game where a player control a pixel, eats other pixels and grow. This is my second attempt: in order to get familiar with Rust, SDL2 and to develop my game architecture (described later) I decided to implement a simple game.

Technologies used

I've decided to use Rust, along with rust-sdl2. I also use image and ttf features of rust-sdl2.

Building the game

Prerequisites

First of all, ensure that you have dev versions of sdl2, sdl2-image and sdl2-ttf. You should be able to obtain them either using your OS package manager or by downloading them from SDL2 site and then following instructions in INSTALL file. If you're on Windows you should add directory with .dll files to your PATH to run the built game.

Building the game

Next, clone the repository and run cargo build --release in it. You will need to move target/release/hungry-pixel-rs executable along with resources dir somewhere and then you'll be able to run it. As an alternative, you can use cargo run command to just run the dev build.

Linux users can run sh scripts/release.sh from repository root to create a .tar.gz archive with everything needed to play (including a shell-script run.sh).

Building under Windows

If you want to build the game under Windows, you will have to do the following steps:

1. Install Rust and Cargo (preferrable way to do so is to use rustup.rs)
2. Install MinGW (you will likely want to install MSYS as well) and make sure its bin directory is added to PATH.
3. Use rust-x86_64-pc-windows-stable (or the corresponding 32 bit version) as your target in rustup
4. Download MinGW dev libs from SDL2 site. You will need SDL2, SDL2_image and SDL2_ttf.
5. Unpack the archives downloaded in previous step, and put all .la and .a files from lib directory in archive to your rustup toolchain lib folder, e.g. C:\Users\<your username>\.rustup\toolchains\stable-x86_64-pc-windows-gnu\lib\rustlib\x86_64-pc-windows-gnu\lib
6. Put .dll files from the archives somewhere in your PATH (MinGW bin directory will do just fine) and also save them somewhere if your intention is to create a standalone executable archive.
7. Run MSYS prompt and put hungry-pixel-rs sources in your MSYS home directory (it is located within MinGW path)
8. Use cargo build --release to build the game, then copy resources and executable to target directory along with all the dll files.

You will likely need the latest MSVC redistributable which can be obtained via Windows Update or from Microsoft site.

Architectural overview

Game architecture is based on a notion of "States". A State is an entity that knows how to respond to Messages and how to render itself on screen. States are gathered into a stack of states that resides in the Engine entity. Engine also has a queue of Messages.

Inside the Engine, a loop is running:

1. First, the events from SDL are collected. Some of them are translated into Messages that are added to MessageQueue.
2. Then the rendering happens. All the states are analyzed, searching the first that returns true when is_fullscreen is called on it. Then they are rendered in the reverse order, from that state to the top of the stack.
3. Then, messages are propagated down the States stack. Every State in stack can either consume, transform or pass the message. Consuming happens when process_message fn returns None, and makes the Engine process next message right away. State can transform message by returning a Some(Message) variant of Option<Message> type from process_message fn, or pass it by returning the original message in Some variant. The message is then propagated to the next State in queue and passed to the process_message method of it.
4. When the message is either consumed or propagated all the way through the stack, it is processed by the Engine itself and next message is consumed.

Licensing information

The game is distributed under MIT license. Font used (PressStart2P-Regular.ttf) is distributed under OFL License.

Copyright (c) 2017 Crazy-Owl (https://github.com/Crazy-Owl)

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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