From 8a03b274ec48058439a4b97ffeca44f0f524c2d7 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Mon, 2 Feb 2026 23:30:41 +0100
Subject: [PATCH 1/2] spots effect improvements

* avoid gaps on left/light side of strip, by using higher accuracy zoneLength
* prevent overflows
* ensure that zones calculation are performed in full 32bit
* fix wrong slider name in "spots fade"
---
 wled00/FX.cpp | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/wled00/FX.cpp b/wled00/FX.cpp
index d60c525261..b8bfe24d51 100644
--- a/wled00/FX.cpp
+++ b/wled00/FX.cpp
@@ -2952,20 +2952,21 @@ static uint16_t spots_base(uint16_t threshold)
   if (SEGLEN <= 1) return mode_static();
   if (!SEGMENT.check2) SEGMENT.fill(SEGCOLOR(1));
 
-  unsigned maxZones = SEGLEN >> 2;
-  unsigned zones = 1 + ((SEGMENT.intensity * maxZones) >> 8);
+  unsigned maxZones = max(1U, SEGLEN >> 2); // prevents "0 zones"
+  unsigned zones = 1U + ((uint32_t(SEGMENT.intensity) * maxZones) >> 8);
   unsigned zoneLen = SEGLEN / zones;
-  unsigned offset = (SEGLEN - zones * zoneLen) >> 1;
+  unsigned zoneLen8 = zones < 8 ? zoneLen * 8 : SEGLEN / (zones >> 3); // zoneLength * 8 -> avoids gaps at right/left sides
+  unsigned offset = (uint32_t(SEGLEN) - ((zones * zoneLen8)>>3)) >> 1;
 
   for (unsigned z = 0; z < zones; z++)
   {
-    unsigned pos = offset + z * zoneLen;
+    unsigned pos = offset +((z * zoneLen8)>>3);
     for (unsigned i = 0; i < zoneLen; i++)
     {
       unsigned wave = triwave16((i * 0xFFFF) / zoneLen);
       if (wave > threshold) {
-        unsigned index = 0 + pos + i;
-        unsigned s = (wave - threshold)*255 / (0xFFFF - threshold);
+        unsigned index = pos + i;
+        unsigned s = ((wave - threshold)*255 / (0xFFFF - threshold)) & 0xFF; // & 0xFF prevents overflow in next line
         SEGMENT.setPixelColor(index, color_blend(SEGMENT.color_from_palette(index, true, PALETTE_SOLID_WRAP, 0), SEGCOLOR(1), uint8_t(255-s)));
       }
     }
@@ -2991,7 +2992,7 @@ uint16_t mode_spots_fade()
   unsigned tr = (t >> 1) + (t >> 2);
   return spots_base(tr);
 }
-static const char _data_FX_MODE_SPOTS_FADE[] PROGMEM = "Spots Fade@Spread,Width,,,,,Overlay;!,!;!";
+static const char _data_FX_MODE_SPOTS_FADE[] PROGMEM = "Spots Fade@Speed,Width,,,,,Overlay;!,!;!";
 
 //each needs 12 bytes
 typedef struct Ball {

From e2bee4fdb27a753f79ede1d7e633d8a7dbff5da8 Mon Sep 17 00:00:00 2001
From: Frank <91616163+softhack007@users.noreply.github.com>
Date: Mon, 2 Feb 2026 23:56:30 +0100
Subject: [PATCH 2/2] fixpoint scaling bugfix

* use named constants for fixed point scaling
* remove buggy "SEGLEN / (zones >>3)" shortcut
* remove an unnecessary casts to uint32_t
---
 wled00/FX.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/wled00/FX.cpp b/wled00/FX.cpp
index b8bfe24d51..47e5a2c700 100644
--- a/wled00/FX.cpp
+++ b/wled00/FX.cpp
@@ -2952,15 +2952,19 @@ static uint16_t spots_base(uint16_t threshold)
   if (SEGLEN <= 1) return mode_static();
   if (!SEGMENT.check2) SEGMENT.fill(SEGCOLOR(1));
 
+  // constants for fixed point scaling
+  constexpr uint8_t  ZONELEN_FP_SHIFT = 3;
+  constexpr uint32_t ZONELEN_FP_SCALE = 1U << ZONELEN_FP_SHIFT;
+
   unsigned maxZones = max(1U, SEGLEN >> 2); // prevents "0 zones"
   unsigned zones = 1U + ((uint32_t(SEGMENT.intensity) * maxZones) >> 8);
-  unsigned zoneLen = SEGLEN / zones;
-  unsigned zoneLen8 = zones < 8 ? zoneLen * 8 : SEGLEN / (zones >> 3); // zoneLength * 8 -> avoids gaps at right/left sides
-  unsigned offset = (uint32_t(SEGLEN) - ((zones * zoneLen8)>>3)) >> 1;
+  unsigned zoneLen  = SEGLEN / zones;
+  unsigned zoneLen8 = (SEGLEN * ZONELEN_FP_SCALE) / zones; // zoneLength * 8 (fixed‑point) -> avoids gaps at right/left sides
+  unsigned offset   = (SEGLEN - ((zones * zoneLen8) >> ZONELEN_FP_SHIFT)) >> 1;
 
   for (unsigned z = 0; z < zones; z++)
   {
-    unsigned pos = offset +((z * zoneLen8)>>3);
+    unsigned pos = offset + ((z * zoneLen8) >> ZONELEN_FP_SHIFT);
     for (unsigned i = 0; i < zoneLen; i++)
     {
       unsigned wave = triwave16((i * 0xFFFF) / zoneLen);