Bug report: shader code fails for dilate(), erode(), blur() on very old machines

[lee2sman]

Describe the bug
Received a bug report from someone running L5 on a 2009 Windows machine for the three more "advanced" shaders.

Example of what was removed in order to get code to work.

To Reproduce
All programs. Error on launch.

Expected behavior
Program should run, especially if it doesn't include filter() in the main.lua file.

Platform:

• Windows on Acer Aspire One (D255) with Atom N450 CPU
• L5 Version: 0.1.2

Additional context

Possible solutions

1. Rewrite those three shaders with older style/non-looping, etc
2. Possibly include a fallback implemented without shaders. This could be set by a flag when user runs the program, or automatically done if fallback code is included in example program, or a no-op for the filter if it fails. Will need feedback from community if we go this route.

[lee2sman]

Tested on 2014 retina Macbook Pro - macOS Big Sur version 11.7.10 - no problems. Works fine. (i5, 8GB, Intel Iris GPU)