pixelperfectengine 0.11.0-alpha

PixelPerfectEngine

A retro engine for 2D and pseudo-3D games written in D by László Szerémi.

Started out as a project for college, and continued as a hobby to learn game and software development. Has its own GUI subsystem, which is influenced by the looks of old graphical operating systems' (Amiga Workbench, old MacOS, etc.).

Why use PixelPerfectEngine over the competition?

Authentic pixel graphics

I was looking for a project idea to present something for Object-Oriented Programming exams, that would be doable by a single person, yet fun enough to keep me occupied to work on it. While I underestimated the complexity and the work that should go into an engine (especially as a rookie), I noticed a few odd things about 2D retro games. As modern engines often use 3D polygons for sprites, there are often many errors:

• Rounding errors from floating-point coordinates.
• Unauthentic scaling and rotation effects due to direct rendering on high-resolution framebuffers.
• Ability of use of sprites and textures with baked-in big pixels, which lead to misaligned pixels.

In order to mitigate these issues, the engine uses CPU or GPU (coming in the future) blitter, like some old systems did back in the days, such as the Amiga. However the engine also can do some of the tricks of later 2D machines like per-index transparency, and you can create various effects like light, fog, and reflections, by using custom layers or even the EffectLayer (coming in the future). You also don't need any trickery for palette-swap effects.

Small footprint and lightweight

Some other, popular engines used for 2D retro games are 3D engines that are made to display 2D graphics instead. This often adds additional bulk onto an otherwise small game.

This lightweight nature of the engine will soon enable to be compiled for low-powered ARMv8 devices, which will allow to be run on many smartphones and even single-board computers.

Open-source without the hassle

This engine is licensed under the Boost Software License 1.0, which means it can be used without attribution and even in commercial applications, without any associated fees (licensing fee, per-install fee, etc.). Be aware that many components are on different licenses, such as SDL2 and ZLib.

How to build

PixelPerfectEngine actually requires ldc2 to build since that has better vector support than DMD, and vectors are used to speed up the rendering.

To compile windowmakerforconcrete, launch a simple :

dub build :wmfc --compiler=ldc2

Test cases, demos, and tools

PixelPerfectEngine comes with multiple test cases, both to test various functionalities during development, and to showcase the capabilities of the engine.

test0

Displays an automatically generated tilemap pattern on two layers (one is transformable) and multiple sprites (art by arkark3). There's also a semi transparent text-layer displaying the framerate and collision information. This all can be controlled from the keyboard.

test1

Audio testcase. Tests audio initialization and plugins, also intended as part of an audio development kit (ADK). In the future, it'll also be able to play MIDI files.

test2

Map format testcase. Tests most functionality of the Extendible Map Format (XMF). Can load any XMP files.

test3

GUI elements testcase. Tests if GUI elements work correctly.

test4

Test of the scripting engine.

test5

Test of the XML text parsing engine and the text drawing functions.

snake

A simple engine demonstration game. Does not use (much) external assets, and instead uses code renerated ones.

The classic game of Snake, where the player must collect apples (red dots) in order to grow.

icebreaker

Arkanoid-clone game. Currently under development.

Windowmaker for Concrete/PPE

Window layout editor with code generation features. (Dub package name is wmfc, to avoid issues from too long paths under Windows)

PixelPerfectEditor

External project. Map editor, with some other tools built in, like a BMFont editor, and format converter. Can be found here: https://github.com/ZILtoid1991/pixelperfecteditor

A must-have for this engine, due to it using some unusual features, like palette shifting.

Features

• Pixel-accurate retro graphics.
• Either hard-transparency using blitter, or soft-transparency using alpha-blending.
• Various effects with other composing functions.
• A tile layer that is capable of displaying uniform tiles from a map, and has per-line scrolling via a delegate.
• A transformable tile layer capable of Mode7 type effects at the cost of power-of-two only tile and map sizes.
• A sprite layer with sprite scaling, simple slicing, and individual composing functions for each sprite.
• GUI
• Configuration file handling
• Collision detection
• Handling of multiple inputs
• An audio subsystem capable of era-correct synthesis
• Scripting via Lua (more languages might be added by others)
• ...and many more

Known issues:

• The engine doesn't clear the framebuffer to spare some CPU time. This can result in rapid flickering if the bottom layer is scrolled out. To avoid it at all cost, you can use a warp mode on that layer.
• There's also some speed issues as SDL2 writes the framebuffer back to the main memory. This will probably end up in the slow replacement of SDL2's graphical side with something faster.
• WindowMakerForConcrete and PixelPerfectEditor are currently unfinished. The former will be soon working fully with extra features (such as undo/redo, snapping to grid and components), then the latter can be developed without an issue.
• Error handling isn't fully realized, so a lot of errors might happen. You can help me by reporting errors, testing on various systems.
• Lots of untested and not fully tested features. Many are tested to at least run somewhat, but not tested in-depth. Currently, I'm the sole maintainer of this project, and things are quite tough, especially after you factor in my full-time job.
• As of now, your executable must be in the folder ./bin-[cpuarch]-[OS], but it'll change likely by v1.0.0, since certain companies (console manufacturers, phone OS suppliers, etc.) would like me to put the executable into the root folder, and likely to group together all the asset folders into a bigger one.
• Due to hard to debug reasons, the scripting doesn't work as intended.

Future plans:

• Compressed data file handling.
• Moving most of the rendering pipeline to OpenGL, then using various tricks to ensure pixels will align as they should, and it will enable things like transformable sprites, some 3D objects, etc.
• Support for MacOS. (Contact me, if you have hardware for it and willing to contribute to the project)
• Support for Android. (Either will be done by me later on, or contact me if you're up for this challenge)
• Support for iOS. (Contact me if you have the hardware and you willing to contribute)