Add request-level clear control for camera rendering

engine/include/XCEngine/Rendering/CameraRenderRequest.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <XCEngine/Rendering/RenderCameraData.h>
 #include <XCEngine/Rendering/RenderContext.h>
 #include <XCEngine/Rendering/RenderSurface.h>
 
@@ -17,6 +18,7 @@ struct CameraRenderRequest {
     RenderContext context;
     RenderSurface surface;
     float cameraDepth = 0.0f;
+    RenderClearFlags clearFlags = RenderClearFlags::All;
 
     bool IsValid() const {
         return scene != nullptr &&

engine/include/XCEngine/Rendering/RenderCameraData.h

@@ -9,12 +9,34 @@
 namespace XCEngine {
 namespace Rendering {
 
+enum class RenderClearFlags : uint8_t {
+    None = 0,
+    Color = 1 << 0,
+    Depth = 1 << 1,
+    All = (1 << 0) | (1 << 1)
+};
+
+constexpr RenderClearFlags operator|(RenderClearFlags lhs, RenderClearFlags rhs) {
+    return static_cast<RenderClearFlags>(
+        static_cast<uint8_t>(lhs) | static_cast<uint8_t>(rhs));
+}
+
+constexpr RenderClearFlags operator&(RenderClearFlags lhs, RenderClearFlags rhs) {
+    return static_cast<RenderClearFlags>(
+        static_cast<uint8_t>(lhs) & static_cast<uint8_t>(rhs));
+}
+
+constexpr bool HasRenderClearFlag(RenderClearFlags flags, RenderClearFlags flag) {
+    return static_cast<uint8_t>(flags & flag) != 0;
+}
+
 struct RenderCameraData {
     Math::Matrix4x4 view = Math::Matrix4x4::Identity();
     Math::Matrix4x4 projection = Math::Matrix4x4::Identity();
     Math::Matrix4x4 viewProjection = Math::Matrix4x4::Identity();
     Math::Vector3 worldPosition = Math::Vector3::Zero();
     Math::Color clearColor = Math::Color::Black();
+    RenderClearFlags clearFlags = RenderClearFlags::All;
     uint32_t viewportWidth = 0;
     uint32_t viewportHeight = 0;
 };

engine/src/Rendering/CameraRenderer.cpp

@@ -50,6 +50,7 @@ bool CameraRenderer::Render(
         return false;
     }
 
+    sceneData.cameraData.clearFlags = request.clearFlags;
     return m_pipeline->Render(request.context, request.surface, sceneData);
 }
 

engine/src/Rendering/Pipelines/BuiltinForwardPipeline.cpp

@@ -235,12 +235,15 @@ bool BuiltinForwardPipeline::Render(
         ? surface.GetClearColorOverride()
         : sceneData.cameraData.clearColor;
     const float clearValues[4] = { clearColor.r, clearColor.g, clearColor.b, clearColor.a };
-    for (RHI::RHIResourceView* renderTarget : renderTargets) {
-        if (renderTarget != nullptr) {
-            commandList->ClearRenderTarget(renderTarget, clearValues);
+    if (HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Color)) {
+        for (RHI::RHIResourceView* renderTarget : renderTargets) {
+            if (renderTarget != nullptr) {
+                commandList->ClearRenderTarget(renderTarget, clearValues);
+            }
         }
     }
-    if (surface.GetDepthAttachment() != nullptr) {
+    if (surface.GetDepthAttachment() != nullptr &&
+        HasRenderClearFlag(sceneData.cameraData.clearFlags, RenderClearFlags::Depth)) {
         commandList->ClearDepthStencil(surface.GetDepthAttachment(), 1.0f, 0);
     }
 

engine/src/Rendering/SceneRenderer.cpp

@@ -47,6 +47,7 @@ std::vector<CameraRenderRequest> SceneRenderer::BuildRenderRequests(
     request.context = context;
     request.surface = surface;
     request.cameraDepth = camera->GetDepth();
+    request.clearFlags = RenderClearFlags::All;
     requests.push_back(request);
     return requests;
 }