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If you wish to make an animation in your document, see the [[Animation]] page. This page will explain how to use [[MetaFun_-_MetaPost_in_ConTeXt|MetaFun]] to create a mp4 movie. Such movie can be embedded in a presentation, put on YouTube, etc, this will be a real movie !

This tutorial will be to design and animate a movie showing particles moving along circles. The different images needed for the animation will be pages from the same PDF. The general structure of the code is as follows:

An ''MPpage'' has the size of the bounding box of all combined objects on the current page, so if objects move within the page, the page size will change. A solution to maintain control is to introduce a frame, which we can visualize as a camera frame. In the following, we refer to this frame as `TheFrame`. We can keep this frame fixed while subjects move within it, or we can keep subjects steady and move the frame, or even do both! In fact, if we think of a real camera, this is exactly the same concept. Let's consider a fixed square frame here, called `TheFrame`:

will convert the 300 pages of `myfile.pdf` to 300 images named `p_000.jpg`, `p_001.jpg`, ..., `p_299.jpg`. The next step is to assemble the images into a movie, which is done with the free ``''ffmpeg`` '' (https://ffmpeg.org) tool. The command

will assemble the JPG files at a framerate of 30 images per second (option \type{`-r 30}`) into a QuickTime MP4 movie named \type{''myMovie.mp4}''.

For an overview, here's the complete script for a Unix-like system. After producing the PDF with Context (line 1), we create a temporary folder named \type{`JPGdir} ` (line 2), convert the PDF to a series of JPG images in the created folder (line 3), create a QuickTime MP4 movie from the JPG images (lines 4-5), clean up (line 6), and finally, open the movie (line 7) :

A note about the definition of the picture: although the conversion from PDF to JPG could be made at any resolution with ImageMagick, the default density is 72 dpi. This means that if the size of the PDF page is 15 inches by 15 inches (equivalent to 1080 pixels by 1080 pixels, or 38.1 cm by 38.1 cm at a definition of 72 dpi), the resulting image will also be 1080 pixels by 1080 pixels. Therefore, if the intention is to create a UHD video, add the following line at the end of the code (line 18before the `\stopMPpage`):

Let's make things more interesting by adding more moving elements, says a lot of particles moving along several circles in a random fashion. If the positions of the animated objects are deterministic, such as a function of time (`{f(time)`) as shown in our first example, there is no difficulty in calculating the positions and drawing the object at these positions, something like:

On each circle ''c'' (`c=1,...,nbcircles`), we will define some objects ''o'' (`o=1,...,nbObjects[c]`) (called sometimes particles here), so the total number of objects is `O = nbObjects[1] + nbObjects[2]+...+nbObjects[nbcircles]`. Each object ''o'' on circle ''c'' will have at time ''t'' the position `Position[c][o][t]`. This position, express as a number in [0,1] is a coordinate along the path `ThePath[c]`. The position at time 1 is chosen randomly along the path ''c'' (line 13), and then will be calculated for each time ''t'' from the position at time ''t-1'' (line 18). Each object will have its own `deplacement`, which depends on the length of the circle modified by random factor (line 14). Lastly, to distinguish easily particles in the following figures, we will assign a random color to each one (line 16): `TheColor[c][o]`

and == Showcase of the finished project == We can make things more interesting by adding a lot of particles, having a moving frame, add some music,..., and increase the definition : to 2160x2160 (you can go full-screen!) :  

[[File:Project1-C2-2160.mp4|500px]] <!--  We can also play with the timing of the animation (code not shown) : [[File:Project1-B-Slow.mp4|500px]] Here are some littles hand drawn houses (code not shown) (p2B):[[File:Project2-B.mp4|300px]] Here are some littles hand drawn houses (code not shown)(p2B2):[[File:Project2-B2.mp4|500px]]

[[File:Project2-B2.mp4]]<!-- == Temporary ==[[File:Project2-AB.mp4|300px]] -->

Project1-C2-2160 : [[File:Project1-C2-2160.mp4|200px]]Project3-C : [[File:Project3-C.mp4|200px]]Project3-B : [[File:Project3-B.mp4|200px]]<!Project2-B2: [[File:Project2-B2.mp4|200px]]Project2- A : [[File:Project3Project2-A.mp4|200px]]Project1-C2-1080 : [[File:Project1-C2-1080.mp4|200px]]Project1-B: [[File:Project1-B.mp4|200px]]Project1-B-Slow: [[File:Project1-B-Slow.mp4|200px]] Project1-A : [[File:Project1-A.mp4|200px]] -->