Added fill_gradient

3 files changed, 92 insertions, 0 deletions

diff --git a/colorutils.cpp b/colorutils.cpp
index e0a82882..12e9b0ad 100644
--- a/colorutils.cpp
+++ b/colorutils.cpp
@@ -27,6 +27,74 @@ void fill_rainbow( struct CRGB * pFirstLED, int numToFill,
 }
 
 
+#define saccum87 int16_t
+
+void fill_gradient( CRGB* leds,
+                    uint16_t startpos, CHSV startcolor,
+                    uint16_t endpos,   CHSV endcolor,
+                    TGradientDirectionCode directionCode )
+{
+    // if the points are in the wrong order, straighten them
+    if( endpos < startpos ) {
+        uint16_t t = endpos;
+        CHSV tc = endcolor;
+        startpos = t;
+        startcolor = tc;
+        endcolor = startcolor;
+        endpos = startpos;
+    }
+    
+    saccum87 huedistance87;
+    saccum87 satdistance87;
+    saccum87 valdistance87;
+    
+    satdistance87 = (endcolor.sat - startcolor.sat) << 7;
+    valdistance87 = (endcolor.val - startcolor.val) << 7;
+    
+    uint8_t huedelta8 = endcolor.hue - startcolor.hue;
+    
+    if( directionCode == SHORTEST_HUES ) {
+        directionCode = FORWARD_HUES;
+        if( huedelta8 > 127) {
+            directionCode = BACKWARD_HUES;
+        }
+    }
+    
+    if( directionCode == LONGEST_HUES ) {
+        directionCode = FORWARD_HUES;
+        if( huedelta8 < 128) {
+            directionCode = BACKWARD_HUES;
+        }
+    }
+    
+    if( directionCode == FORWARD_HUES) {
+        huedistance87 = huedelta8 << 7;
+    }
+    else /* directionCode == BACKWARD_HUES */
+    {
+        huedistance87 = (uint8_t)(256 - huedelta8) << 7;
+        huedistance87 = -huedistance87;
+    }
+    
+    uint16_t pixeldistance = endpos - startpos;
+    uint16_t p2 = pixeldistance / 2;
+    int16_t divisor = p2 ? p2 : 1;
+    saccum87 huedelta87 = huedistance87 / divisor;
+    saccum87 satdelta87 = satdistance87 / divisor;
+    saccum87 valdelta87 = valdistance87 / divisor;
+    
+    accum88 hue88 = startcolor.hue << 8;
+    accum88 sat88 = startcolor.sat << 8;
+    accum88 val88 = startcolor.val << 8;
+    for( uint16_t i = startpos; i <= endpos; i++) {
+        leds[i] = CHSV( hue88 >> 8, sat88 >> 8, val88 >> 8);
+        hue88 += huedelta87;
+        sat88 += satdelta87;
+        val88 += valdelta87;
+    }
+}
+
+
 
 void nscale8_video( CRGB* leds, uint16_t num_leds, uint8_t scale)
 {
diff --git a/colorutils.h b/colorutils.h
index 457aec57..44b2855b 100644
--- a/colorutils.h
+++ b/colorutils.h
@@ -15,6 +15,29 @@ void fill_rainbow( struct CRGB * pFirstLED, int numToFill,
                    uint8_t deltahue = 5);
 
 
+// fill_gradient - fill a range of LEDs with a smooth gradient
+//                 between two specified HSV colors.
+//                 Since 'hue' is a value around a color wheel,
+//                 there are always two ways to sweep from one hue
+//                 to another.
+//                 This function lets you specify which way you want
+//                 the hue gradient to sweep around the color wheel:
+//                   FORWARD_HUES: hue always goes clockwise
+//                   BACKWARD_HUES: hue always goes counter-clockwise
+//                   SHORTEST_HUES: hue goes whichever way is shortest
+//                   LONGEST_HUES: hue goes whichever way is longest
+//                 The default is SHORTEST_HUES, as this is nearly
+//                 always what is wanted.
+//
+typedef enum { FORWARD_HUES, BACKWARD_HUES, SHORTEST_HUES, LONGEST_HUES } TGradientDirectionCode;
+
+void fill_gradient( struct CRGB* leds,
+                    uint16_t startpos, CHSV startcolor,
+                    uint16_t endpos,   CHSV endcolor,
+                    TGradientDirectionCode directionCode = SHORTEST_HUES );
+
+
+
 // fadeLightBy and fade_video - reduce the brightness of an array
 //                              of pixels all at once.  Guaranteed
 //                              to never fade all the way to black.
diff --git a/preview_changes.txt b/preview_changes.txt
index caa45100..bc69c59f 100644
--- a/preview_changes.txt
+++ b/preview_changes.txt
@@ -16,3 +16,4 @@
 * Added map8
 * Adjusted VIRTAL_BITS of dithering from a flickery 8 to a more solid 3
 * Added array versions of fade_video, fade_raw, and some variations
+* Added fill_gradient