[Bug] rgb matrix Digital rain ignores RGB_MATRIX_MAXIMUM_BRIGHTNESS

[KoenGoe]

The digital rain rgb matrix animation has its own hardcoded constants for maximum brightness, instead of using RGB_MATRIX_MAXIMUM_BRIGHTNESS, nor is checked it in rgb_matrix_set_color that it calls.
So it is checked nowhere, and leds are just set at brightnesses over the maximum set by RGB_MATRIX_MAXIMUM_BRIGHTNESS, which is potentially dangerous as it can lead to too much current drawn from the USB port.

qmk doctor output:

Ψ QMK Doctor is checking your environment.
Ψ CLI version: 1.0.0
Ψ QMK home: D:/koeng/Documents/keyboard/qmk
Ψ Detected Windows 10 (10.0.19044).
Ψ Git branch: master
Ψ Repo version: 0.15.23
⚠ Git has unstashed/uncommitted changes.
Ψ All dependencies are installed.
Ψ Found arm-none-eabi-gcc version 10.1.0
Ψ Found avr-gcc version 8.4.0
Ψ Found avrdude version 6.3
Ψ Found dfu-util version 0.11
Ψ Found dfu-programmer version 0.7.2
Ψ Submodules are up to date.
Ψ QMK is ready to go, but minor problems were found

[drashna]

Can confirm. Not sure there is an easy way to fix this, but this line may be what needs to be modified:

qmk_firmware/quantum/rgb_matrix/animations/digital_rain_anim.h

Line 15 in 7eb6f86

const uint8_t max_intensity = 0xff;

setting that to the current val instead of 0xFF may work, but the other colors may not be correct. In fact, they may need to be calculated at run time.

[KoenGoe]

Yeah I tried these settings:

    const uint8_t pure_green_intensity = RGB_MATRIX_MAXIMUM_BRIGHTNESS*3/4;
    const uint8_t max_brightness_boost = RGB_MATRIX_MAXIMUM_BRIGHTNESS*3/4;
    const uint8_t max_intensity        = RGB_MATRIX_MAXIMUM_BRIGHTNESS;

So that the constants have about the same ratio as originally.
While this kept the brightness under RGB_MATRIX_MAXIMUM_BRIGHTNESS is still has two issues:

• it's ignoring the current val. At least it's an electrically safe setting now, but of course it would be better if the effect brightness followed the val as well
• The decay rate is 1 (--) per update and should be slowed down inversely proportional to max_intensity.