initial soft shadow implementation

Effects/DeferredPBR_DirectionalLightEffect.cs

@@ -22,6 +22,8 @@ namespace Kav
 
         EffectParameter cascadeFarPlanesParam;
 
+        EffectParameter shadowMapSizeParam;
+
         EffectParameter lightSpaceMatrixOneParam;
         EffectParameter lightSpaceMatrixTwoParam;
         EffectParameter lightSpaceMatrixThreeParam;
@@ -46,6 +48,8 @@ namespace Kav
 
         public readonly float[] CascadeFarPlanes;
 
+        public int ShadowMapSize { get; set; }
+
         public Matrix LightSpaceMatrixOne { get; set; }
         public Matrix LightSpaceMatrixTwo { get; set; }
         public Matrix LightSpaceMatrixThree { get; set; }
@@ -82,6 +86,8 @@ namespace Kav
                 CascadeFarPlanes[i] = cloneSource.CascadeFarPlanes[i];
             }
 
+            ShadowMapSize = cloneSource.ShadowMapSize;
+
             LightSpaceMatrixOne = cloneSource.LightSpaceMatrixOne;
             LightSpaceMatrixTwo = cloneSource.LightSpaceMatrixTwo;
             LightSpaceMatrixThree = cloneSource.LightSpaceMatrixThree;
@@ -113,6 +119,7 @@ namespace Kav
             directionalLightColorParam.SetValue(DirectionalLightColor);
 
             cascadeFarPlanesParam.SetValue(CascadeFarPlanes);
+            shadowMapSizeParam.SetValue(ShadowMapSize);
 
             lightSpaceMatrixOneParam.SetValue(LightSpaceMatrixOne);
             lightSpaceMatrixTwoParam.SetValue(LightSpaceMatrixTwo);
@@ -141,6 +148,8 @@ namespace Kav
 
             cascadeFarPlanesParam          = Parameters["CascadeFarPlanes"];
 
+            shadowMapSizeParam             = Parameters["ShadowMapSize"];
+
             lightSpaceMatrixOneParam       = Parameters["LightSpaceMatrixOne"];
             lightSpaceMatrixTwoParam       = Parameters["LightSpaceMatrixTwo"];
             lightSpaceMatrixThreeParam     = Parameters["LightSpaceMatrixThree"];

Effects/HLSL/DeferredPBR_DirectionalLightEffect.fx

@@ -21,18 +21,40 @@ BEGIN_CONSTANTS
 
     float CascadeFarPlanes[NUM_SHADOW_CASCADES]                _ps(c3)    _cb(c3);
 
+    float ShadowMapSize                                        _ps(c7)    _cb(c7);
+
 MATRIX_CONSTANTS
 
-    float4x4 LightSpaceMatrixOne                               _ps(c7)    _cb(c7);
+    float4x4 LightSpaceMatrixOne                               _ps(c8)    _cb(c8);
-    float4x4 LightSpaceMatrixTwo                               _ps(c11)   _cb(c11);
+    float4x4 LightSpaceMatrixTwo                               _ps(c12)   _cb(c12);
-    float4x4 LightSpaceMatrixThree                             _ps(c15)   _cb(c15);
+    float4x4 LightSpaceMatrixThree                             _ps(c16)   _cb(c16);
-    float4x4 LightSpaceMatrixFour                              _ps(c19)   _cb(c19);
+    float4x4 LightSpaceMatrixFour                              _ps(c20)   _cb(c20);
 
     // used to select shadow cascade
-    float4x4 ViewMatrix                                        _ps(c23)   _cb(c23);
+    float4x4 ViewMatrix                                        _ps(c24)   _cb(c24);
 
 END_CONSTANTS
 
+static float2 poissonDisk[16] = 
+{
+   float2( -0.94201624, -0.39906216 ), 
+   float2( 0.94558609, -0.76890725 ), 
+   float2( -0.094184101, -0.92938870 ), 
+   float2( 0.34495938, 0.29387760 ), 
+   float2( -0.91588581, 0.45771432 ), 
+   float2( -0.81544232, -0.87912464 ), 
+   float2( -0.38277543, 0.27676845 ), 
+   float2( 0.97484398, 0.75648379 ), 
+   float2( 0.44323325, -0.97511554 ), 
+   float2( 0.53742981, -0.47373420 ), 
+   float2( -0.26496911, -0.41893023 ), 
+   float2( 0.79197514, 0.19090188 ), 
+   float2( -0.24188840, 0.99706507 ), 
+   float2( -0.81409955, 0.91437590 ), 
+   float2( 0.19984126, 0.78641367 ), 
+   float2( 0.14383161, -0.14100790 ) 
+};
+
 struct VertexInput
 {
     float4 Position : POSITION;
@@ -57,6 +79,30 @@ PixelInput main_vs(VertexInput input)
 
 // Pixel Shader
 
+// Returns a random number based on a vec3 and an int.
+float random(float3 seed, int i){
+	float4 seed4 = float4(seed, i);
+	float dot_product = dot(seed4, float4(12.9898,78.233,45.164,94.673));
+	return frac(sin(dot_product) * 43758.5453);
+}
+
+float PoissonCoord(sampler shadowMap, float3 worldPosition, float2 texCoord, float fragmentDepth, float bias)
+{
+    float visibility = 1.0;
+
+    for (int i = 0; i < 16; i++)
+    {
+        int index = int(16.0 * random(floor(worldPosition * 1000.0), i)) % 16;
+
+        if (tex2D(shadowMap, texCoord + poissonDisk[i] / 700.0).r < fragmentDepth - bias)
+        {
+            visibility -= 0.2;
+        }
+    }
+
+    return visibility;
+}
+
 float ComputeShadow(float3 positionWorldSpace, float3 N, float3 L)
 {
     float bias = 0.005 * tan(acos(dot(N, L)));
@@ -104,42 +150,58 @@ float ComputeShadow(float3 positionWorldSpace, float3 N, float3 L)
     projectionCoords.y *= -1;
     // in XNA clip z is 0 to 1 already
 
-    float inc = 1.0 / 1024.0;
+    if (projectionCoords.z > 1.0)
+    {
+        return 1.0;
+    }
+
+    float inc = 1.0 / ShadowMapSize; // TODO: shadow map size uniform
+
+    // PCF + Poisson soft shadows
+    float visibility = 0.0;
+    // for (int row = -1; row <= 1; row++)
+    // {
+    //     for (int col = -1; col <= 1; col++)
+    //     {
+    //         if (shadowCascadeIndex == 0)
+    //         {
+    //             visibility += PoissonCoord(SAMPLER(shadowMapOne), positionWorldSpace, projectionCoords.xy + float2(row, col) * inc, projectionCoords.z, bias);
+    //         }
+    //         else if (shadowCascadeIndex == 1)
+    //         {
+    //             visibility += PoissonCoord(SAMPLER(shadowMapTwo), positionWorldSpace, projectionCoords.xy + float2(row, col) * inc, projectionCoords.z, bias);
+    //         }
+    //         else if (shadowCascadeIndex == 2)
+    //         {
+    //             visibility += PoissonCoord(SAMPLER(shadowMapThree), positionWorldSpace, projectionCoords.xy + float2(row, col) * inc, projectionCoords.z, bias);
+    //         }
+    //         else
+    //         {
+    //             visibility += PoissonCoord(SAMPLER(shadowMapFour), positionWorldSpace, projectionCoords.xy + float2(row, col) * inc, projectionCoords.z, bias);
+    //         }
+    //     }
+    // }
+
+    // visibility /= 9.0;
 
-    float shadowFactor = 0;
-    for (int row = -1; row <= 1; row++)
-    {
-        for (int col = -1; col <= 1; col++)
-        {
-            float closestDepth;
     if (shadowCascadeIndex == 0)
     {
-                closestDepth = SAMPLE_TEXTURE(shadowMapOne, projectionCoords.xy + float2(row, col) * inc).r;
+        visibility = PoissonCoord(SAMPLER(shadowMapOne), positionWorldSpace, projectionCoords.xy, projectionCoords.z, bias);
     }
     else if (shadowCascadeIndex == 1)
     {
-                closestDepth = SAMPLE_TEXTURE(shadowMapTwo, projectionCoords.xy + float2(row, col) * inc).r;
+        visibility = PoissonCoord(SAMPLER(shadowMapTwo), positionWorldSpace, projectionCoords.xy, projectionCoords.z, bias);
     }
     else if (shadowCascadeIndex == 2)
     {
-                closestDepth = SAMPLE_TEXTURE(shadowMapThree, projectionCoords.xy + float2(row, col) * inc).r;
+        visibility = PoissonCoord(SAMPLER(shadowMapThree), positionWorldSpace, projectionCoords.xy, projectionCoords.z, bias);
     }
     else
     {
-                closestDepth = SAMPLE_TEXTURE(shadowMapFour, projectionCoords.xy + float2(row, col) * inc).r;
+        visibility = PoissonCoord(SAMPLER(shadowMapFour), positionWorldSpace, projectionCoords.xy, projectionCoords.z, bias);
-            }
-            shadowFactor += projectionCoords.z - bias > closestDepth ? 1.0 : 0.0;
-        }
     }
 
-    shadowFactor /= 9.0;
+    return visibility;
-
-    if (projectionCoords.z > 1.0)
-    {
-        shadowFactor = 1.0;
-    }
-
-    return shadowFactor;
 }
 
 float4 ComputeColor(
@@ -159,7 +221,7 @@ float4 ComputeColor(
     float3 radiance = DirectionalLightColor;
 
     float shadow = ComputeShadow(worldPosition, N, L);
-    float3 color = ComputeLight(L, radiance, F0, V, N, albedo, metallic, roughness, (1.0 - shadow));
+    float3 color = ComputeLight(L, radiance, F0, V, N, albedo, metallic, roughness, shadow);
 
     return float4(color, 1.0);
 }

Effects/HLSL/Lighting.fxh

@@ -49,7 +49,7 @@ float3 ComputeLight(
     float3 albedo,
     float metallic,
     float roughness,
-    float shadow
+    float visibility
 ) {
     float3 H = normalize(V + L);
 
@@ -67,5 +67,5 @@ float3 ComputeLight(
     kD *= 1.0 - metallic;
 
     float NdotL = max(dot(N, L), 0.0);
-    return (kD * albedo / PI + specular) * radiance * NdotL * shadow;
+    return (kD * albedo / PI + specular) * radiance * NdotL * visibility;
 }

Effects/HLSL/Macros.fxh

@@ -54,4 +54,5 @@
 #define SAMPLE_TEXTURE(Name, texCoord)  tex2D(Name##Sampler, texCoord)
 #define SAMPLE_CUBEMAP(Name, texCoord)  texCUBE(Name##Sampler, texCoord)
 #define SAMPLE_CUBEMAP_LOD(Name, texCoord)  texCUBElod(Name##Sampler, texCoord)
+#define SAMPLER(Name) Name##Sampler
 #endif

Renderer.cs

@@ -7,6 +7,7 @@ namespace Kav
     public class Renderer
     {
         private const int MAX_SHADOW_CASCADES = 4;
+        private int ShadowMapSize { get; }
 
         private GraphicsDevice GraphicsDevice { get; }
         private int RenderDimensionsX { get; }
@@ -34,12 +35,19 @@ namespace Kav
 
         private SpriteBatch SpriteBatch { get; }
 
-        public Renderer(GraphicsDevice graphicsDevice, int renderDimensionsX, int renderDimensionsY, int numShadowCascades)
+        public Renderer(
-        {
+            GraphicsDevice graphicsDevice,
+            int renderDimensionsX,
+            int renderDimensionsY,
+            int numShadowCascades,
+            int shadowMapSize
+        ) {
             GraphicsDevice = graphicsDevice;
             RenderDimensionsX = renderDimensionsX;
             RenderDimensionsY = renderDimensionsY;
 
+            ShadowMapSize = shadowMapSize;
+
             NumShadowCascades = (int)MathHelper.Clamp(numShadowCascades, 1, MAX_SHADOW_CASCADES);
             ShadowRenderTargets = new RenderTarget2D[numShadowCascades];
 
@@ -47,8 +55,8 @@ namespace Kav
             {
                 ShadowRenderTargets[i] = new RenderTarget2D(
                     GraphicsDevice,
-                    1024,
+                    ShadowMapSize,
-                    1024,
+                    ShadowMapSize,
                     false,
                     SurfaceFormat.Single,
                     DepthFormat.Depth24
@@ -126,6 +134,8 @@ namespace Kav
             DeferredPointLightEffect = new DeferredPBR_PointLightEffect(GraphicsDevice);
             DeferredDirectionalLightEffect = new DeferredPBR_DirectionalLightEffect(GraphicsDevice);
 
+            DeferredDirectionalLightEffect.ShadowMapSize = ShadowMapSize;
+            
             FullscreenTriangle = new VertexBuffer(GraphicsDevice, typeof(VertexPositionTexture), 3, BufferUsage.WriteOnly);
             FullscreenTriangle.SetData(new VertexPositionTexture[3] {
                 new VertexPositionTexture(new Vector3(-1, -3, 0), new Vector2(0, 2)),