From 7c121b8ba6aa157f16c1bf730ca0d8ab171fd33b Mon Sep 17 00:00:00 2001
From: Blaz Kristan <blaz@kristan-sp.si>
Date: Wed, 8 Nov 2023 18:42:43 +0100
Subject: [PATCH] Dissolve fix (#3502)

---
 wled00/FX.cpp | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/wled00/FX.cpp b/wled00/FX.cpp
index 2b7cd726..f1c861f7 100644
--- a/wled00/FX.cpp
+++ b/wled00/FX.cpp
@@ -604,22 +604,36 @@ static const char _data_FX_MODE_TWINKLE[] PROGMEM = "Twinkle@!,!;!,!;!;;m12=0";
  * Dissolve function
  */
 uint16_t dissolve(uint32_t color) {
+  uint16_t dataSize = (SEGLEN+7) >> 3; //1 bit per LED
+  if (!SEGENV.allocateData(dataSize)) return mode_static(); //allocation failed
+
+  if (SEGENV.call == 0) {
+    memset(SEGMENT.data, 0xFF, dataSize); // start by fading pixels up
+    SEGENV.aux0 = 1;
+  }
+
   for (int j = 0; j <= SEGLEN / 15; j++) {
     if (random8() <= SEGMENT.intensity) {
-      for (size_t times = 0; times < 10; times++) //attempt to spawn a new pixel 10 times
-      {
-        uint16_t i = random16(SEGLEN);
+      for (size_t times = 0; times < 10; times++) { //attempt to spawn a new pixel 10 times
+        unsigned i = random16(SEGLEN);
+        unsigned index = i >> 3;
+        unsigned bitNum = i & 0x07;
+        bool fadeUp = bitRead(SEGENV.data[index], bitNum);
         if (SEGENV.aux0) { //dissolve to primary/palette
-          if (SEGMENT.getPixelColor(i) == SEGCOLOR(1) /*|| wa*/) {
+          if (fadeUp) {
             if (color == SEGCOLOR(0)) {
               SEGMENT.setPixelColor(i, SEGMENT.color_from_palette(i, true, PALETTE_SOLID_WRAP, 0));
             } else {
               SEGMENT.setPixelColor(i, color);
             }
+            bitWrite(SEGENV.data[index], bitNum, false);
             break; //only spawn 1 new pixel per frame per 50 LEDs
           }
         } else { //dissolve to secondary
-          if (SEGMENT.getPixelColor(i) != SEGCOLOR(1)) { SEGMENT.setPixelColor(i, SEGCOLOR(1)); break; }
+          if (!fadeUp) {
+            SEGMENT.setPixelColor(i, SEGCOLOR(1)); break;
+            bitWrite(SEGENV.data[index], bitNum, true);
+          }
         }
       }
     }
@@ -628,6 +642,7 @@ uint16_t dissolve(uint32_t color) {
   if (SEGENV.step > (255 - SEGMENT.speed) + 15U) {
     SEGENV.aux0 = !SEGENV.aux0;
     SEGENV.step = 0;
+    memset(SEGMENT.data, (SEGENV.aux0 ? 0xFF : 0), dataSize); // switch fading
   } else {
     SEGENV.step++;
   }