From 25382cb6f21b6136b0f490a618ce8d494ca5cd38 Mon Sep 17 00:00:00 2001
From: Fred Sundvik <fsundvik@gmail.com>
Date: Wed, 11 May 2016 22:06:26 +0300
Subject: [PATCH] Fix compute_gradient_color

---
 led_test.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/led_test.c b/led_test.c
index ed65a0baa..d358ef81e 100644
--- a/led_test.c
+++ b/led_test.c
@@ -86,10 +86,13 @@ static uint8_t crossfade_start_frame[NUM_ROWS][NUM_COLS];
 static uint8_t crossfade_end_frame[NUM_ROWS][NUM_COLS];
 
 static uint8_t compute_gradient_color(float t, float index, float num) {
-    float d = fabs(index - t);
-    if (d > num / 2.0f) {
+    const float target = t * (num - 1.0f);
+    const float half_num = num / 2.0f;
+    float d = fabs(index - target);
+    if (d > half_num) {
         d = num - d;
     }
+    d = 1.0f - (d / half_num);
     return (uint8_t)(255.0f * d);
 }