Add shaders re-implemented in HLSL

These were written against the shaders at revision eddd724e7.
There have been changes made since then, which will need to be mirrored.

See `data/hlsl/README.md` for the current status of each sample.

data/hlsl/subpasses/transparent.frag

@@ -0,0 +1,33 @@
+// Copyright 2020 Google LLC
+
+[[vk::input_attachment_index(0)]][[vk::binding(1)]] SubpassInput samplerPositionDepth;
+Texture2D textureTexture : register(t2);
+SamplerState samplerTexture : register(s2);
+
+struct VSOutput
+{
+	float4 Pos : SV_POSITION;
+[[vk::location(0)]] float3 Color : COLOR0;
+[[vk::location(1)]] float2 UV : TEXCOORD0;
+};
+
+[[vk::constant_id(0)]] const float NEAR_PLANE = 0.1f;
+[[vk::constant_id(1)]] const float FAR_PLANE = 256.0f;
+
+float linearDepth(float depth)
+{
+	float z = depth * 2.0f - 1.0f;
+	return (2.0f * NEAR_PLANE * FAR_PLANE) / (FAR_PLANE + NEAR_PLANE - z * (FAR_PLANE - NEAR_PLANE));
+}
+
+float4 main (VSOutput input) : SV_TARGET
+{
+	// Sample depth from deferred depth buffer and discard if obscured
+	float depth = samplerPositionDepth.SubpassLoad().a;
+	if ((depth != 0.0) && (linearDepth(input.Pos.z) > depth))
+	{
+		clip(-1);
+	};
+
+	return textureTexture.Sample(samplerTexture, input.UV);
+}