add snes-hires-blend shader

crt/shaders/snes-hires-blend.slang

@@ -0,0 +1,50 @@
+#version 450
+
+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()
+{
+	// pixel location
+	float fp = round(fract(0.5*vTexCoord.x*params.SourceSize.x));
+
+	// reading the texels
+	vec3 l = texture(Source, t1.xw).xyz;
+	vec3 c = texture(Source, t1.yw).xyz;
+	vec3 r = texture(Source, t1.zw).xyz;
+
+	// output
+	FragColor = vec4((params.SourceSize.x > 500) ? (fp == 0 ? mix(c,r,0.5) : mix(c,l,0.5)) : c, 1.0);
+}