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Random red pixel fix by MisterGoodDeal · Pull Request #943 · FastLED/FastLED

Hi there, I'm looking at this again and would like to get this old PR fix in. Overall it looks good and I have absolutely noticed bad color with the hue algorithm in many tests.

What I'm noticing here is that you missed a few places. Wanted to give you a chance to review before I proceed.

In src/colorutils.cpp I notice that there are four rainbow functions that each set the set hsv.sat = 240

Here is what I currently see with ripgrep:

image

1

void fill_rainbow( struct CRGB * targetArray, int numToFill,
                  uint8_t initialhue,
                  uint8_t deltahue )
{
    CHSV hsv;
    hsv.hue = initialhue;
    hsv.val = 255;
    hsv.sat = 240;
    for( int i = 0; i < numToFill; ++i) {
        targetArray[i] = hsv;
        hsv.hue += deltahue;
    }
}

2

void fill_rainbow( struct CHSV * targetArray, int numToFill,
                  uint8_t initialhue,
                  uint8_t deltahue )
{
    CHSV hsv;
    hsv.hue = initialhue;
    hsv.val = 255;
    hsv.sat = 240;
    for( int i = 0; i < numToFill; ++i) {
        targetArray[i] = hsv;
        hsv.hue += deltahue;
    }
}

3

void fill_rainbow_circular(struct CRGB* targetArray, int numToFill, uint8_t initialhue, bool reversed)
{
    if (numToFill == 0) return;  // avoiding div/0

    CHSV hsv;
    hsv.hue = initialhue;
    hsv.val = 255;
    hsv.sat = 240;

    const uint16_t hueChange = 65535 / (uint16_t)numToFill;  // hue change for each LED, * 256 for precision (256 * 256 - 1)
    uint16_t hueOffset = 0;  // offset for hue value, with precision (*256)

    for (int i = 0; i < numToFill; ++i) {
        targetArray[i] = hsv;
        if (reversed) hueOffset -= hueChange;
        else hueOffset += hueChange;
        hsv.hue = initialhue + (uint8_t)(hueOffset >> 8);  // assign new hue with precise offset (as 8-bit)
    }
}

4

void fill_rainbow_circular(struct CHSV* targetArray, int numToFill, uint8_t initialhue, bool reversed)
{
    if (numToFill == 0) return;  // avoiding div/0

    CHSV hsv;
    hsv.hue = initialhue;
    hsv.val = 255;
    hsv.sat = 240;

    const uint16_t hueChange = 65535 / (uint16_t) numToFill;  // hue change for each LED, * 256 for precision (256 * 256 - 1)
    uint16_t hueOffset = 0;  // offset for hue value, with precision (*256)

    for (int i = 0; i < numToFill; ++i) {
        targetArray[i] = hsv;
        if (reversed) hueOffset -= hueChange;
        else hueOffset += hueChange;
        hsv.hue = initialhue + (uint8_t)(hueOffset >> 8);  // assign new hue with precise offset (as 8-bit)
    }
}