color_add() that preserves color ratio

AA version of setPixelColor(float)
Fix in AA ratio calculation.

wled00/FX.h

@@ -709,12 +709,15 @@ class WS2812FX {
       makeAutoSegments(bool forceReset = false),
       fixInvalidSegments(),
       setPixelColor(uint16_t n, uint8_t r, uint8_t g, uint8_t b, uint8_t w = 0),
+      setPixelColor(float i, uint8_t r, uint8_t g, uint8_t b, uint8_t w = 0, bool aa = false),
       show(void),
 			setTargetFps(uint8_t fps),
       deserializeMap(uint8_t n=0);
 
     inline void setPixelColor(uint16_t n, uint32_t c)               {setPixelColor(n, byte(c>>16), byte(c>>8), byte(c), byte(c>>24));}
-    inline void setPixelColor(uint16_t n, CRGB &c)    {setPixelColor(n, c.red, c.green, c.blue);}
+    inline void setPixelColor(uint16_t n, CRGB c)                   {setPixelColor(n, c.red, c.green, c.blue);}
+    inline void setPixelColor(float i, uint32_t c, bool aa = false) {setPixelColor(i, byte(c>>16), byte(c>>8), byte(c), byte(c>>24), aa);}
+    inline void setPixelColor(float i, CRGB c, bool aa = false)     {setPixelColor(i, c.red, c.green, c.blue, 0, aa);}
 
     bool
       gammaCorrectBri = false,
@@ -768,6 +771,7 @@ class WS2812FX {
       color_wheel(uint8_t),
       color_from_palette(uint16_t, bool mapping, bool wrap, uint8_t mcol, uint8_t pbri = 255),
       color_blend(uint32_t,uint32_t,uint16_t,bool b16=false),
+      color_add(uint32_t,uint32_t),
       currentColor(uint32_t colorNew, uint8_t tNr),
       gamma32(uint32_t),
       getLastShow(void),

wled00/FX_2Dfcn.cpp

@@ -193,10 +193,16 @@ void /*IRAM_ATTR*/ WS2812FX::setPixelColorXY(float x, float y, byte r, byte g, b
   const uint16_t rows = SEGMENT.virtualHeight();
 
   if (aa) {
-    uint16_t xL = floorf(x * (cols-1));
+    float fX = x * (cols-1);
-    uint16_t xR = ceilf(x * (cols-1));
+    float fL = floorf(x * (cols-1));
-    uint16_t yT = floorf(y * (rows-1));
+    float fR = ceilf(x * (cols-1));
-    uint16_t yB = ceilf(y * (rows-1));
+    float fY = y * (rows-1);
+    float fT = floorf(y * (rows-1));
+    float fB = ceilf(y * (rows-1));
+    uint16_t xL = fL;
+    uint16_t xR = fR;
+    uint16_t yT = fT;
+    uint16_t yB = fB;
     uint32_t cXLYT = getPixelColorXY(xL, yT);
     uint32_t cXRYT = getPixelColorXY(xR, yT);
     uint32_t cXLYB = getPixelColorXY(xL, yB);
@@ -204,30 +210,30 @@ void /*IRAM_ATTR*/ WS2812FX::setPixelColorXY(float x, float y, byte r, byte g, b
 
     if (xL!=xR && yT!=yB) {
       // blend TL pixel
-      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, sqrtf((x - floor(x))*(y - floorf(y)))*UINT16_MAX, true);
+      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, sqrtf((fR - fX)*(fB - fY))*UINT16_MAX, true);
       setPixelColorXY(xR, yT, R(cXLYT), G(cXLYT), B(cXLYT), W(cXLYT));
       // blend TR pixel
-      cXRYT = color_blend(RGBW32(r,g,b,w), cXRYT, sqrtf((ceilf(x) - x)*(y - floorf(y)))*UINT16_MAX, true);
+      cXRYT = color_blend(RGBW32(r,g,b,w), cXRYT, sqrtf((fX - fL)*(fB - fY))*UINT16_MAX, true);
       setPixelColorXY(xR, yT, R(cXRYT), G(cXRYT), B(cXRYT), W(cXRYT));
       // blend BL pixel
-      cXLYB = color_blend(RGBW32(r,g,b,w), cXLYB, sqrtf((x - floor(x))*(ceil(y) - y))*UINT16_MAX, true);
+      cXLYB = color_blend(RGBW32(r,g,b,w), cXLYB, sqrtf((fR - fX)*(fY - fT))*UINT16_MAX, true);
       setPixelColorXY(xL, yB, R(cXLYB), G(cXLYB), B(cXLYB), W(cXLYB));
       // blend BR pixel
-      cXRYB = color_blend(RGBW32(r,g,b,w), cXRYB, sqrtf((ceilf(x) - x)*(ceil(y) - y))*UINT16_MAX, true);
+      cXRYB = color_blend(RGBW32(r,g,b,w), cXRYB, sqrtf((fX - fL)*(fY - fT))*UINT16_MAX, true);
       setPixelColorXY(xR, yB, R(cXRYB), G(cXRYB), B(cXRYB), W(cXRYB));
     } else if (xR!=xL && yT==yB) {
       // blend L pixel
-      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, (x - floor(x))*UINT16_MAX, true);
+      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, (fR - fX)*UINT16_MAX, true);
       setPixelColorXY(xR, yT, R(cXLYT), G(cXLYT), B(cXLYT), W(cXLYT));
       // blend R pixel
-      cXRYT = color_blend(RGBW32(r,g,b,w), cXRYT, (ceilf(x) - x)*UINT16_MAX, true);
+      cXRYT = color_blend(RGBW32(r,g,b,w), cXRYT, (fX - fL)*UINT16_MAX, true);
       setPixelColorXY(xR, yT, R(cXRYT), G(cXRYT), B(cXRYT), W(cXRYT));
     } else if (xR==xL && yT!=yB) {
       // blend T pixel
-      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, (y - floorf(y))*UINT16_MAX, true);
+      cXLYT = color_blend(RGBW32(r,g,b,w), cXLYT, (fB - fY)*UINT16_MAX, true);
       setPixelColorXY(xR, yT, R(cXLYT), G(cXLYT), B(cXLYT), W(cXLYT));
       // blend B pixel
-      cXLYB = color_blend(RGBW32(r,g,b,w), cXLYB, (ceil(y) - y)*UINT16_MAX, true);
+      cXLYB = color_blend(RGBW32(r,g,b,w), cXLYB, (fY - fT)*UINT16_MAX, true);
       setPixelColorXY(xL, yB, R(cXLYB), G(cXLYB), B(cXLYB), W(cXLYB));
     } else {
       // exact match (x & y land on a pixel)

wled00/FX_fcn.cpp

@@ -182,6 +182,35 @@ void WS2812FX::service() {
   _triggered = false;
 }
 
+// anti-aliased normalized version of setPixelColor()
+void /*IRAM_ATTR*/ WS2812FX::setPixelColor(float i, byte r, byte g, byte b, byte w, bool aa)
+{
+  if (i<0.0f || i>1.0f) return; // not normalized
+
+  if (aa) {
+    float fC = i * (SEGLEN-1);
+    float fL = floorf(i * (SEGLEN-1));
+    float fR = ceilf(i * (SEGLEN-1));
+    uint16_t iL = fL;
+    uint16_t iR = fR;
+    uint32_t cIL = getPixelColor(iL);
+    uint32_t cIR = getPixelColor(iR);
+    if (iR!=iL) {
+      // blend L pixel
+      cIL = color_blend(RGBW32(r,g,b,w), cIL, (fR - fC)*UINT16_MAX, true);
+      setPixelColor(iL, R(cIL), G(cIL), B(cIL), W(cIL));
+      // blend R pixel
+      cIR = color_blend(RGBW32(r,g,b,w), cIR, (fC - fL)*UINT16_MAX, true);
+      setPixelColor(iR, R(cIR), G(cIR), B(cIR), W(cIR));
+    } else {
+      // exact match (x & y land on a pixel)
+      setPixelColor(iL, r, g, b, w);
+    }
+  } else {
+    setPixelColor((uint16_t)roundf(i * (SEGLEN-1)), r, g, b, w);
+  }
+}
+
 void IRAM_ATTR WS2812FX::setPixelColor(uint16_t i, byte r, byte g, byte b, byte w)
 {
   uint8_t segIdx = SEGLEN ? _segment_index : _mainSegment;
@@ -887,6 +916,24 @@ uint32_t IRAM_ATTR WS2812FX::color_blend(uint32_t color1, uint32_t color2, uint1
   return RGBW32(r3, g3, b3, w3);
 }
 
+/*
+ * color add function that preserves ratio
+ * idea: https://github.com/Aircoookie/WLED/pull/2465 by https://github.com/Proto-molecule
+ */
+uint32_t WS2812FX::color_add(uint32_t c1, uint32_t c2)
+{
+  uint32_t r = R(c1) + R(c2);
+  uint32_t g = G(c1) + G(c2);
+  uint32_t b = B(c1) + B(c2);
+  uint32_t w = W(c1) + W(c2);
+  uint16_t max = r;
+  if (g > max) max = g;
+  if (b > max) max = b;
+  if (w > max) max = w;
+  if (max < 256) return RGBW32(r, g, b, w);
+  else           return RGBW32(r * 255 / max, g * 255 / max, b * 255 / max, w * 255 / max);
+}
+
 /*
  * Fills segment with color
  */