Dissolve/Dissolve Rnd with secondary color stopped working in 0.14

[TripleWhy]

What happened?

Dissolve doesn't do much when there is a background color set, that isn't black:
It will dissolve to to the background color, and keep all LEDs at the background color indefinitely.

To Reproduce Bug

0. Use WLED 0.14.
1. Select the Dissolve (or Dissolve Rnd) effect.
2. Chose a background color that isn't black.

Expected Behavior

Fills LEDs with primary in random order, then with background color, then repeats.

Install Method

Binary from WLED.me

What version of WLED?

WLED 0.14.0 (build 2310130)

Which microcontroller/board are you seeing the problem on?

ESP8266

Relevant log/trace output

No response

Anything else?

This worked in WLED 0.13.

Code of Conduct

• I agree to follow this project's Code of Conduct

[blazoncek]

It works as expected on my system.

[TripleWhy]

I played around some more, and it currently seems to me that:

• The issue doesn't exist on the ESP32, just the ESP8266.
• The issue only happens when the overall brightness is < 200.

[blazoncek]

Nope. Works on ESP32, ESP32-S2, SEP32-C3 and ESP8266.
Matrix or not. Brightness 200 or less, palette Default or any other. Fx and Bg any color. Random or not.

Must be something particular to your set-up. Have you tried "Global LED buffer"?

[TripleWhy]

Enabling that option does indeed fix this.

When I copy a configuration backup from my ESP8266 to my ESP32, I have to enable the option as well, otherwise I get the same issue.
However, when I erase the ESP32, re-flash the firmware, and try with a clean setup, I don't need the option. Strange, but I don't know if you consider that an issue or not.

[blazoncek]

So the problem is lossy getPixelColor(). Good to know.

[blazoncek]

The problem lies in this comparison: SEGMENT.getPixelColor(i) == SEGCOLOR(1) which may never be true if the global brightness (or even segment opacity) is not 255.

[blazoncek]

I think I have it sorted out.