From 28f08dcfea068bc7786686c98dba7dba3188bb42 Mon Sep 17 00:00:00 2001
From: hunterk <hunter_kaller@yahoo.com>
Date: Sun, 16 Feb 2020 09:41:42 -0600
Subject: [PATCH] add anti-flicker shader

---
 misc/anti-flicker.glsl | 130 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 misc/anti-flicker.glsl

diff --git a/misc/anti-flicker.glsl b/misc/anti-flicker.glsl
new file mode 100644
index 0000000..3b897f8
--- /dev/null
+++ b/misc/anti-flicker.glsl
@@ -0,0 +1,130 @@
+/*
+	Anti-Flicker shader
+	by hunterk
+	License: public domain
+	
+	This shader detects large variations in luminance from frame to frame
+	and then blends frames to smooth the transition. In flicker-based
+	shadow effects, this should result in true transparency.
+*/
+
+#pragma parameter lum_diff_thresh "Flicker Luma Diff. Threshold" 0.5 0.0 1.0 0.05
+
+#if defined(VERTEX)
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING out
+#define COMPAT_ATTRIBUTE in
+#define COMPAT_TEXTURE texture
+#else
+#define COMPAT_VARYING varying 
+#define COMPAT_ATTRIBUTE attribute 
+#define COMPAT_TEXTURE texture2D
+#endif
+
+#ifdef GL_ES
+#define COMPAT_PRECISION mediump
+#else
+#define COMPAT_PRECISION
+#endif
+
+COMPAT_ATTRIBUTE vec4 VertexCoord;
+COMPAT_ATTRIBUTE vec4 TexCoord;
+COMPAT_VARYING vec4 TEX0;
+
+uniform mat4 MVPMatrix;
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+
+// compatibility #defines
+#define vTexCoord TEX0.xy
+#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
+#define OutSize vec4(OutputSize, 1.0 / OutputSize)
+
+void main()
+{
+   gl_Position = MVPMatrix * VertexCoord;
+   TEX0.xy = TexCoord.xy;
+}
+
+#elif defined(FRAGMENT)
+
+#ifdef GL_ES
+#ifdef GL_FRAGMENT_PRECISION_HIGH
+precision highp float;
+#else
+precision mediump float;
+#endif
+#define COMPAT_PRECISION mediump
+#else
+#define COMPAT_PRECISION
+#endif
+
+#if __VERSION__ >= 130
+#define COMPAT_VARYING in
+#define COMPAT_TEXTURE texture
+out COMPAT_PRECISION vec4 FragColor;
+#else
+#define COMPAT_VARYING varying
+#define FragColor gl_FragColor
+#define COMPAT_TEXTURE texture2D
+#endif
+
+uniform COMPAT_PRECISION int FrameDirection;
+uniform COMPAT_PRECISION int FrameCount;
+uniform COMPAT_PRECISION vec2 OutputSize;
+uniform COMPAT_PRECISION vec2 TextureSize;
+uniform COMPAT_PRECISION vec2 InputSize;
+uniform sampler2D Texture;
+uniform sampler2D PrevTexture;
+uniform sampler2D Prev1Texture;
+COMPAT_VARYING vec4 TEX0;
+
+// compatibility #defines
+#define Source Texture
+#define vTexCoord TEX0.xy
+
+#define SourceSize vec4(TextureSize, 1.0 / TextureSize) //either TextureSize or InputSize
+#define OutSize vec4(OutputSize, 1.0 / OutputSize)
+
+#ifdef PARAMETER_UNIFORM
+uniform COMPAT_PRECISION float lum_diff_thresh;
+#else
+#define lum_diff_thresh 0.5
+#endif
+
+vec3 RGBtoYIQ(vec3 RGB)
+  {
+     const mat3 m = mat3(
+     0.2989, 0.5870, 0.1140,
+     0.5959, -0.2744, -0.3216,
+     0.2115, -0.5229, 0.3114);
+     return RGB * m;
+  }
+
+vec3 YIQtoRGB(vec3 YIQ)
+  {
+     const mat3 m = mat3(
+     1.0, 0.956, 0.6210,
+     1.0, -0.2720, -0.6474,
+     1.0, -1.1060, 1.7046);
+   return YIQ * m;
+  }
+
+void main()
+{
+    vec3 curr = RGBtoYIQ(COMPAT_TEXTURE(Source, vTexCoord).rgb);
+    vec3 prev0 = RGBtoYIQ(COMPAT_TEXTURE(PrevTexture, vTexCoord).rgb);
+    vec3 prev1 = RGBtoYIQ(COMPAT_TEXTURE(Prev1Texture, vTexCoord).rgb);
+
+    if((abs(curr.r - prev0.r) > lum_diff_thresh) && (abs(curr.r - prev1.r) < 1.0 - lum_diff_thresh))
+      FragColor.rgb = (prev0 + curr) / 2.;
+    else
+      FragColor.rgb = curr;
+    FragColor.rgb = YIQtoRGB(FragColor.rgb);
+    FragColor.a = 1.0;
+} 
+#endif