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README.md

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Introduction

This app draws animated graph using input data. The process of animation drawing can be influenced by various parameters. See included man pages man -l ./draw_man.1 for further info.

See exmaple output

Project structure

graph_animation
+-- lib/
    +-- draw_lib.pm  module with functions definitions
+-- tests/           example input and configuration
    +-- conf/
    +-- data/
+-- output/          example output sin(x)
    +-- out_4/*.mp4
+-- draw_man.1       man page; user manual
+-- draw.pl          main file
+-- test.sh          run script

Animation

Input data (local file or URL) will be divided into parts, which results into multiple starting points in animation. Count of this starting points is defined using argument --EffectParam "split=n"* (let n be nonnegative integer, if n equals 0 graph will be continuous from beginning). Another interesting setup is --EffectParam "reverse=1", which reverse direction of animation.

Logical structure

Code is well self-documented.

  1. Read input arguments

    • Module Getopt::Long loads command line arguments.
    • If config file is specified, its key-value pairs will be loaded into hash structure. That could override default settings. load_conf_file($opts{'configfile'})
    • Both input arguments will be merged. Default setup has the lowest priority, cmd args have highest. merge_opts(%opts)

  2. Prepare data source

    • Data from URL (if specified) are downloaded into local file, merged with specified local files (if any) and sorted into chronological order. During merging global maxima and minima are found, together with row count. merge_args(@ARGV, $opts{'timeformat'})
    • Value splitCnt specifies number of starting points. E.g. if splitCnt = n, dataset will be divided into 2n sets. split_file($dataFile, $lineCnt, $splitCnt)
    • According to reverse parameter, either odd-indexed or even-indexed sets are inverted, so it creates desired animation effect. reverse_file

  3. Compute speed, fps and time

    • speed = #lines / (splitCnt * time * fps)
    • If time is set, default fps is used and speed is computed.
    • All possible combinations are allowed.

  4. Run gnuplot and create animation from its output

    • ffmpeg -y -framerate $fps -i $tmpDir/out_%0${n}d.png $outDir/anim.mp4
    • If ending was specified, last frame of video is freezed for n seconds