From 9850d68939b86262eae9f0da01ff1c11daafcdc3 Mon Sep 17 00:00:00 2001
From: hunterk <hunter_kaller@yahoo.com>
Date: Mon, 24 Feb 2020 16:35:12 -0600
Subject: [PATCH] add grid-blend-hybrid shader and preset

---
 interpolation/grid-blend-hybrid.slangp        |  4 ++
 interpolation/shaders/grid-blend-hybrid.slang | 58 +++++++++++++++++++
 2 files changed, 62 insertions(+)
 create mode 100644 interpolation/grid-blend-hybrid.slangp
 create mode 100644 interpolation/shaders/grid-blend-hybrid.slang

diff --git a/interpolation/grid-blend-hybrid.slangp b/interpolation/grid-blend-hybrid.slangp
new file mode 100644
index 0000000..63e7cdd
--- /dev/null
+++ b/interpolation/grid-blend-hybrid.slangp
@@ -0,0 +1,4 @@
+shaders = 1
+
+shader0 = shaders/grid-blend-hybrid.slang
+filter_linear0 = true
\ No newline at end of file
diff --git a/interpolation/shaders/grid-blend-hybrid.slang b/interpolation/shaders/grid-blend-hybrid.slang
new file mode 100644
index 0000000..09f24cc
--- /dev/null
+++ b/interpolation/shaders/grid-blend-hybrid.slang
@@ -0,0 +1,58 @@
+#version 450
+
+// based on Cole Cecil's
+// Scaling Pixel ARt Without Destroying It
+// https://colececil.io/blog/2017/scaling-pixel-art-without-destroying-it/
+
+// This shader needs bilinear filtering
+
+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 vec2 textureCoords;
+
+void main()
+{
+   gl_Position = global.MVP * Position;
+   vTexCoord = TexCoord * 1.00001;
+   textureCoords = vTexCoord * params.SourceSize.xy;
+}
+
+#pragma stage fragment
+layout(location = 0) in vec2 vTexCoord;
+layout(location = 1) in vec2 textureCoords;
+layout(location = 0) out vec4 FragColor;
+layout(set = 0, binding = 2) uniform sampler2D Source;
+
+void main()
+{
+   // For the current screen pixel, find its location in relation to the nearest texels).
+   vec2 locationWithinTexel = fract(textureCoords);
+   
+   // How many texels are in each pixel
+   vec2 texelsPerPixel = params.OutputSize.zw * params.SourceSize.xy;
+   
+   // Determine how much (if at all) we need to interpolate between the colors of the nearest texels
+   // No interpolation means it’s using nearest neighbor filtering.
+   // Interpolation means it’s using bilinear filtering
+   vec2 interpolationAmount = clamp(locationWithinTexel / texelsPerPixel, 0., 0.5)
+         + clamp((locationWithinTexel - 1.) / texelsPerPixel + 0.5, 0., 0.5);
+         
+   // Given the interpolation amount, calculate and return the color of the pixel.
+   vec2 finalTextureCoords = (floor(textureCoords) + interpolationAmount) * params.SourceSize.zw;
+   FragColor = vec4(texture(Source, finalTextureCoords).rgb, 1.0);
+}
\ No newline at end of file