Trying some basic programming using the basicFusion app/website
Using the built-in Spriteshop and retro font editor
Run and view the code using this link:
https://basicfusion.org/index.html?open=cloud/2d186f43
A still image from the animation:
The code: tube.bf
This program uses an external image file which is loaded via an url, can also be a local path.
The animation of lava and clouds uses a nearly transparent black overlay which is applied every couple of frames. It gradually fades old image content to black.
This cloud link should allow to run/view the code
https://basicfusion.org/index.html?open=cloud/73dd2614
The code:
A still image from the animation:
This is based on lines drawn between points on a circle but the points are displaced on the circle so that the distance between 2 successive points varies. Then I only draw some lines based on a MOD function for extra effect.
This cloud link should allow to run/view the code
https://basicfusion.org/index.html?open=cloud/6638f7f2
The code:
A still image from the animation:


