Added transparent forward pass as third subpass, demonstrate preserve attachment

data/shaders/subpasses/transparent.frag

@@ -0,0 +1,33 @@
+#version 450
+
+#extension GL_ARB_separate_shader_objects : enable
+#extension GL_ARB_shading_language_420pack : enable
+
+layout (input_attachment_index = 1, binding = 1) uniform subpassInput samplerPositionDepth;
+
+layout (location = 0) in vec3 inColor;
+layout (location = 1) in vec2 inUV;
+
+layout (location = 0) out vec4 outColor;
+
+layout (constant_id = 0) const float NEAR_PLANE = 0.1f;
+layout (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));	
+}
+
+void main () 
+{
+	// Sample depth from deferred depth buffer and discard if obscured
+	float depth = subpassLoad(samplerPositionDepth).a;
+	if (linearDepth(gl_FragCoord.z) > depth)
+	{
+		discard;
+	};
+
+	outColor.rgb = vec3(0.0, 0.25, 0.86);
+	outColor.a = 0.5;
+}