Use shader storage buffer to pass lights to shader

shaders/hlsl/subpasses/composition.frag

@@ -1,11 +1,8 @@
 // Copyright 2020 Google LLC
 
-[[vk::input_attachment_index(0)]][[vk::binding(0)]] SubpassInput samplerposition;
-[[vk::input_attachment_index(1)]][[vk::binding(1)]] SubpassInput samplerNormal;
-[[vk::input_attachment_index(2)]][[vk::binding(2)]] SubpassInput samplerAlbedo;
-
-#define MAX_NUM_LIGHTS 64
-[[vk::constant_id(0)]] const int NUM_LIGHTS = 64;
+[[vk::input_attachment_index(0)]][[vk::binding(0)]] SubpassInput inputPosition;
+[[vk::input_attachment_index(1)]][[vk::binding(1)]] SubpassInput inputNormal;
+[[vk::input_attachment_index(2)]][[vk::binding(2)]] SubpassInput inputAlbedo;
 
 struct Light {
 	float4 position;
@@ -13,56 +10,37 @@ struct Light {
 	float radius;
 };
 
-struct UBO
-{
-	float4 viewPos;
-	Light lights[MAX_NUM_LIGHTS];
-};
-
-cbuffer ubo : register(b3) { UBO ubo; }
-
+RWStructuredBuffer<Light> lights: register(u3);
 
 float4 main([[vk::location(0)]] float2 inUV : TEXCOORD) : SV_TARGET
 {
 	// Read G-Buffer values from previous sub pass
-	float3 fragPos = samplerposition.SubpassLoad().rgb;
-	float3 normal = samplerNormal.SubpassLoad().rgb;
-	float4 albedo = samplerAlbedo.SubpassLoad();
+	float3 fragPos = inputPosition.SubpassLoad().rgb;
+	float3 normal = inputNormal.SubpassLoad().rgb;
+	float4 albedo = inputAlbedo.SubpassLoad();
 
-	#define ambient 0.15
+	#define ambient 0.05
 
 	// Ambient part
 	float3 fragcolor  = albedo.rgb * ambient;
 
-	for(int i = 0; i < NUM_LIGHTS; ++i)
+	uint lightsLength;
+	uint lightsStride;
+	lights.GetDimensions(lightsLength, lightsStride);
+
+	for(int i = 0; i < lightsLength; ++i)
 	{
-		// Vector to light
-		float3 L = ubo.lights[i].position.xyz - fragPos;
-		// Distance from light to fragment position
+		float3 L = lights[i].position.xyz - fragPos;
 		float dist = length(L);
 
-		// Viewer to fragment
-		float3 V = ubo.viewPos.xyz - fragPos;
-		V = normalize(V);
-
-		// Light to fragment
 		L = normalize(L);
 
-		// Attenuation
-		float atten = ubo.lights[i].radius / (pow(dist, 2.0) + 1.0);
-
-		// Diffuse part
+		float atten = lights[i].radius / (pow(dist, 3.0) + 1.0);
 		float3 N = normalize(normal);
 		float NdotL = max(0.0, dot(N, L));
-		float3 diff = ubo.lights[i].color * albedo.rgb * NdotL * atten;
+		float3 diff = lights[i].color * albedo.rgb * NdotL * atten;
 
-		// Specular part
-		// Specular map values are stored in alpha of albedo mrt
-		float3 R = reflect(-L, N);
-		float NdotR = max(0.0, dot(R, V));
-		//float3 spec = ubo.lights[i].color * albedo.a * pow(NdotR, 32.0) * atten;
-
-		fragcolor += diff;// + spec;
+		fragcolor += diff;
 	}
 
 	return float4(fragcolor, 1.0);