pack directional shadow maps into a cubemap

Effects/DeferredPBREffect.cs

@@ -9,8 +9,10 @@ namespace Kav
         EffectParameter gAlbedoParam;
         EffectParameter gNormalParam;
         EffectParameter gMetallicRoughnessParam;
+        EffectParameter shadowMapParam;
 
         EffectParameter eyePositionParam;
+
         PointLightCollection pointLightCollection;
         DirectionalLightCollection directionalLightCollection;
 
@@ -18,6 +20,7 @@ namespace Kav
         public Texture2D GAlbedo { get; set; }
         public Texture2D GNormal { get; set; }
         public Texture2D GMetallicRoughness { get; set; }
+        public TextureCube DirectionalShadowMap { get; set; }
 
         public Vector3 EyePosition { get; set; }
 
@@ -49,7 +52,8 @@ namespace Kav
 
             DirectionalLights = new DirectionalLightCollection(
                 Parameters["DirectionalLightDirections"],
-                Parameters["DirectionalLightColors"]
+                Parameters["DirectionalLightColors"],
+                Parameters["DirectionalLightMatrices"]
             );
         }
 
@@ -75,7 +79,8 @@ namespace Kav
 
             DirectionalLights = new DirectionalLightCollection(
                 Parameters["DirectionalLightDirections"],
-                Parameters["DirectionalLightColors"]
+                Parameters["DirectionalLightColors"],
+                Parameters["DirectionalLightMatrices"]
             );
 
             for (int i = 0; i < MaxDirectionalLights; i++)
@@ -95,6 +100,7 @@ namespace Kav
             gAlbedoParam.SetValue(GAlbedo);
             gNormalParam.SetValue(GNormal);
             gMetallicRoughnessParam.SetValue(GMetallicRoughness);
+            shadowMapParam.SetValue(DirectionalShadowMap);
 
             eyePositionParam.SetValue(EyePosition);
         }
@@ -105,6 +111,7 @@ namespace Kav
             gAlbedoParam = Parameters["gAlbedo"];
             gNormalParam = Parameters["gNormal"];
             gMetallicRoughnessParam = Parameters["gMetallicRoughness"];
+            shadowMapParam = Parameters["shadowMap"];
 
             eyePositionParam = Parameters["EyePosition"];
         }

Effects/DirectionalLightCollection.cs

@@ -8,14 +8,20 @@ namespace Kav
         private readonly Vector3[] directions = new Vector3[4];
         private readonly Vector3[] colors = new Vector3[4];
         private readonly float[] intensities = new float[4];
+        private readonly Matrix[] lightSpaceMatrices = new Matrix[4];
 
         readonly EffectParameter lightDirectionsParam;
         readonly EffectParameter lightColorsParam;
+        readonly EffectParameter lightSpaceMatricesParam;
 
-        public DirectionalLightCollection(EffectParameter lightDirectionsParam, EffectParameter lightColorsParam)
-        {
+        public DirectionalLightCollection(
+            EffectParameter lightDirectionsParam,
+            EffectParameter lightColorsParam,
+            EffectParameter lightSpaceMatricesParam
+        ) {
             this.lightDirectionsParam = lightDirectionsParam;
             this.lightColorsParam = lightColorsParam;
+            this.lightSpaceMatricesParam = lightSpaceMatricesParam;
         }
 
         public DirectionalLight this[int i]
@@ -39,8 +45,10 @@ namespace Kav
                 directions[i] = value.Direction;
                 colors[i] = value.Color.ToVector3() * value.Intensity;
                 intensities[i] = value.Intensity;
+                lightSpaceMatrices[i] = value.View * value.Projection;
                 lightDirectionsParam.SetValue(directions);
                 lightColorsParam.SetValue(colors);
+                lightSpaceMatricesParam.SetValue(lightSpaceMatrices);
             }
         }
     }

Effects/HLSL/DeferredPBREffect.fx

@@ -8,6 +8,7 @@ DECLARE_TEXTURE(gPosition, 0);
 DECLARE_TEXTURE(gAlbedo, 1);
 DECLARE_TEXTURE(gNormal, 2);
 DECLARE_TEXTURE(gMetallicRoughness, 3);
+DECLARE_CUBEMAP(shadowMap, 4);
 
 BEGIN_CONSTANTS
 
@@ -21,6 +22,8 @@ BEGIN_CONSTANTS
 
 MATRIX_CONSTANTS
 
+    float4x4 DirectionalLightMatrices[MAX_DIRECTIONAL_LIGHTS]  _ps(c137)   _cb(c137);
+
 END_CONSTANTS
 
 struct PixelInput
@@ -71,6 +74,63 @@ float GeometrySmith(float3 N, float3 V, float3 L, float roughness)
     return ggx1 * ggx2;
 }
 
+float3 ConvertCubeUVToXYZ(int index, float u, float v)
+{
+    float uc = 2.0 * u - 1.0;
+    float vc = 2.0 * v - 1.0;
+
+    if (index == 0) { return float3(1.0, vc, -uc); }
+    if (index == 1) { return float3(-1.0, vc, uc); }
+    if (index == 2) { return float3(uc, 1.0, -vc); }
+    if (index == 3) { return float3(uc, -1.0, vc); }
+    if (index == 4) { return float3(uc, vc, -1.0); }
+    if (index == 5) { return float3(-uc, vc, 1.0); }
+
+    return float3(1.0, 0.0, 0.5);
+}
+
+float ComputeShadow(float4 positionLightSpace, int directionalLightIndex)
+{
+    float bias = 0.001;
+
+    // maps to [-1, 1]
+    float3 projectionCoords = positionLightSpace.xyz / positionLightSpace.w;
+
+    float3 cubeMapSampleVector;
+
+    if (directionalLightIndex == 0)
+    {
+        cubeMapSampleVector = float3(1.0f, projectionCoords.y, -projectionCoords.x);
+    }
+    else if (directionalLightIndex == 1)
+    {
+        cubeMapSampleVector = float3(-1.0f, projectionCoords.y, projectionCoords.x);
+    }
+    else if (directionalLightIndex == 2)
+    {
+        cubeMapSampleVector = float3(projectionCoords.x, 1.0f, projectionCoords.y);
+    }
+    else if (directionalLightIndex == 3)
+    {
+        cubeMapSampleVector = float3(projectionCoords.x, -1.0f, -projectionCoords.y);
+    }
+    else if (directionalLightIndex == 4)
+    {
+        cubeMapSampleVector = float3(projectionCoords.x, projectionCoords.y, 1.0);
+    }
+    else
+    {
+        cubeMapSampleVector = float3(-projectionCoords.x, projectionCoords.y, -1.0);
+    }
+
+    float closestDepth = SAMPLE_CUBEMAP(shadowMap, cubeMapSampleVector).r;
+    float currentDepth = projectionCoords.z;
+
+    float shadow = currentDepth - bias > closestDepth ? 1.0 : 0.0;
+
+    return shadow;
+}
+
 float3 ComputeLight(
     float3 lightDir,
     float3 radiance,
@@ -79,7 +139,8 @@ float3 ComputeLight(
     float3 N,
     float3 albedo,
     float metallic,
-    float roughness
+    float roughness,
+    float shadow
 ) {
     float3 L = normalize(lightDir);
     float3 H = normalize(V + L);
@@ -98,7 +159,7 @@ float3 ComputeLight(
     kD *= 1.0 - metallic;
 
     float NdotL = max(dot(N, L), 0.0);
-    return (kD * albedo / PI + specular) * radiance * NdotL;
+    return (kD * albedo / PI + specular) * radiance * NdotL * shadow;
 }
 
 float4 ComputeColor(
@@ -124,16 +185,19 @@ float4 ComputeColor(
         float attenuation = 1.0 / (distance * distance);
         float3 radiance = PointLightColors[i] * attenuation;
 
-        Lo += ComputeLight(lightDir, radiance, F0, V, N, albedo, metallic, roughness);
+        Lo += ComputeLight(lightDir, radiance, F0, V, N, albedo, metallic, roughness, 1.0);
     }
 
     // directional light
-    for (int i = 0; i < MAX_DIRECTIONAL_LIGHTS; i++)
+    for (int i = 0; i < 1; i++)
     {
+        float4 positionLightSpace = mul(float4(worldPosition, 1.0), DirectionalLightMatrices[i]);
+        float shadow = ComputeShadow(positionLightSpace, i);
+
         float3 lightDir = DirectionalLightDirections[i];
         float3 radiance = DirectionalLightColors[i];
 
-        Lo += ComputeLight(lightDir, radiance, F0, V, N, albedo, metallic, roughness);
+        Lo += ComputeLight(lightDir, radiance, F0, V, N, albedo, metallic, roughness, (1.0 - shadow));
     }
 
     float3 ambient = float3(0.03, 0.03, 0.03) * albedo; // * AO;
@@ -148,13 +212,13 @@ float4 ComputeColor(
 
 float4 main_ps(PixelInput input) : SV_TARGET0
 {
-    float3 fragPosition = SAMPLE_TEXTURE(gPosition, input.TexCoord).rgb;
+    float3 worldPosition = SAMPLE_TEXTURE(gPosition, input.TexCoord).rgb;
     float3 normal = SAMPLE_TEXTURE(gNormal, input.TexCoord).xyz;
     float3 albedo = SAMPLE_TEXTURE(gAlbedo, input.TexCoord).rgb;
     float2 metallicRoughness = SAMPLE_TEXTURE(gMetallicRoughness, input.TexCoord).rg;
 
     return ComputeColor(
-        fragPosition,
+        worldPosition,
         normal,
         albedo,
         metallicRoughness.r,

Effects/HLSL/SimpleDepthEffect.fx

@@ -3,6 +3,8 @@
 BEGIN_CONSTANTS
 
     float4x4 ModelViewProjection    _vs(c0)             _cb(c0);
+    float near                      _vs(c4)             _cb(c4);
+    float far                       _vs(c5)             _cb(c5);
 
 MATRIX_CONSTANTS
 
@@ -16,21 +18,31 @@ struct VertexShaderInput
 struct VertexShaderOutput
 {
     float4 Position : SV_Position;
+    float Depth : TEXCOORD0;
 };
 
 VertexShaderOutput main_vs(VertexShaderInput input)
 {
     VertexShaderOutput output;
 
-    output.Position = mul(float4(input.Position.xyz, 1.0), ModelViewProjection);
+    output.Position = mul(input.Position, ModelViewProjection);
+
+    output.Depth = output.Position.z / output.Position.w;
+    output.Depth = (output.Depth * 0.5) + 0.5;
 
     return output;
 }
 
+float4 main_ps(VertexShaderOutput input) : SV_TARGET0
+{
+    return float4(input.Depth, 0.0, 0.0, 0.0);
+}
+
 Technique SimpleDepth
 {
     Pass
     {
         VertexShader = compile vs_3_0 main_vs();
+        PixelShader  = compile ps_3_0 main_ps();
     }
 }

Effects/PBREffect.cs

@@ -207,7 +207,8 @@ namespace Kav
 
             directionalLightCollection = new DirectionalLightCollection(
                 Parameters["LightDirections"],
-                Parameters["DirectionLightColors"]
+                Parameters["DirectionLightColors"],
+                Parameters["DirectionalLightMatrices"]
             );
         }
 
@@ -232,7 +233,8 @@ namespace Kav
 
             DirectionalLights = new DirectionalLightCollection(
                 Parameters["LightDirections"],
-                Parameters["DirectionLightColors"]
+                Parameters["DirectionLightColors"],
+                Parameters["DirectionalLightMatrices"]
             );
 
             for (int i = 0; i < MaxDirectionalLights; i++)

Effects/SimpleDepthEffect.cs

@@ -6,6 +6,8 @@ namespace Kav
     public class SimpleDepthEffect : Effect
     {
         EffectParameter modelViewProjectionParam;
+        EffectParameter nearParam;
+        EffectParameter farParam;
 
         Matrix model;
         Matrix view;
@@ -42,6 +44,10 @@ namespace Kav
                 dirtyFlags |= EffectDirtyFlags.WorldViewProj;
             }
         }
+
+        public float Near { get; set; }
+        public float Far { get; set; }
+
         public SimpleDepthEffect(GraphicsDevice graphicsDevice) : base(graphicsDevice, Resources.SimpleDepthEffect)
         {
             CacheEffectParameters();
@@ -58,11 +64,16 @@ namespace Kav
 
                 dirtyFlags &= ~EffectDirtyFlags.WorldViewProj;
             }
+
+            nearParam.SetValue(Near);
+            farParam.SetValue(Far);
         }
 
         private void CacheEffectParameters()
         {
             modelViewProjectionParam = Parameters["ModelViewProjection"];
+            nearParam = Parameters["near"];
+            farParam = Parameters["far"];
         }
     }
 }

Lights/DirectionalLight.cs

@@ -12,7 +12,7 @@ namespace Kav
         {
             get
             {
-                return Matrix.CreateLookAt(-Direction * 100f, Vector3.Zero, Vector3.Up);
+                return Matrix.CreateLookAt(Direction * 4.5f, Vector3.Zero, Vector3.Up);
             }
         }
 
@@ -20,7 +20,7 @@ namespace Kav
         {
             get
             {
-                return Matrix.CreateOrthographic(20f, 20f, 1f, 101f);
+                return Matrix.CreateOrthographic(20f, 20f, 1f, 7.5f);
             }
         }
 

Renderer.cs

@@ -10,7 +10,7 @@ namespace Kav
         private int RenderDimensionsX { get; }
         private int RenderDimensionsY { get; }
 
-        private RenderTarget2D DepthRenderTarget { get; }
+        private RenderTargetCube DirectionalLightDepthTarget { get; }
         private SimpleDepthEffect SimpleDepthEffect { get; }
 
         private RenderTarget2D gPosition { get; }
@@ -31,12 +31,11 @@ namespace Kav
             RenderDimensionsX = renderDimensionsX;
             RenderDimensionsY = renderDimensionsY;
 
-            DepthRenderTarget = new RenderTarget2D(
+            DirectionalLightDepthTarget = new RenderTargetCube(
                 GraphicsDevice,
-                renderDimensionsX,
-                renderDimensionsY,
+                1024,
                 false,
-                SurfaceFormat.HalfSingle, // unused
+                SurfaceFormat.Single,
                 DepthFormat.Depth24
             );
 
@@ -96,6 +95,13 @@ namespace Kav
 
             GraphicsDevice.SetRenderTarget(deferredRenderTarget);
             graphicsDevice.Clear(Color.White);
+
+            for (int i = 0; i < 6; i++)
+            {
+                GraphicsDevice.SetRenderTarget(DirectionalLightDepthTarget, (CubeMapFace) i);
+                GraphicsDevice.Clear(Color.White);
+            }
+
             GraphicsDevice.SetRenderTarget(null);
         }
 
@@ -105,6 +111,15 @@ namespace Kav
             IEnumerable<PointLight> pointLights,
             IEnumerable<DirectionalLight> directionalLights
         ) {
+            var directionalLightIndex = 0;
+
+            foreach (var directionalLight in directionalLights)
+            {
+                if (directionalLightIndex > 5) { break; }
+                ShadowMapRender(modelTransforms, directionalLight, (CubeMapFace) directionalLightIndex);
+                directionalLightIndex += 1;
+            }
+
             GraphicsDevice.SetRenderTargets(GBuffer);
             GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.DepthBuffer, Color.Black, 1f, 0);
             GraphicsDevice.DepthStencilState = DepthStencilState.Default;
@@ -150,6 +165,7 @@ namespace Kav
             DeferredPBREffect.GAlbedo = gAlbedo;
             DeferredPBREffect.GNormal = gNormal;
             DeferredPBREffect.GMetallicRoughness = gMetallicRoughness;
+            DeferredPBREffect.DirectionalShadowMap = DirectionalLightDepthTarget;
             DeferredPBREffect.EyePosition = Matrix.Invert(camera.View).Translation;
 
             int i = 0;
@@ -173,23 +189,18 @@ namespace Kav
             SpriteBatch.End();
         }
 
-        public void Render(
-            Camera camera, 
-            IEnumerable<(Model, Matrix)> modelTransforms, 
-            IEnumerable<PointLight> pointLights,
-            IEnumerable<DirectionalLight> directionalLights
-        ) {
-            Render(camera.View, camera.Projection, modelTransforms, pointLights, directionalLights);
-        }
-
         // for shadow mapping
-        public void DepthRender(IEnumerable<(Model, Matrix)> modelTransforms, DirectionalLight directionalLight)
+        public void ShadowMapRender(IEnumerable<(Model, Matrix)> modelTransforms, DirectionalLight directionalLight, CubeMapFace face)
         {
-            GraphicsDevice.SetRenderTarget(DepthRenderTarget);
-            GraphicsDevice.Clear(ClearOptions.DepthBuffer, Color.Black, 1, 0);
-
+            GraphicsDevice.SetRenderTarget(DirectionalLightDepthTarget, face);
+            GraphicsDevice.Clear(Color.White);
+            GraphicsDevice.DepthStencilState = DepthStencilState.Default;
+            GraphicsDevice.BlendState = BlendState.Opaque;
+            
             SimpleDepthEffect.View = directionalLight.View;
             SimpleDepthEffect.Projection = directionalLight.Projection;
+            SimpleDepthEffect.Near = 0.1f; // FIXME: this is a kludge
+            SimpleDepthEffect.Far = 200f;
 
             foreach (var (model, transform) in modelTransforms)
             {
@@ -220,6 +231,15 @@ namespace Kav
             }
         }
 
+        public void Render(
+            Camera camera, 
+            IEnumerable<(Model, Matrix)> modelTransforms, 
+            IEnumerable<PointLight> pointLights,
+            IEnumerable<DirectionalLight> directionalLights
+        ) {
+            Render(camera.View, camera.Projection, modelTransforms, pointLights, directionalLights);
+        }
+
         private void Render(
             Matrix view,
             Matrix projection,