From 8c0a11d2e856f6e82221c1ea150b700bd7f5dddc Mon Sep 17 00:00:00 2001
From: atdunbg <atdunbg@qq.com>
Date: Wed, 23 Sep 2026 23:18:36 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20CSM=20=E8=BD=AF=E9=98=B4=E5=BD=B1?=
 =?UTF-8?q?=E2=80=94=E2=80=94sampler2DShadow=20=E7=A1=AC=E4=BB=B6=20PCF=20?=
 =?UTF-8?q?+=203=C3=973=20=E7=BA=B9=E7=B4=A0=20tap?=
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- 阴影采样器开启硬件深度比较（compareOp=eLess + linear filter）：
  单次采样 = 2×2 深度比较插值，clamp-to-border 白色语义不变
- ShadowFactor 改 3×3 纹素偏移 tap（等效 36 次比较），影中保留
  0.3 环境感并按 PCF 结果插值——阴影边缘软过渡，消除二值硬边锯齿
---
 Engine/src/Renderer/Passes/SceneGpu.cpp |  7 +++--
 shaders/simple_shader.frag              | 39 +++++++++++++++++--------
 2 files changed, 32 insertions(+), 14 deletions(-)

diff --git a/Engine/src/Renderer/Passes/SceneGpu.cpp b/Engine/src/Renderer/Passes/SceneGpu.cpp
index 2be4183..7edc676 100644
--- a/Engine/src/Renderer/Passes/SceneGpu.cpp
+++ b/Engine/src/Renderer/Passes/SceneGpu.cpp
@@ -103,7 +103,9 @@ namespace Engine::Passes
             ENGINE_FATAL("SceneGpu: failed to create shader objects");
         }
 
-        // 阴影采样器：clamp-to-border 白色 = 光视锥之外无阴影
+        // 阴影采样器：clamp-to-border 白色 = 光视锥外自动无阴影
+        //（省 shader 出界分支）；开启硬件深度比较（sampler2DShadow）
+        // ——单次采样即 2×2 PCF，配合 shader 3×3 tap 得软阴影
         vk::SamplerCreateInfo shadowSamplerInfo;
         shadowSamplerInfo.setMagFilter(vk::Filter::eLinear)
                          .setMinFilter(vk::Filter::eLinear)
@@ -113,7 +115,8 @@ namespace Engine::Passes
                          .setAddressModeW(vk::SamplerAddressMode::eClampToBorder)
                          .setBorderColor(vk::BorderColor::eFloatOpaqueWhite)
                          .setUnnormalizedCoordinates(VK_FALSE)
-                         .setCompareEnable(VK_FALSE);
+                         .setCompareEnable(VK_TRUE)
+                         .setCompareOp(vk::CompareOp::eLess);
         shadowSampler = device.GetDevice().createSampler(shadowSamplerInfo);
 
         // per-slot 描述符分配 + Set0 绑定（buffer 句柄全程稳定，不用重绑）
diff --git a/shaders/simple_shader.frag b/shaders/simple_shader.frag
index 043c1ea..61911d6 100644
--- a/shaders/simple_shader.frag
+++ b/shaders/simple_shader.frag
@@ -2,6 +2,7 @@
 
 const int MAX_LIGHTS = 4;
 const float PI = 3.14159265359;
+const int kCascadeRes = 1024;   // CSM 级联图边长（与引擎 SceneTypes.h 同步）
 
 struct Light {
     vec4 color;       // rgb = 颜色，a = 强度
@@ -43,16 +44,18 @@ layout(set = 1, binding = 5) uniform MaterialParams {
     vec4 factors;   // x = metallic 因子，y = roughness 因子
 } matParams;
 
-layout(set = 2, binding = 0) uniform sampler2D shadowMap0;   // CSM 级联 0（最近）
-layout(set = 2, binding = 1) uniform sampler2D shadowMap1;   // 级联 1
-layout(set = 2, binding = 2) uniform sampler2D shadowMap2;   // 级联 2（最远）
+// CSM 阴影（sampler2DShadow：单次采样 = 硬件 2×2 深度比较 PCF）
+layout(set = 2, binding = 0) uniform sampler2DShadow shadowMap0;   // CSM 级联 0（最近）
+layout(set = 2, binding = 1) uniform sampler2DShadow shadowMap1;   // 级联 1
+layout(set = 2, binding = 2) uniform sampler2DShadow shadowMap2;   // 级联 2（最远）
 layout(set = 2, binding = 3) uniform samplerCube irradianceMap;   // 漫反射环境光（IBL 阶段②）
 layout(set = 2, binding = 4) uniform samplerCube prefilteredMap;  // 镜面环境（mip 分 roughness，阶段③）
 layout(set = 2, binding = 5) uniform sampler2D brdfLut;           // BRDF 积分表 (NdotV, roughness) → (scale, bias)
 
-// 第 0 盏方向光（KeyLight）的 CSM 阴影因子：0.3 影中 / 1.0 受光。
-// 级联按视图深度选择；采样器均 clamp-to-border 白色：
-// 光视锥外自动 1.0（无阴影），省出界分支。
+// 第 0 盏方向光（KeyLight）的 CSM 阴影因子。
+// 级联按视图深度选择；3×3 纹素偏移采样（每 tap 硬件 2×2 PCF，
+// 等效 36 次比较）→ 软阴影边缘；采样器 clamp-to-border 白色：
+// 光视锥外自动 1.0（无阴影），省出界分支
 float ShadowFactor(vec3 N, float viewDepth) {
     int cascade = 2;
     for (int i = 0; i < 3; ++i) {
@@ -63,15 +66,27 @@ float ShadowFactor(vec3 N, float viewDepth) {
     vec3 proj = ls.xyz / ls.w;
     vec2 uv = proj.xy * 0.5 + 0.5;
 
-    float closest;
-    if (cascade == 0)      closest = texture(shadowMap0, uv).r;
-    else if (cascade == 1) closest = texture(shadowMap1, uv).r;
-    else                   closest = texture(shadowMap2, uv).r;
-
     vec3 L = normalize(-ubo.lights[0].direction.xyz);
     float bias = max(0.004 * (1.0 - dot(N, L)), 0.0012);
 
-    return (proj.z - bias > closest) ? 0.3 : 1.0;
+    float texel = 1.0 / float(kCascadeRes);   // 与引擎 kCascadeRes 同步
+    float shadow = 0.0;
+    for (int y = -1; y <= 1; ++y) {
+        for (int x = -1; x <= 1; ++x) {
+            float lit;
+            if (cascade == 0)
+                lit = texture(shadowMap0, vec3(uv + vec2(x, y) * texel,
+                                               proj.z - bias));
+            else if (cascade == 1)
+                lit = texture(shadowMap1, vec3(uv + vec2(x, y) * texel,
+                                               proj.z - bias));
+            else
+                lit = texture(shadowMap2, vec3(uv + vec2(x, y) * texel,
+                                               proj.z - bias));
+            shadow += mix(0.3, 1.0, lit);   // 影中保留 0.3 环境感
+        }
+    }
+    return shadow / 9.0;
 }
 
 // 法线贴图 → 世界空间法线（TBN 构建）。