64x64x16colours (Sweetie16) PixelArt with Pixelorama “β-karoten – We know whom will be eat”

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β-karoten - We know whom will be eat

I participated to the LoveByte Battleground demoparty> that runned this week-end, by posting a drawing last week. Sadly/funnily , there was few mistake ^^:
* I made a 64×64 pixels picture instead of a 128×128 one. The palette for the competition was 16 colours Sweetie16 (the default one on FOSS, TIC-80 fantasy console (Source code)).
* My second mistake is I’ve uploaded a first version, and few hours later another one using (FOSS) source code) on Debian on (FOSH) RISC−V (Specifications, there are lot of free or not implementations) emulator of FOSS Qemu (Source code, Git instance), the first upload worked fine but the second one didn’t work (maybe because my installation of Netsurf doesn’t manage javascript)^^. I also performed in a livecoding match (256 bytes and 25 minutes limits). Result of my poor production, Commented Live coding session record.

This is made with FOSS Pixelorama (Source code), itself made on FOSS Godot game engine (Source code). I use FOSS Arch Linux OS. Also made a ArchLinux AUR package pixelorama-git after pixelorama package (for git version, I would like to use v0.9, still not out, only v0.8 was available). There are pixelorama package (last stable, compiling from source), and pixelorama-bin package (from developers binary tarball). Pixelorama is a Pixel art picture and animation editor. I believe I discovered Pixelorama thanks to blog Librearts.org.

The name is “β-karoten – We know whom will be eat”.

Pixelorama editor screenshot
Screenshot of Pixelorama

Telegram, Lottie animated stickers, Python and Glaxnimate

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Table of Content

* Introduction
* A good workflow
* Publication on the web (SVG)
* Telegram Bot

Introduction


I’m a fan of Telegram chat application interface. If the sever is closed source, desktop and mobile applications are open sources, the interface is very well designed and thinked, intuitive, relativly light and full of interesting functionnalities, compared to other applications of this kind. It could be good to patch to have a Jabber/XMPP compatibility. It is the first, as far I know, to use Lottie, since Jully 2019 (and the bot API that goes with it), an animated vector format that I dreamd of for decades, that become an de facto open standard. Animations of this page have been created with Glaxnimate, a tool to make Lottie format animations, as main goal, but that can also be used to export SVG animation. The authors of Lottie published some JavaScript for the World Wide Web, Samsung, made a free and open source rlottie C++ library, as well as WASM version, that allow to play them and has binding for several programming languages. Qt has an included Lottie reader, and there are several tools to create them.


The multiplatofmr free software Glaxnimate allow to make them with a Graphical User Interface, familiar with people creating animation on computers. His main author also made a Python library, python-lottie (AUR: python-lottie-git, pip: Lottie), that allow procedural generation of them. Both alow to convert them to several formats (export animated SVG, Lottie JSON, HTML page all ready, Telegram, mpeg4, PNG, wepb, gif, and I probably forgot some other), and as input to vectorize animated gif, etc… The 2D vector animation Synfig also have a Lottie exporter, but also Blender3D, a plugin made by Glaxnimate author (distributed with python-lottie) for this last one. There are so several choices to create them.


Glaxnimate allow to easily create animations in Lottie format, including .TGS, a version with more limited specifications and gzip compressed for Telegram. This format is more compact but has some constraints, that didn’t stop some artists to make very great artworks since 2 years:
* 512×512 pixels
* 3 secondes
* 64 KB by animated sticker..
* Animated stickers can be grouped in a sticker pack corresponding to several expressions (like emoticons/emoji).

Why for 512×512 pixels with a vector format? Telegram client application render the animation in this dimension. This dimension is already big for some mobile screens. This vector format allow to reduce bandwidth usage and to have a high quality animation (generaly computed by the GPU, SVG accelerators was already in Nokia and Symbian made phones in 2000s). WeChat/微信 choose animated GIF about one decade ago. GIF are probably converted in MPEG nowaday? The instant messaging Discord, populare in Far West, also use the Lottie format since Jully 2021, following Telegram after 2 years.


As a refecence, top of this page animation is:
* 1109 bytes (1,1 KB) in TGS (binary compressed Telegram format)
* 4682 bytes (4.5 KB) in JSON uglified (no more indentation, or carriage return)
* 508054 bytes (500 KB) in WebP
* 9710 bytes (9.6 KB) in animated SVG (there was an useless animated path, I don’t know why for).
* 1804 bytes (1.7 KB) in ainmated SVGZ (gzip compressed SVG). It is more interesting today to let the server compress using Brotli format (Nginx, Apache) or to precompress them (.br). It is really well supported by web browsers
* 6114 bytes (6.1 KB) in SVG, Inkscape optimised compressed (based on Scour)), it’s possible to reduce size more. Today if the option to reduce digits after comma (floats) is less than 3, it will be still kept at 3 digits. In animation parts still not managed there are six 0 (1.000000 or 0.000000 for example). It is still possible to optimize by hand until thes options are added (See sed usage, below), so :
* 5827 bytes (5.8 KB) in SVG, a bit hand finished.
* 5559 bytes (5.5 KB) by removing some useless intermediate groups (warning to don’t break all, try group by group) and replacing numbers like 1.0 by 1


One of the main problems of optimized SVG output from Glaxnimate is that Lottie heavily use groups, where SVG allow to made most of these operation in the objects themselves. So transformation matrix are all in groups containing the objects, instead of in objects themselves. you can see at right the XML source inf Inkscape. This still ask lot of handcrafted work on files nowaday. It should be possible to improve it.

It looks like there are more efficient methods withSVGO, but based on Node.js, and it breaks animations, some of its optimisation methods could be used in python one. I don’t like Node at all due to bad habits of lot of devs around Node. The Inkscape plugin, “inkscape-svgo” is still in this spirit, if we try to compile it with included Makefile, it doesn’t test if Nodes modules are already installed but forcee download Node JS version 11 (and x86_64 only, so not multi-architecture), and recompile all the dependenccies. So one more time with Node, we wast lot of earth limited resources, wit an extention of tens of Megabytes (75 MB, where Inkscape is 145 MB and the Node SVGO library itself is only 5 MB), where it should only be few KB.

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Lua, TIC-80, LÖVE,etc: Introduction to particles systems and games

Version en français ici
default code in TIC-80

A good language for easily developing games, interactive content and procedural art is Lua scripting language. This is a simple functional language with some limited oriented object language features. It is, due to its simplicity and bytecode compiling at start by default, one of the lightest and fastest script language. Some integrations like LÖVE media/games engine and API (very powerful), and TIC-80, that is more limited fantasy-computer inspired first by PICO-8 (also use Lua). They allow quick prototyping, for a final product in the same language or a later port in another language. Lua is also used as plug-in systems language, in lot of games, and tools, including desktop applications (like Blender), web application (like MediaWiki behind Wikimedia) or embedded world. In this domain, popular and open-source drone board control BetaFlight or Open-TX open source radio-command for commands like Taranis one. There is a complete online documentation of Lua on the official website. It is possible to embbed C libs/function in Lua programs with libffi. It as been created first for Python, CFFI, and there is FFI support for PHP too now. It also possible to embed Lua scripts in C program. I also just discovered when I wrote this article (thanks to the author of TIC-80, that there is also PicoC, a simple C language interpreter that so allow to control more finely/low level data structures. The binary size is about the same than Lua interpreter.

An interactive demo of how trigonometric functions workSo, after few years of looking time to time this language and tools, I started to play a bit more in end of 2020, and in few month I can said I made lot of progress in real-time programming. Doing and even finishing light games. I Needed to study again basic trigonometry (follow link for a simple interactive explanation), basic vector algebra and few other mathematics fun things, that I personally consider like puzzles games.

Banner of Falacy Gorx, pseudo 3d game, using lot of tables
I also wrote a short making-off article on itch.io in march, 2021, during a game jam competition (instead of coding ^^). All of this motive me to write more articles tutorials about real-time/vector and procedural generation programming. I will try to write a series explaining methods I used. I will try to keep it as simple as possible to everyone, but some basic knowledge in general programming and mathematics could help a lot in this field as in life in general.

So I start with a short introduction about what I use the most in my development, arrays of elements and some randomness:
* Tables and their common basic management related to animation logic
* Creating a table
* Procedural generation of the content of a table
* A simple example for cleaning a table
* Variation and cleaning of table depending on tests
* Compacting code a bit
* Procedural generation of the content of a table
* Simple graphic particle system example

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Android without Google and GNU/Linux with APK

Content

* GNU/Linux on your phone now
* GNU/Linux with Android APK compatibility layer
* Managing APK of a device
** Listing APK installed on the device
** Dumping an APK installed on the device
** Installing an APK onto the device from the computer
** Removing closed source spywares from your current Android system as a transition phase

Android will move from Linux kernel and open specs APK format to a more closed package format and to their closed source Fuschia kernel going away from Free Open Source software (FOSS) that make Google, Android, ChromeOS grow, but also that are used on most of the internet servers, on most of supercomputer in the world, on most spacecrafts, on most internet boxes, TVboxes, etc…

You can easily remove any package of your Android device, ever without root access, using adb from your computer (see full article for more details):

adb shell pm list packages
adb shell pm uninstall --user 0 com.google.android.gm

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Linux syscall and RISC-V assembly

Sample of RISC-V assembly code

Syscall in Linux kernel, is an interface to access to kernel basic functions. They are described in section 2 of man pages. The introduction is in man 2 syscall (indirect system call), and the list of functions are described in man 2 syscalls. Update: System Calls in lectures of official Linux kernel documentation including “Linux system calls implementation”, “VDSO and virtual syscalls” and “Accessing user space from system calls”

This article follow previous one about RISC-V overall progress and available tools to play with, I will try to make a short article here about Linux syscall usage and the RISC-V assembly case.

Table of Content

* Description section of the man page
* Getting the list of function and how to access them
* Passing parameters
* Function number and registers of return values
* Return values and error code
* Compiling and executing on virtual environment
* Update: Bronzebeard assembler and its baremetal environment for real hardware

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