Merge branch '113_misc_example' into 'master'

113 misc example

See merge request flatland/flatland!116

examples/misc/generate_video/video_generation.md

+# Making Videos from Env
+
+In order to generate Videos or gifs, it is easiest to generate image files and then run ffmpeg to generate a video.
+
+## 1. Generating Images from Env
+
+Start by importing the render and instantiating it
+
+```
+from flatland.utils.rendertools import RenderTool
+env_renderer = RenderTool(env, gl="PILSVG", )
+```
+
+If the environment changes don't forget to reset the renderer
+```
+env_renderer.reset()
+```
+
+You can now record an image after every step. It is best to use a format similar to the one below, where `frame_step` is counting the number of steps.
+```
+env_renderer.gl.save_image("./Images/Avoiding/flatland_frame_{:04d}.bmp".format(frame_step))
+```
+
+Once the images have been saved to the folder you can run a shell from that folder and run the following commands.
+
+Generate a mp4 out of the images:
+```
+ffmpeg -y -framerate 12 -i flatland_frame_%04d.bmp -hide_banner -c:v libx264 -pix_fmt yuv420p test.mp4
+```
+
+Generate a palette out of the video necessary to generate beautiful gifs:
+```
+ffmpeg  -i test.mp4 -filter_complex "[0:v] palettegen" palette.png
+```
+and finaly generate the gif
+```
+ffmpeg -i test.mp4 -i palette.png -filter_complex "[0:v][1:v] paletteuse" single_agent_navigation.gif
+```