ADD: aspect ratio preserving part 1-add constants

src/core/config.h

@@ -11,6 +11,7 @@ inline constexpr bool kUseValidationLayers = true;
 // - Default: disabled to avoid noise and I/O at shutdown.
 // - Enable at runtime by setting environment variable `VE_VMA_DEBUG=1`.
 #include <cstdlib>
+#include <cstdint>
 inline constexpr bool kEnableVmaDebugByDefault = false;
 inline bool vmaDebugEnabled()
 {
@@ -23,6 +24,12 @@ inline bool vmaDebugEnabled()
     return kEnableVmaDebugByDefault;
 }
 
+// Fixed logical render resolution for letterboxed viewport.
+// Internal rendering and camera aspect will target this size
+// even when the window/swapchain size changes.
+inline constexpr uint32_t kRenderWidth  = 1920;
+inline constexpr uint32_t kRenderHeight = 1080;
+
 // Shadow mapping configuration
 inline constexpr int kShadowCascadeCount = 4;
 // Maximum shadow distance for CSM in view-space units

src/core/context.h

@@ -69,6 +69,7 @@ public:
 
     // Frequently used values
     VkExtent2D drawExtent{};
+    VkExtent2D logicalRenderExtent{};
 
     // Optional convenience content pointers (moved to AssetManager for meshes)
 
@@ -95,6 +96,7 @@ public:
     const GPUSceneData& getSceneData() const;
     const DrawContext& getMainDrawContext() const;
     VkExtent2D getDrawExtent() const { return drawExtent; }
+    VkExtent2D getLogicalRenderExtent() const { return logicalRenderExtent; }
     AssetManager* getAssets() const { return assets; }
     // Convenience alias (singular) requested
     AssetManager* getAsset() const { return assets; }

src/core/device/swapchain.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <core/types.h>
+#include <core/config.h>
 
 class ResourceManager;
 class DeviceManager;
@@ -42,7 +43,7 @@ private:
     VkSwapchainKHR _swapchain = nullptr;
     VkFormat _swapchainImageFormat = {};
     VkExtent2D _swapchainExtent = {};
-    VkExtent2D _windowExtent{1920, 1080};
+    VkExtent2D _windowExtent{kRenderWidth, kRenderHeight};
 
     std::vector<VkImage> _swapchainImages;
     std::vector<VkImageView> _swapchainImageViews;

src/core/engine.cpp

@@ -145,6 +145,10 @@ void VulkanEngine::init()
     // We initialize SDL and create a window with it.
     SDL_Init(SDL_INIT_VIDEO);
 
+    // Initialize fixed logical render resolution for the engine.
+    _logicalRenderExtent.width = kRenderWidth;
+    _logicalRenderExtent.height = kRenderHeight;
+
     constexpr auto window_flags = static_cast<SDL_WindowFlags>(SDL_WINDOW_VULKAN | SDL_WINDOW_RESIZABLE);
 
     _swapchainManager = std::make_unique<SwapchainManager>();
@@ -182,6 +186,7 @@ void VulkanEngine::init()
         };
         _context->descriptors->init(_deviceManager->device(), 10, sizes);
     }
+    _context->logicalRenderExtent = _logicalRenderExtent;
 
     _swapchainManager->init(_deviceManager.get(), _resourceManager.get());
     _swapchainManager->init_swapchain();

src/core/engine.h

@@ -84,6 +84,7 @@ public:
     FrameResources &get_current_frame() { return _frames[_frameNumber % FRAME_OVERLAP]; };
 
 	VkExtent2D _drawExtent;
+    VkExtent2D _logicalRenderExtent{};
 	float renderScale = 1.f;
 
     std::unique_ptr<DescriptorManager> _descriptorManager;