Tag Archives: Animation

Some tries with LÖVE game engine in Lua

* Ce billet est également disponible en français.

Drawn with Pencil2D and MyPaint, animated using meshes in LÖVE (Lua language), I also made some tests in C with libSDL, but it is probably faster to prototype in Lua with LÖVE, and then add FFI libs for compute intensive part (in these cases light computations, GL is used for rendering), or port it to c+SDL at second time, when algorithms are validated. All used software are 100% FOSS used on a GNU/Linux system.

This one use simply a mesh on a picture, and deform them using circular motions, as I done in TIC-80 in July 2021.

The picture used for the mesh:

A modified version, with fixed hard skull, I keep both version, this one is interesting for anthropomorphic head, the other for more realistic invertebrate.

This test gather different tests with shaders. I apply a threeshold, above is one colour under, is another, this allow to have interesting clean 2 colours effects Source code of these shaders for LÖVE is available on Framagit (demo01.love file on this site).

This other one also use a mesh on a picture with 2 steps, swapping from one to each other moving the drawing shape, but instead, of deforming it by sin(), it curve the mesh, by adding curvature at each step, and a little sinus wave to simulate something that goes through the body.

the liquid the the monster reject, is a texture, that is copied to a Canvas, to wrap it and loop it, This part was inspired by the game “Conan Chop Chop”. But I fine tuned a bit: A shader is then applied on the canvas when drawing on screen surface, it scale the pixels along the path of the liquid, and add a light waving motion. the splash at the end is a cycle between 3 pictures.

The quickly drawn 2 steps monster, it could be optimized on disk by creating the duplication of the body after loading, LÖVE is not convenient as libSDL for textures mesh:
bidule spritesheet

The picture used as texture for for the shader:
flux de vomit intense

The splash at the end, each part are displayed sequentially in loop, this was animated with Pencil2D (MyPaint branch):
Eclaboussure de vomit

The animation is first made with Pencil2D, then saved with one picture (PNG with transparency) by frame, and then ImageMagick package, “montage” is used to build the spritesheet the following wy:

montage sprite0001.png sprite0006.png sprite0010.png -tile 3x1 -geometry 64x128 spritesheet.png

Using about the same methods, I then improved my code to manage a more generic way, hand drawn animation made with Pencil2d as mesh. Here is an animated sketch of flower opening, as proof of concept.

Blooming flower

Update of march 19:

It uses 8 frames, with various framerates, managed in a table, is here the frame number table:

table = {1,1,2,2,2,3,3,4,4,4,5,5,6,6,7,8,8,8,8,8}

I can then cycle easily in the table using math.floor( (time()*fps) % #table), or just parse it one time for exemple here for a flower that just open one time.

I then used it as decoration element. Now it work, I can refine animation, still make it more generic to have only to add minimum information, and be able to add quickly new animations.

After the good result of the first test of the animation with program, I cleaned a little the flower and added some colours. I then noticed than the last frame, where the flower move is stabilized missed. The picture before the last was duplicated as 2 last frames in my spritesheet. Anyway, I need to remove some useless space around the flower, separate stem and flower itself to reduce memory usage; It already take, reduced in 128×128 pixels 180~200 Ko (150 Ko compressed better with zopflipng). This is too fat, if you multiply this by the number of objects/characters you can quickly reach tens of MB (png compressed) on disk, and far more on Graphics RAM, saturating ram, cache and bandwidth, and so slowing down rendering. I believe that separate flower and keeping in a something like 64×64 pixels animation could be fine the stem could be a flat texture, blended by procedural means.

Fleur qui s'ouvre améliorée

”’Update may 2022 ”’
* You can test all of this, from the sources available at https://framagit.org/popolon/reforest.
* Ready last version LÖVE files and archives are available at the address https://framagit.org/popolon/reforest/-/releases (version 0.2 from this site).

Reforest 0.2 Screenshot

Telegram, Lottie animated stickers, Python and Glaxnimate

→ Version en français ici

Table of Content

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


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.

A good workflow

* Create object with Inkscape
* Animate it with Glaxnimate
* Export it in SVG format (don’t forget to also save a Glaxnimate format file)
* Open the new file with Inkscape to clean it (extract some groups that are not needed
* Export to optimized output
* Finish by hand.

For the last part there are 2 solution for have an automated one:
* Patch Inkscape optimized output.
* Do a second path optimizer.

Some space can be saved with :

sed s/1.00000/1/g <input.svg | sed s/0.00000/0/g | sed 's/0000;/;/g' >output.svg

One or two digit precision (instead of 3 or 4 today with Scour)), should be good enough.

SVGcleaner is better than Scour in several cases, but itdoesn’t support animations and don’t want to (it’s complex to manage, can easily become a nightmare).

Publication on the web (SVG)

So as I just said, as animated SVG is really more easy to integrate in a web page, after lot of tries with Lottie, I finnaly choose this option. The best is to not compress with SVGZ, but to optimizer the SVG file then to compress with Brotli (.br) and maybe to have a gzip version beside for oldest web browsers.

Its integration in a web page is really simple, it can be done as other pictures format with image:

<img src="/chemin/du/fichier_animation.svg" align="right" width="200" height="250">

That’s what I done in this page, every browser automatically manage them.

Note : It could be interesting to integrate it inline to manipulate an easier way with Javascript. For simple animated illustration, maybe just animated/zoomed/rotated object, without inside details modifications, image is perfect.

For compressing I use the max compression, here is a simple method to compress all files of a single directory beside their uncompressed version:

ls --ignore=*.gz --ignore=*.br | while read file
 brotli -q 11 -c <"${file}" >"${file}".br
 gzip -9 -c <"${file}" >"${file}".gz

* 5559 murphy_anim0.animoptiv5.svg
* 1303 murphy_anim0.animoptiv5.svg.br
* 1543 murphy_anim0.animoptiv5.svg.gz
* 4682 murphy.json
* 976 murphy.json.br
* 1149 murphy.json.gz

To force loading one of the 2 files format, if it is supported by borwer (I mean if it supports both), Brotli (.br) will be used, with Nginx (after compiled it with the Brotli patch, rules in the Nignx configuration files are realy simples:

brotli_static on;
gzip_static on;

With Apache, Brotli is here by default in versions 2.4, but it’s a bit harder to manage.

To test their support, Curl can be used:

curl -I -H 'Accept-Encoding: gzip, deflate, br' https://host.net/fichier.svg

If brotli is really activated, you will receive the following line in the answer:

content-encoding: br

Telegram Bot

The Python-Lottie library come just right for me, I would like to study Python, including for micropython, used in embedded world and for my work of System and Network administrator, where it is more and more used, replacing step by step Perl, and with some tools like Ansible an automation paltform used to manage computer farms, as well as more and more other basic system tools. After about one year of experience with procedural generation in Lua give me some willing to do this with other languages too (I’m currently preparing a suprise for soon). There are several bot libraries for Telegram in Python, including Python Telegram Bot, that follow well the official Telegram API, and Telethon (Documentation) that allow to communiatte directly in MTproto, the Telegram protocole, instead of using HTTP layer. This reduce one layer and allow a more fine control of exchanges. You can read here about the differences between Bot API (HTTP vs MT Proto).

There are still not too much examples with Python’s Telegram bot, that I started with, but by digging a bit in documentation, it is possible to find what’s needed. By mixing Python-Lottie for procedural generation, Glaxnimate for hand made animation, and the bot there is some interesting possibilities that open. I so made a first Python-Telegram-Bot bot. After some exchanges with Glax, the author of Glaxnimate, he let me know the Telethon Python module, that it uses for its bot, that has some similarities with what I want. It’s called Glaxcomm, and generate Lottie/TGS on the fly. I hope I will manage (time+willing) to rebuild my bot with this module and I hope I can get it where I want it. My next goal would be to be able to use it with other protocols, including ActivityPub (W3C specifications).

Glax made a good set of basic procedural generation examples that greatly help to understand it’s usage, a good documantation about Lottie format, stickers scripts examples.

I started by make a simple bot from python-telegram-bot library examples, but complete explanation about how to use file_id was missing (and I didn’t found them around the net). This is the methode Telegram promote to to send file, by it’s Id instead of sending several times the same file. The file_id is given by Telegram when a file is sent. So ideal method is to keep the ID of already succefuly sent files in a database or a file on the disk. This example create a file containing the ID beside image file, this is probably a bit better to have thei ID in a database (SQL or TOML) :

if os.path.exists(idfile):
  fid = open(idfile)
  stickid = fid.read()
  msg = update.message.reply_sticker(stickid)
  msg = update.message.reply_sticker(open(stickfile, 'rb'))
  fid = open(idfile, 'w')