From 6d58c143c00d98ff142959047b1a64fcc22c51a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fernando=20Garc=C3=ADa=20Li=C3=B1=C3=A1n?=
 <fernando.garli@gmail.com>
Date: Sun, 21 Apr 2019 18:53:19 +0200
Subject: [PATCH] Added dithering as an ALS post-processing effect to prevent
 banding

---
 Shaders/filters-ALS.frag | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Shaders/filters-ALS.frag b/Shaders/filters-ALS.frag
index 92302f5ae..cb69c2a31 100644
--- a/Shaders/filters-ALS.frag
+++ b/Shaders/filters-ALS.frag
@@ -20,6 +20,7 @@ uniform bool use_IR_vision;
 uniform int display_xsize;
 uniform int display_ysize;
 
+float rand2D(in vec2 co);
 float Noise2D(in vec2 coord, in float wavelength);
 
 vec3 gamma_correction (in vec3 color) {
@@ -108,6 +109,11 @@ return color;
 
 vec3 filter_combined (in vec3 color) {
 
+    // Apply some dithering to eliminate banding caused by rendering to a
+    // 32 bpp framebuffer
+    float dither_noise = rand2D(gl_FragCoord.xy);
+    color += mix(-0.5/255.0, 0.5/255.0, dither_noise);
+
 if (use_filtering == false)
 	{
 	return color;