Support lighting using a graphics buffer that is kep open!

Assets/source/RootConstants.hlsl

@@ -1,5 +1,13 @@
 #ifndef ROOT_CONSTANTS_HLSL
 #define ROOT_CONSTANTS_HLSL
+ 
+struct PointLight
+{
+    float3 Position;
+    float  Radius;
+    float3 Color;
+    float  Intensity;
+};
 
 cbuffer RootConstants : register(b0, space0)
 {
@@ -16,6 +24,9 @@ cbuffer RootConstants : register(b0, space0)
     float    LightPad;
     float3   LightColor;
     float    AmbientIntensity;
+
+    uint     LightBufferIndex;
+    uint     ActiveLightCount;
 };
 
 

Assets/source/SolidColor.frag.hlsl

@@ -1,10 +1,46 @@
 #include "RootConstants.hlsl"
 
-float4 main(float4 Color : TEXCOORD0, float3 WorldNormal : TEXCOORD1) : SV_Target0
+struct Input
 {
-    float3 N = normalize(WorldNormal);
-    float  NdotL = saturate(dot(N, -LightDirection));
-    float3 diffuse = Color.rgb * LightColor * NdotL;
-    float3 ambient = Color.rgb * AmbientIntensity;
-    return float4(diffuse + ambient, Color.a);
+    float4 Color         : TEXCOORD0;
+    float3 WorldNormal   : TEXCOORD1;
+    float3 WorldPosition : TEXCOORD2;
+};
+
+float4 main(Input input) : SV_Target0
+{
+    float3 normal = normalize(input.WorldNormal);
+
+    // Initial ambient component
+    float3 result = input.Color.rgb * LightColor * AmbientIntensity;
+
+    // Directional light contribution
+    float ndotl = max(dot(normal, -LightDirection), 0.0);
+    result += input.Color.rgb * LightColor * ndotl;
+
+    // Point lights
+    if (ActiveLightCount > 0)
+    {
+        StructuredBuffer<PointLight> pointLights = ResourceDescriptorHeap[LightBufferIndex];
+        
+        for (uint i = 0; i < ActiveLightCount; ++i)
+        {
+            PointLight light = pointLights[i];
+
+            float3 lightDir = light.Position - input.WorldPosition;
+            float  dist     = length(lightDir);
+            
+            if (dist < light.Radius)
+            {
+                lightDir = normalize(lightDir);
+                float attenuation = 1.0 - (dist / light.Radius);
+                attenuation = max(attenuation, 0.0);
+
+                float pndotl = max(dot(normal, lightDir), 0.0);
+                result += light.Color * input.Color.rgb * pndotl * attenuation * light.Intensity;
+            }
+        }
+    }
+
+    return float4(result, input.Color.a);
 }

Assets/source/Triangle.vert.hlsl

@@ -2,6 +2,7 @@ struct Output
 {
     float4 Color : TEXCOORD0;
     float3 WorldNormal : TEXCOORD1;
+    float3 WorldPosition : TEXCOORD2;
     float4 Position : SV_Position;
 };
 
@@ -20,8 +21,10 @@ Output main(uint vertexIndex : SV_VertexID)
     float3 normal = asfloat(buffer.Load3(offset + 12));
     float4 col = asfloat(buffer.Load4(offset + 24));
 
-    output.Position = mul(ViewProjection, mul(Model, float4(pos, 1.0f)));
+    float4 worldPos = mul(Model, float4(pos, 1.0f));
+    output.Position = mul(ViewProjection, worldPos);
     output.Color = col;
+    output.WorldPosition = worldPos.xyz;
     
     float3 worldNormal = mul((float3x3)Model, normal);
     output.WorldNormal = worldNormal;