From 8d2bf6a8fe5eb3419525e83ecb3c98f5749d79c8 Mon Sep 17 00:00:00 2001
From: hunterk <hunter_kaller@yahoo.com>
Date: Fri, 16 Feb 2018 16:38:09 -0600
Subject: [PATCH] add snes-blend-and-bob shader

---
 misc/snes-blend-and-bob.slang | 81 +++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 misc/snes-blend-and-bob.slang

diff --git a/misc/snes-blend-and-bob.slang b/misc/snes-blend-and-bob.slang
new file mode 100644
index 0000000..540271f
--- /dev/null
+++ b/misc/snes-blend-and-bob.slang
@@ -0,0 +1,81 @@
+#version 450
+
+/*
+   Bob-Deinterlacing
+   Author: hunterk
+   License: Public domain
+   
+   Note: This shader is designed to work with the typical interlaced output from an emulator, which displays both even and odd fields twice.
+   As such, it is inappropriate for general video use unless the video has already been similarly woven beforehand.
+*/
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+} params;
+
+layout(std140, set = 0, binding = 0) uniform UBO
+{
+	mat4 MVP;
+} global;
+
+#pragma stage vertex
+layout(location = 0) in vec4 Position;
+layout(location = 1) in vec2 TexCoord;
+layout(location = 0) out vec2 vTexCoord;
+layout(location = 1) out vec4 t1;
+
+void main()
+{
+	gl_Position = global.MVP * Position;
+	vTexCoord = TexCoord;
+	vec2 ps = params.SourceSize.zw;
+	float dx = ps.x;
+	float dy = ps.y;
+	t1 = vTexCoord.xxxy + vec4( -dx, 0., dx, 0.); // L, C, R
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 1) in vec4 t1;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+void main()
+{
+	float y = 0.0;
+	vec4 c;
+	vec4 l;
+	vec4 r;
+	// assume anything with a vertical resolution greater than 400 lines is interlaced
+	if (params.SourceSize.y > 400.0) y = params.SourceSize.y * vTexCoord.y + float(params.FrameCount);
+	else	y = 2.000001 * params.SourceSize.y * vTexCoord.y;
+
+	if (mod(y, 2.0) > 0.99999)
+	{
+		c = vec4(texture(Source, t1.yw + vec2(0.0, params.SourceSize.w)));
+		l = vec4(texture(Source, t1.xw + vec2(0.0, params.SourceSize.w)));
+		r = vec4(texture(Source, t1.zw + vec2(0.0, params.SourceSize.w)));
+	}
+	else
+	{
+		c = texture(Source, t1.yw);
+		l = texture(Source, t1.xw);
+		r = texture(Source, t1.zw);
+	}
+	
+	vec4 final;
+	if (params.SourceSize.x < 500.0) final = c;
+	else
+	{
+		// pixel location
+		float fp = round(fract(0.5*vTexCoord.x*params.SourceSize.x));
+
+		// output
+		final = (((l.x == c.x)||(r.x == c.x))&&((l.y == c.y)||(r.y == c.y))&&((l.z == c.z)||(r.z == c.z))) ? c : (fp > 0.5 ? mix(c,r,0.5) : mix(c,l,0.5));
+	}
+	FragColor = final;
+}
\ No newline at end of file