From 65cb75e53c57bb492f9af1fa573e876e4dd1fab9 Mon Sep 17 00:00:00 2001
From: MajorPainTheCactus <thedailytalenewspaper@gmail.com>
Date: Sat, 4 Sep 2021 11:17:02 +0100
Subject: [PATCH] Added integer scaling mode pixel perfect scanline shader for
 use with the new HDR mode in RetroArch

---
 .../shaders/integer-scaling-scanlines.slang   | 89 +++++++++++++++++++
 .../shaders/integer-scaling-scanlines.slangp  |  4 +
 2 files changed, 93 insertions(+)
 create mode 100644 scanlines/shaders/integer-scaling-scanlines.slang
 create mode 100644 scanlines/shaders/integer-scaling-scanlines.slangp

diff --git a/scanlines/shaders/integer-scaling-scanlines.slang b/scanlines/shaders/integer-scaling-scanlines.slang
new file mode 100644
index 0000000..7fc50f4
--- /dev/null
+++ b/scanlines/shaders/integer-scaling-scanlines.slang
@@ -0,0 +1,89 @@
+/* 
+Simple pixel perfect scanlines for use *only* with interger scaling mode. 
+Perfect for low res output and low performance machines.
+Also great if you dont want any moire patterns pin sharp scanlines 
+Use in combination with HDR mode in latest RetroArch and very bright 
+HDR monitors to get 'glowing' scanlines much like the original CRT's but sharper 
+
+Recommended setting for 720p 1 pixel width scalines at 2x or 3x scalings
+Recommended setting for 1080p 2 or 3 pixel width scalines at 4x or 5x scalings
+Recommended setting for 4K 4 or 5 pixel width scalines at 8x or 9x scalings
+*/
+
+#version 450
+
+layout(push_constant) uniform Push
+{
+	vec4 SourceSize;
+	vec4 OriginalSize;
+	vec4 OutputSize;
+	uint FrameCount;
+   float ScanlineWidth;
+   float ScreenWidth;
+   float ScreenHeight; 
+} params;
+
+#pragma parameter ScanlineWidth "Scanline Width"  4.0    0.0 20.0   1.0
+#pragma parameter ScreenWidth   "Screen Width"    3840.0 0.0 7680.0 1.0
+#pragma parameter ScreenHeight  "Screen Height"   2160.0 0.0 4320.0 1.0
+
+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 float Scale;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord;
+
+   vec2 ScreenSize = max(params.OutputSize.xy, vec2(params.ScreenWidth, params.ScreenHeight));
+
+   if((params.SourceSize.x > ScreenSize.x) || (params.SourceSize.y > ScreenSize.y))
+   {
+	   Scale = 1.0;
+   }
+   else 
+   {
+      float ScaleFactor = 2.0;
+        
+      while(((params.SourceSize.x * ScaleFactor) <= ScreenSize.x) && ((params.SourceSize.y * ScaleFactor) <= ScreenSize.y))
+    	{
+	      ScaleFactor += 1.0;
+      }
+
+	   Scale = ScaleFactor - 1.0;
+   }
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 1) in float Scale;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+float ModInteger(float a, float b) 
+{
+    float m = a - floor((a + 0.5) / b) * b;
+    return floor(m + 0.5);
+}
+
+void main()
+{
+   vec2 InPixels = (vTexCoord * params.SourceSize.xy) * vec2(Scale);
+
+   if(ModInteger(floor(InPixels.y), Scale) < params.ScanlineWidth)
+   {
+      FragColor = vec4(texture(Source, vTexCoord).xyz, 1.0);
+   }
+   else
+   {
+      FragColor = vec4(0.0,0.0,0.0,1.0);
+   }
+}
diff --git a/scanlines/shaders/integer-scaling-scanlines.slangp b/scanlines/shaders/integer-scaling-scanlines.slangp
new file mode 100644
index 0000000..b817f7d
--- /dev/null
+++ b/scanlines/shaders/integer-scaling-scanlines.slangp
@@ -0,0 +1,4 @@
+shaders = 1
+
+shader0 = integer-scaling-scanlines.slang
+filter_linear0 = false