rendering: formalize main light shadow bias settings

engine/include/XCEngine/Rendering/FrameData/RenderSceneData.h

@@ -5,6 +5,7 @@
 #include <XCEngine/Core/Math/Vector4.h>
 #include <XCEngine/Rendering/FrameData/RenderCameraData.h>
 #include <XCEngine/Rendering/FrameData/RenderEnvironmentData.h>
+#include <XCEngine/Rendering/Shadow/DirectionalShadowSettings.h>
 #include <XCEngine/Rendering/FrameData/VisibleGaussianSplatItem.h>
 #include <XCEngine/Rendering/FrameData/VisibleRenderItem.h>
 #include <XCEngine/Rendering/FrameData/VisibleVolumeItem.h>
@@ -63,20 +64,23 @@ static_assert(
 
 struct RenderDirectionalShadowSamplingData {
     float enabled = 0.0f;
-    float receiverDepthBias = 0.0f;
-    float normalBiasScale = 0.0f;
-    float shadowStrength = 0.0f;
+    DirectionalShadowSamplingSettings settings = {};
 };
 
 static_assert(
     sizeof(RenderDirectionalShadowSamplingData) == sizeof(float) * 4u,
     "RenderDirectionalShadowSamplingData must stay float4-sized for GPU constant layout");
 
+struct RenderDirectionalShadowCasterBiasData {
+    DirectionalShadowCasterBiasSettings settings = {};
+};
+
 struct RenderDirectionalShadowData {
     bool enabled = false;
     Math::Matrix4x4 viewProjection = Math::Matrix4x4::Identity();
     RenderDirectionalShadowMapMetrics mapMetrics = {};
     RenderDirectionalShadowSamplingData sampling = {};
+    RenderDirectionalShadowCasterBiasData casterBias = {};
     RHI::RHIResourceView* shadowMap = nullptr;
 
     bool IsValid() const {

engine/include/XCEngine/Rendering/Passes/BuiltinDepthStylePassBase.h

@@ -171,6 +171,10 @@ private:
     ResolvedShaderPass ResolveSurfaceShaderPass(
         const RenderSceneData& sceneData,
         const Resources::Material* material) const;
+    Resources::MaterialRenderState ResolveEffectiveDepthRenderState(
+        const Resources::ShaderPass* shaderPass,
+        const Resources::Material* material,
+        const RenderSceneData& sceneData) const;
     bool TryBuildSupportedBindingPlan(
         const Resources::ShaderPass& shaderPass,
         BuiltinPassResourceBindingPlan& outPlan,

engine/include/XCEngine/Rendering/Planning/CameraRenderRequest.h

@@ -5,6 +5,7 @@
 #include <XCEngine/Rendering/RenderContext.h>
 #include <XCEngine/Rendering/RenderPass.h>
 #include <XCEngine/Rendering/RenderSurface.h>
+#include <XCEngine/Rendering/Shadow/DirectionalShadowSettings.h>
 
 #include <array>
 #include <cstdint>
@@ -131,6 +132,8 @@ struct DirectionalShadowRenderPlan {
     float texelWorldSize = 0.0f;
     float nearClipPlane = 0.1f;
     float farClipPlane = 0.0f;
+    DirectionalShadowSamplingSettings sampling = {};
+    DirectionalShadowCasterBiasSettings casterBias = {};
     uint32_t mapWidth = 0;
     uint32_t mapHeight = 0;
     RenderCameraData cameraData = {};

engine/include/XCEngine/Rendering/Planning/SceneRenderRequestPlanner.h

@@ -12,9 +12,9 @@ class Scene;
 
 namespace Rendering {
 
-// Planning-only knobs for fitting the single main-light shadow camera to the
-// current view. Receiver-side bias/filtering parameters live in runtime shadow
-// data and are not configured here.
+// Planner-owned knobs for the single main-light shadow, including both camera
+// fitting and the default sampling / caster bias values emitted into the
+// runtime shadow contract.
 struct DirectionalShadowPlanningSettings {
     uint32_t mapDimension = 1024u;
     float minFocusDistance = 5.0f;
@@ -24,6 +24,8 @@ struct DirectionalShadowPlanningSettings {
     float minDepthRange = 20.0f;
     float boundsPadding = 1.0f;
     float minDepthPadding = 2.0f;
+    DirectionalShadowSamplingSettings sampling = {};
+    DirectionalShadowCasterBiasSettings casterBias = {};
 };
 
 class SceneRenderRequestPlanner {

engine/include/XCEngine/Rendering/Shadow/DirectionalShadowSettings.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstdint>
+
+namespace XCEngine {
+namespace Rendering {
+
+struct DirectionalShadowSamplingSettings {
+    float receiverDepthBias = 0.0015f;
+    float normalBiasScale = 1.5f;
+    float shadowStrength = 0.85f;
+};
+
+struct DirectionalShadowCasterBiasSettings {
+    float depthBiasFactor = 1.0f;
+    int32_t depthBiasUnits = 2;
+};
+
+} // namespace Rendering
+} // namespace XCEngine