ADD: CSM half-working

src/core/config.h

@@ -6,3 +6,14 @@ inline constexpr bool kUseValidationLayers = false;
 #else
 inline constexpr bool kUseValidationLayers = true;
 #endif
+
+// Shadow mapping configuration
+inline constexpr int kShadowCascadeCount = 4;
+// Maximum shadow distance for CSM in view-space units
+inline constexpr float kShadowCSMFar = 50.0f;
+// Shadow map resolution used for stabilization (texel snapping). Must match actual image size.
+inline constexpr float kShadowMapResolution = 2048.0f;
+// Extra XY expansion for cascade footprint (safety against FOV/aspect changes)
+inline constexpr float kShadowCascadeRadiusScale = 1.15f;
+// Additive XY margin in world units (light-space) beyond scaled radius
+inline constexpr float kShadowCascadeRadiusMargin = 10.0f;

src/core/vk_descriptors.cpp

@@ -1,10 +1,10 @@
 #include <core/vk_descriptors.h>
 
-void DescriptorLayoutBuilder::add_binding(uint32_t binding, VkDescriptorType type)
+void DescriptorLayoutBuilder::add_binding(uint32_t binding, VkDescriptorType type, uint32_t count)
 {
     VkDescriptorSetLayoutBinding newbind{};
     newbind.binding = binding;
-    newbind.descriptorCount = 1;
+    newbind.descriptorCount = count;
     newbind.descriptorType = type;
 
     bindings.push_back(newbind);

src/core/vk_descriptors.h

@@ -7,7 +7,7 @@ struct DescriptorLayoutBuilder
 {
     std::vector<VkDescriptorSetLayoutBinding> bindings;
 
-    void add_binding(uint32_t binding, VkDescriptorType type);
+    void add_binding(uint32_t binding, VkDescriptorType type, uint32_t count = 1);
 
     void clear();
 

src/core/vk_engine.cpp

@@ -12,6 +12,8 @@
 
 #include <chrono>
 #include <thread>
+#include <span>
+#include <array>
 
 #include "render/vk_pipelines.h"
 #include <iostream>
@@ -31,6 +33,7 @@
 #include "vk_resource.h"
 #include "engine_context.h"
 #include "core/vk_pipeline_manager.h"
+#include "core/config.h"
 
 VulkanEngine *loadedEngine = nullptr;
 
@@ -314,9 +317,14 @@ void VulkanEngine::draw()
         RGImageHandle hGBufferAlbedo = _renderGraph->import_gbuffer_albedo();
         RGImageHandle hSwapchain = _renderGraph->import_swapchain_image(swapchainImageIndex);
 
-        // Create a transient shadow depth target (fixed resolution for now)
+        // Create transient depth targets for cascaded shadow maps
         const VkExtent2D shadowExtent{2048, 2048};
-        RGImageHandle hShadow = _renderGraph->create_depth_image("shadow.depth", shadowExtent, VK_FORMAT_D32_SFLOAT);
+        std::array<RGImageHandle, kShadowCascadeCount> hShadowCascades{};
+        for (int i = 0; i < kShadowCascadeCount; ++i)
+        {
+            std::string name = std::string("shadow.cascade.") + std::to_string(i);
+            hShadowCascades[i] = _renderGraph->create_depth_image(name.c_str(), shadowExtent, VK_FORMAT_D32_SFLOAT);
+        }
 
         _resourceManager->register_upload_pass(*_renderGraph, get_current_frame());
 
@@ -331,7 +339,7 @@ void VulkanEngine::draw()
             }
             if (auto *shadow = _renderPassManager->getPass<ShadowPass>())
             {
-                shadow->register_graph(_renderGraph.get(), hShadow, shadowExtent);
+                shadow->register_graph(_renderGraph.get(), std::span<RGImageHandle>(hShadowCascades.data(), hShadowCascades.size()), shadowExtent);
             }
             if (auto *geometry = _renderPassManager->getPass<GeometryPass>())
             {
@@ -339,7 +347,8 @@ void VulkanEngine::draw()
             }
             if (auto *lighting = _renderPassManager->getPass<LightingPass>())
             {
-                lighting->register_graph(_renderGraph.get(), hDraw, hGBufferPosition, hGBufferNormal, hGBufferAlbedo, hShadow);
+                lighting->register_graph(_renderGraph.get(), hDraw, hGBufferPosition, hGBufferNormal, hGBufferAlbedo,
+                                         std::span<RGImageHandle>(hShadowCascades.data(), hShadowCascades.size()));
             }
             if (auto *transparent = _renderPassManager->getPass<TransparentPass>())
             {

src/core/vk_sampler_manager.cpp

@@ -28,6 +28,15 @@ void SamplerManager::init(DeviceManager *deviceManager)
     sampl.magFilter = VK_FILTER_LINEAR;
     sampl.minFilter = VK_FILTER_LINEAR;
     vkCreateSampler(_deviceManager->device(), &sampl, nullptr, &_defaultSamplerLinear);
+
+    // Shadow linear clamp sampler (border=white)
+    VkSamplerCreateInfo sh = sampl;
+    sh.addressModeU = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
+    sh.addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
+    sh.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_BORDER;
+    sh.compareEnable = VK_FALSE; // manual PCF
+    sh.borderColor = VK_BORDER_COLOR_FLOAT_OPAQUE_WHITE;
+    vkCreateSampler(_deviceManager->device(), &sh, nullptr, &_shadowLinearClamp);
 }
 
 void SamplerManager::cleanup()
@@ -44,4 +53,9 @@ void SamplerManager::cleanup()
         vkDestroySampler(_deviceManager->device(), _defaultSamplerLinear, nullptr);
         _defaultSamplerLinear = VK_NULL_HANDLE;
     }
+    if (_shadowLinearClamp)
+    {
+        vkDestroySampler(_deviceManager->device(), _shadowLinearClamp, nullptr);
+        _shadowLinearClamp = VK_NULL_HANDLE;
+    }
 }

src/core/vk_sampler_manager.h

@@ -13,10 +13,11 @@ public:
 
     VkSampler defaultLinear() const { return _defaultSamplerLinear; }
     VkSampler defaultNearest() const { return _defaultSamplerNearest; }
+    VkSampler shadowLinearClamp() const { return _shadowLinearClamp; }
 
 private:
     DeviceManager *_deviceManager = nullptr;
     VkSampler _defaultSamplerLinear = VK_NULL_HANDLE;
     VkSampler _defaultSamplerNearest = VK_NULL_HANDLE;
+    VkSampler _shadowLinearClamp = VK_NULL_HANDLE;
 };
-

src/core/vk_types.h

@@ -71,10 +71,14 @@ struct GPUSceneData {
     glm::mat4 view;
     glm::mat4 proj;
     glm::mat4 viewproj;
-    glm::mat4 lightViewProj;
+    glm::mat4 lightViewProj; // legacy single-shadow; kept for transition
     glm::vec4 ambientColor;
     glm::vec4 sunlightDirection; // w for sun power
     glm::vec4 sunlightColor;
+
+    // CSM data (unused by current shaders until wired)
+    glm::mat4 lightViewProjCascades[4];
+    glm::vec4 cascadeSplitsView;
 };
 
 enum class MaterialPass :uint8_t {