fix: editor camera draw distance 100m -> 10km (UE semantics)

UE's far clip is effectively unlimited and shadow distance is an
independent parameter. Split kCameraFar (main projection, 10km) from
kShadowDistance (cascade splits, unchanged 100m) so distant geometry
is no longer clipped while shadow quality stays bit-identical.
Main projection now references the shared constants instead of
duplicated literals.

Engine/src/Renderer/SceneRenderer.cpp

@@ -31,9 +31,14 @@ namespace Engine
 
     namespace
     {
-        // 相机裁剪范围（与 BuildFrame 中 GetProjection 的参数一致）
+        // 相机裁剪范围（UE 编辑器视口语义：near = 10cm；far 拉远到
+        // "无限"级——UE 的 far clip 默认就是不裁剪，深度精度由 near 主导，
+        // far 取多大都不损近处精度）。阴影距离独立（UE DirectionalLight
+        // 的 shadow distance 同构）：级联分割只覆盖 kShadowDistance，
+        // 更远无阴影，避免级联跟着 far 拉爆近处阴影分辨率
         constexpr f32 kCameraNear = 0.1f;
-        constexpr f32 kCameraFar = 100.0f;
+        constexpr f32 kCameraFar = 10000.0f;
+        constexpr f32 kShadowDistance = 100.0f;
         // 实用分割插值因子（0=均匀，1=对数；0.6 是业界常用值）
         constexpr f32 kCascadeLambda = 0.6f;
 
@@ -170,11 +175,12 @@ namespace Engine
         constexpr u32 N = kMaxCascades;
 
         // ---- 1. 实用分割：均匀与对数分割按 λ 插值（视图深度，正值）----
+        //（分割覆盖 [near, kShadowDistance]；kCameraFar 只管主投影裁剪）
         f32 splits[N];
         for (u32 i = 1; i <= N; ++i) {
             const f32 t = static_cast<f32>(i) / N;
-            const f32 uniform = kCameraNear + (kCameraFar - kCameraNear) * t;
-            const f32 log = kCameraNear * glm::pow(kCameraFar / kCameraNear, t);
+            const f32 uniform = kCameraNear + (kShadowDistance - kCameraNear) * t;
+            const f32 log = kCameraNear * glm::pow(kShadowDistance / kCameraNear, t);
             splits[i - 1] = glm::mix(uniform, log, kCascadeLambda);
         }
         for (u32 c = 0; c < N; ++c) {
@@ -199,6 +205,10 @@ namespace Engine
         for (u32 c = 0; c < N; ++c) {
             const f32 d0 = (c == 0) ? kCameraNear : splits[c - 1];
             const f32 d1 = splits[c];
+            // 视图深度 → 视锥棱边参数：棱边上 z_view 线性（near/far 角点
+            // 都在各自平面上），farC 反投影自主投影 far 面，故 t 相对
+            // kCameraFar 归一；splits 只覆盖 [near, kShadowDistance]，
+            // t 必然远小于 1 → 自然截出阴影范围内的切片
             const f32 t0 = (d0 - kCameraNear) / (kCameraFar - kCameraNear);
             const f32 t1 = (d1 - kCameraNear) / (kCameraFar - kCameraNear);
 
@@ -285,7 +295,7 @@ namespace Engine
         const f32 aspect = static_cast<f32>(targetExtent.width) /
                            static_cast<f32>(targetExtent.height);
         ubo.view = camera->GetView(*camTransform);
-        ubo.proj = camera->GetProjection(aspect, 0.1f, 100.0f);
+        ubo.proj = camera->GetProjection(aspect, kCameraNear, kCameraFar);
 
         // 未抖动投影：velocity 的当前帧 clip 位置用它（抖动不能进 velocity）
         ubo.projNoJitter = ubo.proj;