basic directional light shadow mapping

Effects/DeferredPBREffect.cs

@@ -9,8 +9,11 @@ namespace Kav
         EffectParameter gAlbedoParam;
         EffectParameter gNormalParam;
         EffectParameter gMetallicRoughnessParam;
+        EffectParameter shadowMapParam;
 
         EffectParameter eyePositionParam;
+        EffectParameter lightSpaceMatrixParam;
+
         PointLightCollection pointLightCollection;
         DirectionalLightCollection directionalLightCollection;
 
@@ -18,8 +21,10 @@ namespace Kav
         public Texture2D GAlbedo { get; set; }
         public Texture2D GNormal { get; set; }
         public Texture2D GMetallicRoughness { get; set; }
+        public Texture2D ShadowMap { get; set; }
 
         public Vector3 EyePosition { get; set; }
+        public Matrix LightSpaceMatrix { get; set; }
 
         public int MaxPointLights { get; } = 64;
 
@@ -95,8 +100,10 @@ namespace Kav
             gAlbedoParam.SetValue(GAlbedo);
             gNormalParam.SetValue(GNormal);
             gMetallicRoughnessParam.SetValue(GMetallicRoughness);
+            shadowMapParam.SetValue(ShadowMap);
 
             eyePositionParam.SetValue(EyePosition);
+            lightSpaceMatrixParam.SetValue(LightSpaceMatrix);
         }
 
         void CacheEffectParameters()
@@ -105,8 +112,11 @@ namespace Kav
             gAlbedoParam = Parameters["gAlbedo"];
             gNormalParam = Parameters["gNormal"];
             gMetallicRoughnessParam = Parameters["gMetallicRoughness"];
+            shadowMapParam = Parameters["shadowMap"];
 
             eyePositionParam = Parameters["EyePosition"];
+
+            lightSpaceMatrixParam = Parameters["LightSpaceMatrix"];
         }
     }
 }

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_TEXTURE(shadowMap, 4); // TODO: one map per directional light
 
 BEGIN_CONSTANTS
 
@@ -21,6 +22,8 @@ BEGIN_CONSTANTS
 
 MATRIX_CONSTANTS
 
+    float4x4 LightSpaceMatrix                                  _ps(c137)   _cb(c137);
+
 END_CONSTANTS
 
 struct PixelInput
@@ -71,6 +74,24 @@ float GeometrySmith(float3 N, float3 V, float3 L, float roughness)
     return ggx1 * ggx2;
 }
 
+float ComputeShadow(float4 positionLightSpace)
+{
+    float bias = 0.01;
+
+    // maps to [-1, 1]
+    float3 projectionCoords = positionLightSpace.xyz / positionLightSpace.w;
+
+    // maps to [0, 1]
+    projectionCoords = (projectionCoords * 0.5) + 0.5;
+
+    float closestDepth = SAMPLE_TEXTURE(shadowMap, projectionCoords.xy).r;
+    float currentDepth = projectionCoords.z;
+
+    float shadow = currentDepth - bias > closestDepth ? 1.0 : 0.0;
+
+    return shadow;
+}
+
 float3 ComputeLight(
     float3 lightDir,
     float3 radiance,
@@ -79,7 +100,8 @@ 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 +120,7 @@ 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(
@@ -108,6 +130,9 @@ float4 ComputeColor(
     float metallic,
     float roughness
 ) {
+    float4 positionLightSpace = mul(float4(worldPosition, 1.0), LightSpaceMatrix);
+    float shadow = ComputeShadow(positionLightSpace);
+
     float3 V = normalize(EyePosition - worldPosition);
     float3 N = normalize(worldNormal);
 
@@ -124,7 +149,7 @@ 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
@@ -133,7 +158,7 @@ float4 ComputeColor(
         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 +173,13 @@ 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/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 * 100f, Vector3.Zero, Vector3.Up);
             }
         }
 

Renderer.cs

@@ -36,7 +36,7 @@ namespace Kav
                 renderDimensionsX,
                 renderDimensionsY,
                 false,
-                SurfaceFormat.HalfSingle, // unused
+                SurfaceFormat.Single,
                 DepthFormat.Depth24
             );
 
@@ -105,6 +105,13 @@ namespace Kav
             IEnumerable<PointLight> pointLights,
             IEnumerable<DirectionalLight> directionalLights
         ) {
+            foreach (var directionalLight in directionalLights)
+            {
+                DepthRender(modelTransforms, directionalLight);
+                DeferredPBREffect.LightSpaceMatrix = directionalLight.View * directionalLight.Projection;
+                break; // FIXME: this is a kludge
+            }
+
             GraphicsDevice.SetRenderTargets(GBuffer);
             GraphicsDevice.Clear(ClearOptions.Target | ClearOptions.DepthBuffer, Color.Black, 1f, 0);
             GraphicsDevice.DepthStencilState = DepthStencilState.Default;
@@ -150,6 +157,7 @@ namespace Kav
             DeferredPBREffect.GAlbedo = gAlbedo;
             DeferredPBREffect.GNormal = gNormal;
             DeferredPBREffect.GMetallicRoughness = gMetallicRoughness;
+            DeferredPBREffect.ShadowMap = DepthRenderTarget;
             DeferredPBREffect.EyePosition = Matrix.Invert(camera.View).Translation;
 
             int i = 0;
@@ -173,23 +181,18 @@ 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)
         {
             GraphicsDevice.SetRenderTarget(DepthRenderTarget);
-            GraphicsDevice.Clear(ClearOptions.DepthBuffer, Color.Black, 1, 0);
+            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 +223,15 @@ 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,