feat: depth buffer + 3D model matrix — rotating cube now looks correct

- Depth image (D32_SFLOAT) + image view created in VulkanSwapchain
- VkPipelineDepthStencilStateCreateInfo: depth test + write enabled, CompareOp=Less
- Push constant changed from float angle (4B) to mat4 model (64B)
- 3D rotation: RotateY * RotateX in renderer, applied via push constant
- Vertex shader: gl_Position = vp * model * vec4(pos, 1.0)
- Depth attachment in VkRenderingInfo + depth clear (1.0)
- Depth image layout transition (Undefined → DepthStencilAttachmentOptimal)
- New Vulkan functions: vkCreateImage, vkDestroyImage, vkGetImageMemoryRequirements, vkBindImageMemory
- New structs: VkPipelineDepthStencilStateCreateInfo, VkStencilOpState, VkImageCreateInfo
- New enums: VkCompareOp, VkImageType, VkImageTiling
- 0 validation errors

src/Engine.Graphics.Vulkan/Shaders/triangle.vert

@@ -10,18 +10,11 @@ layout(row_major, set = 0, binding = 0) uniform CameraUBO {
     mat4 vp;
 };
 
-layout(push_constant) uniform PC {
-    float angle;
+layout(row_major, push_constant) uniform PC {
+    mat4 model;
 } pc;
 
 void main() {
-    float c = cos(pc.angle);
-    float s = sin(pc.angle);
-    vec3 rotated = vec3(
-        inPosition.x * c - inPosition.y * s,
-        inPosition.x * s + inPosition.y * c,
-        inPosition.z
-    );
-    gl_Position = vp * vec4(rotated, 1.0);
+    gl_Position = vp * pc.model * vec4(inPosition, 1.0);
     fragColor = inColor;
 }

src/Engine.Graphics.Vulkan/Vk.cs

@@ -47,6 +47,10 @@ internal static unsafe class Vk
     public delegate VkResult VkGetFenceStatus(VkDevice device, VkFence fence);
     public delegate VkResult VkCreateBuffer(VkDevice device, VkBufferCreateInfo* pCreateInfo, nint pAllocator, VkBuffer* pBuffer);
     public delegate void VkDestroyBuffer(VkDevice device, VkBuffer buffer, nint pAllocator);
+    public delegate VkResult VkCreateImage(VkDevice device, VkImageCreateInfo* pCreateInfo, nint pAllocator, VkImage* pImage);
+    public delegate void VkDestroyImage(VkDevice device, VkImage image, nint pAllocator);
+    public delegate void VkGetImageMemoryRequirements(VkDevice device, VkImage image, VkMemoryRequirements* pMemoryRequirements);
+    public delegate VkResult VkBindImageMemory(VkDevice device, VkImage image, VkDeviceMemory memory, ulong memoryOffset);
     public delegate VkResult VkAllocateMemory(VkDevice device, VkMemoryAllocateInfo* pAllocateInfo, nint pAllocator, VkDeviceMemory* pMemory);
     public delegate void VkFreeMemory(VkDevice device, VkDeviceMemory memory, nint pAllocator);
     public delegate VkResult VkBindBufferMemory(VkDevice device, VkBuffer buffer, VkDeviceMemory memory, ulong memoryOffset);
@@ -124,6 +128,10 @@ internal static unsafe class Vk
     public static VkGetFenceStatus vkGetFenceStatus;
     public static VkCreateBuffer vkCreateBuffer;
     public static VkDestroyBuffer vkDestroyBuffer;
+    public static VkCreateImage vkCreateImage;
+    public static VkDestroyImage vkDestroyImage;
+    public static VkGetImageMemoryRequirements vkGetImageMemoryRequirements;
+    public static VkBindImageMemory vkBindImageMemory;
     public static VkAllocateMemory vkAllocateMemory;
     public static VkFreeMemory vkFreeMemory;
     public static VkBindBufferMemory vkBindBufferMemory;
@@ -208,6 +216,10 @@ internal static unsafe class Vk
         vkGetFenceStatus = LoadDev<VkGetFenceStatus>(p, "vkGetFenceStatus");
         vkCreateBuffer = LoadDev<VkCreateBuffer>(p, "vkCreateBuffer");
         vkDestroyBuffer = LoadDev<VkDestroyBuffer>(p, "vkDestroyBuffer");
+        vkCreateImage = LoadDev<VkCreateImage>(p, "vkCreateImage");
+        vkDestroyImage = LoadDev<VkDestroyImage>(p, "vkDestroyImage");
+        vkGetImageMemoryRequirements = LoadDev<VkGetImageMemoryRequirements>(p, "vkGetImageMemoryRequirements");
+        vkBindImageMemory = LoadDev<VkBindImageMemory>(p, "vkBindImageMemory");
         vkAllocateMemory = LoadDev<VkAllocateMemory>(p, "vkAllocateMemory");
         vkFreeMemory = LoadDev<VkFreeMemory>(p, "vkFreeMemory");
         vkBindBufferMemory = LoadDev<VkBindBufferMemory>(p, "vkBindBufferMemory");

src/Engine.Graphics.Vulkan/VulkanEnums.cs

@@ -61,6 +61,7 @@ public enum VkStructureType : int
     CommandBufferBeginInfo = 42,
     RenderPassBeginInfo = 43,
     ImageViewCreateInfo = 15,
+    ImageCreateInfo = 14,
     SemaphoreCreateInfo = 9,
     FenceCreateInfo = 8,
     SwapchainCreateInfoKHR = 1000001000,
@@ -207,6 +208,31 @@ public enum VkFrontFace : int
     Clockwise = 1,
 }
 
+public enum VkCompareOp : int
+{
+    Never = 0,
+    Less = 1,
+    Equal = 2,
+    LessOrEqual = 3,
+    Greater = 4,
+    NotEqual = 5,
+    GreaterOrEqual = 6,
+    Always = 7,
+}
+
+public enum VkImageType : int
+{
+    Type1D = 0,
+    Type2D = 1,
+    Type3D = 2,
+}
+
+public enum VkImageTiling : int
+{
+    Optimal = 0,
+    Linear = 1,
+}
+
 public enum VkBlendFactor : int
 {
     Zero = 0,
@@ -283,6 +309,8 @@ public enum VkPipelineStageFlags2 : ulong
 public enum VkAccessFlags2 : ulong
 {
     None = 0,
+    DepthStencilAttachmentWrite = 0x00000400,
+    DepthStencilAttachmentRead = 0x00000200,
     ColorAttachmentRead = 0x00000080,
     ColorAttachmentWrite = 0x00000100,
     TransferRead = 0x00000800,

src/Engine.Graphics.Vulkan/VulkanPipeline.cs

@@ -14,7 +14,7 @@ internal sealed unsafe class VulkanPipeline : IDisposable
     private readonly VkDevice _device;
     private bool _disposed;
 
-    public VulkanPipeline(VkDevice device, VkFormat colorFormat, byte[] vertSpv, byte[] fragSpv)
+    public VulkanPipeline(VkDevice device, VkFormat colorFormat, VkFormat depthFormat, byte[] vertSpv, byte[] fragSpv)
     {
         _device = device;
         VertModule = CreateShaderModule(vertSpv);
@@ -115,6 +115,16 @@ internal sealed unsafe class VulkanPipeline : IDisposable
                 sampleShadingEnable = VkBool32.False,
             };
 
+            var depthStencilState = new VkPipelineDepthStencilStateCreateInfo
+            {
+                sType = VkStructureType.PipelineDepthStencilStateCreateInfo,
+                depthTestEnable = VkBool32.True,
+                depthWriteEnable = VkBool32.True,
+                depthCompareOp = VkCompareOp.Less,
+                depthBoundsTestEnable = VkBool32.False,
+                stencilTestEnable = VkBool32.False,
+            };
+
             var blendAttachment = new VkPipelineColorBlendAttachmentState
             {
                 blendEnable = VkBool32.False,
@@ -144,7 +154,7 @@ internal sealed unsafe class VulkanPipeline : IDisposable
             {
                 stageFlags = VkShaderStageFlags.Vertex,
                 offset = 0,
-                size = 4,
+                size = 64,
             };
 
             var descLayout = DescriptorSetLayout;
@@ -169,6 +179,7 @@ internal sealed unsafe class VulkanPipeline : IDisposable
                 sType = VkStructureType.PipelineRenderingCreateInfo,
                 colorAttachmentCount = 1,
                 pColorAttachmentFormats = &colorFormat,
+                depthAttachmentFormat = depthFormat,
             };
 
             var pipelineInfo = new VkGraphicsPipelineCreateInfo
@@ -182,6 +193,7 @@ internal sealed unsafe class VulkanPipeline : IDisposable
                 pViewportState = &viewportState,
                 pRasterizationState = &rasterizationState,
                 pMultisampleState = &multisampleState,
+                pDepthStencilState = &depthStencilState,
                 pColorBlendState = &colorBlendState,
                 pDynamicState = &dynamicState,
                 layout = PipelineLayout,

src/Engine.Graphics.Vulkan/VulkanRenderContext.cs

@@ -23,7 +23,7 @@ internal sealed class VulkanRenderContext : IRenderContext
         };
 
         _swapchain = new VulkanSwapchain(_ctx.Device, _ctx.PhysicalDevice, _ctx.Surface,
-            surfaceFormat, window.Width, window.Height);
+            surfaceFormat, window.Width, window.Height, _ctx);
     }
 
     public IRenderer CreateRenderer()

src/Engine.Graphics.Vulkan/VulkanRenderer.cs

@@ -34,7 +34,7 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
         var vertSpv = LoadShader("Shaders/triangle.vert.spv");
         var fragSpv = LoadShader("Shaders/triangle.frag.spv");
 
-        _pipeline = new VulkanPipeline(ctx.Device, swapchain.Format, vertSpv, fragSpv);
+        _pipeline = new VulkanPipeline(ctx.Device, swapchain.Format, swapchain.DepthFormat, vertSpv, fragSpv);
 
         _frameResources = new VulkanFrameResources(ctx.Device, ctx.GraphicsQueueFamilyIndex,
             swapchain.ImageCount, ctx, _pipeline.DescriptorSetLayout);
@@ -109,11 +109,21 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
             0, 0,
             0x400, 0x100);
 
+        TransitionImageLayoutDepth(cmd, _swapchain.DepthImage,
+            VkImageLayout.Undefined, VkImageLayout.DepthStencilAttachmentOptimal,
+            0, 0,
+            0x100, 0x200);
+
         var clearValue = new VkClearValue
         {
             Color = new VkClearColorValue { Float0 = 0.02f, Float1 = 0.02f, Float2 = 0.02f, Float3 = 1.0f },
         };
 
+        var depthClearValue = new VkClearValue
+        {
+            DepthStencil = new VkClearDepthStencilValue { Depth = 1.0f, Stencil = 0 },
+        };
+
         var colorAttachment = new VkRenderingAttachmentInfo
         {
             sType = VkStructureType.RenderingAttachmentInfo,
@@ -124,6 +134,16 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
             clearValue = clearValue,
         };
 
+        var depthAttachment = new VkRenderingAttachmentInfo
+        {
+            sType = VkStructureType.RenderingAttachmentInfo,
+            imageView = _swapchain.DepthImageView,
+            imageLayout = VkImageLayout.DepthStencilAttachmentOptimal,
+            loadOp = VkAttachmentLoadOp.Clear,
+            storeOp = VkAttachmentStoreOp.Store,
+            clearValue = depthClearValue,
+        };
+
         var renderingInfo = new VkRenderingInfo
         {
             sType = VkStructureType.RenderingInfo,
@@ -135,6 +155,7 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
             layerCount = 1,
             colorAttachmentCount = 1,
             pColorAttachments = &colorAttachment,
+            pDepthAttachment = &depthAttachment,
         };
 
         Vk.vkCmdBeginRendering(cmd, &renderingInfo);
@@ -168,7 +189,8 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
         Vk.vkCmdBindIndexBuffer(cmd, _indexBuffer.Buffer, 0, 0);
 
         var angle = _totalTime;
-        Vk.vkCmdPushConstants(cmd, _pipeline.PipelineLayout, VkShaderStageFlags.Vertex, 0, 4, &angle);
+        var model = Matrix4x4.CreateRotationY(angle) * Matrix4x4.CreateRotationX(angle * 0.5f);
+        Vk.vkCmdPushConstants(cmd, _pipeline.PipelineLayout, VkShaderStageFlags.Vertex, 0, 64, &model);
 
         Vk.vkCmdDrawIndexed(cmd, _indexCount, 1, 0, 0, 0);
 
@@ -282,6 +304,39 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
         Vk.vkCmdPipelineBarrier2(cmd, &depInfo);
     }
 
+    private static void TransitionImageLayoutDepth(VkCommandBuffer cmd, VkImage image,
+        VkImageLayout oldLayout, VkImageLayout newLayout,
+        ulong srcStage, ulong srcAccess,
+        ulong dstStage, ulong dstAccess)
+    {
+        var barrier = new VkImageMemoryBarrier2
+        {
+            sType = VkStructureType.ImageMemoryBarrier2,
+            srcStageMask = srcStage,
+            srcAccessMask = srcAccess,
+            dstStageMask = dstStage,
+            dstAccessMask = dstAccess,
+            oldLayout = oldLayout,
+            newLayout = newLayout,
+            image = image,
+            subresourceRange = new VkImageSubresourceRange
+            {
+                AspectMask = VkImageAspectFlags.Depth,
+                LevelCount = 1,
+                LayerCount = 1,
+            },
+        };
+
+        var depInfo = new VkDependencyInfo
+        {
+            sType = VkStructureType.DependencyInfo,
+            imageMemoryBarrierCount = 1,
+            pImageMemoryBarriers = &barrier,
+        };
+
+        Vk.vkCmdPipelineBarrier2(cmd, &depInfo);
+    }
+
     private static byte[] LoadShader(string path)
     {
         if (!File.Exists(path))

src/Engine.Graphics.Vulkan/VulkanStructs.cs

@@ -671,7 +671,7 @@ public unsafe struct VkGraphicsPipelineCreateInfo
     public VkPipelineViewportStateCreateInfo* pViewportState;
     public VkPipelineRasterizationStateCreateInfo* pRasterizationState;
     public VkPipelineMultisampleStateCreateInfo* pMultisampleState;
-    public nint pDepthStencilState;
+    public VkPipelineDepthStencilStateCreateInfo* pDepthStencilState;
     public VkPipelineColorBlendStateCreateInfo* pColorBlendState;
     public VkPipelineDynamicStateCreateInfo* pDynamicState;
     public VkPipelineLayout layout;
@@ -792,7 +792,7 @@ public unsafe struct VkRenderingInfo
     public uint viewMask;
     public uint colorAttachmentCount;
     public VkRenderingAttachmentInfo* pColorAttachments;
-    public nint pDepthAttachment;
+    public VkRenderingAttachmentInfo* pDepthAttachment;
     public nint pStencilAttachment;
 }
 
@@ -908,6 +908,55 @@ public unsafe struct VkDebugUtilsMessengerCallbackDataEXT
     public nint pObjects;
 }
 
+[StructLayout(LayoutKind.Sequential)]
+public unsafe struct VkStencilOpState
+{
+    public int failOp;
+    public int passOp;
+    public int depthFailOp;
+    public int compareOp;
+    public uint compareMask;
+    public uint writeMask;
+    public uint reference;
+}
+
+[StructLayout(LayoutKind.Sequential)]
+public unsafe struct VkPipelineDepthStencilStateCreateInfo
+{
+    public VkStructureType sType;
+    public nint pNext;
+    public uint flags;
+    public VkBool32 depthTestEnable;
+    public VkBool32 depthWriteEnable;
+    public VkCompareOp depthCompareOp;
+    public VkBool32 depthBoundsTestEnable;
+    public VkBool32 stencilTestEnable;
+    public VkStencilOpState front;
+    public VkStencilOpState back;
+    public float minDepthBounds;
+    public float maxDepthBounds;
+}
+
+[StructLayout(LayoutKind.Sequential)]
+public unsafe struct VkImageCreateInfo
+{
+    public VkStructureType sType;
+    public nint pNext;
+    public uint flags;
+    public VkImageType imageType;
+    public VkFormat format;
+    public VkExtent3D extent;
+    public uint mipLevels;
+    public uint arrayLayers;
+    public VkSampleCountFlags samples;
+    public VkImageTiling tiling;
+    public VkImageUsageFlags usage;
+    public VkSharingMode sharingMode;
+    public uint queueFamilyIndexCount;
+    public uint* pQueueFamilyIndices;
+    public VkImageLayout initialLayout;
+}
+
 [StructLayout(LayoutKind.Sequential)]
 public unsafe struct VkPushConstantRange
 {

src/Engine.Graphics.Vulkan/VulkanSwapchain.cs

@@ -11,19 +11,26 @@ internal sealed unsafe class VulkanSwapchain : IDisposable
     public VkExtent2D Extent;
     public uint ImageCount;
 
+    public VkImage DepthImage;
+    public VkDeviceMemory DepthImageMemory;
+    public VkImageView DepthImageView;
+    public VkFormat DepthFormat = VkFormat.D32Sfloat;
+
     private readonly VkDevice _device;
     private readonly VkPhysicalDevice _physicalDevice;
     private readonly VkSurfaceKHR _surface;
     private readonly VkSurfaceFormatKHR _surfaceFormat;
+    private readonly VulkanContext _ctx;
     private bool _disposed;
 
     public VulkanSwapchain(VkDevice device, VkPhysicalDevice physicalDevice, VkSurfaceKHR surface,
-        VkSurfaceFormatKHR surfaceFormat, int width, int height)
+        VkSurfaceFormatKHR surfaceFormat, int width, int height, VulkanContext ctx)
     {
         _device = device;
         _physicalDevice = physicalDevice;
         _surface = surface;
         _surfaceFormat = surfaceFormat;
+        _ctx = ctx;
         Create(width, height);
     }
 
@@ -132,6 +139,81 @@ internal sealed unsafe class VulkanSwapchain : IDisposable
         }
 
         Console.WriteLine($"[Vulkan] Swapchain: {actualCount} images, {Extent.Width}x{Extent.Height}, format={Format}");
+
+        CreateDepthResources();
+    }
+
+    private void CreateDepthResources()
+    {
+        var imageInfo = new VkImageCreateInfo
+        {
+            sType = VkStructureType.ImageCreateInfo,
+            imageType = VkImageType.Type2D,
+            format = DepthFormat,
+            extent = new VkExtent3D { Width = Extent.Width, Height = Extent.Height, Depth = 1 },
+            mipLevels = 1,
+            arrayLayers = 1,
+            samples = VkSampleCountFlags.Count1,
+            tiling = VkImageTiling.Optimal,
+            usage = VkImageUsageFlags.DepthStencilAttachment,
+            sharingMode = VkSharingMode.Exclusive,
+            initialLayout = VkImageLayout.Undefined,
+        };
+
+        var depthImg = VkImage.Null;
+        var result = Vk.vkCreateImage(_device, &imageInfo, 0, &depthImg);
+        if (result != VkResult.Success)
+            throw new InvalidOperationException($"vkCreateImage (depth) failed: {result}");
+        DepthImage = depthImg;
+
+        var reqs = new VkMemoryRequirements();
+        Vk.vkGetImageMemoryRequirements(_device, DepthImage, &reqs);
+
+        var memTypeIndex = _ctx.FindMemoryType(reqs.memoryTypeBits, VkMemoryPropertyFlags.DeviceLocal);
+
+        var allocInfo = new VkMemoryAllocateInfo
+        {
+            sType = VkStructureType.MemoryAllocateInfo,
+            allocationSize = reqs.size,
+            memoryTypeIndex = memTypeIndex,
+        };
+
+        var depthMem = VkDeviceMemory.Null;
+        result = Vk.vkAllocateMemory(_device, &allocInfo, 0, &depthMem);
+        if (result != VkResult.Success)
+            throw new InvalidOperationException($"vkAllocateMemory (depth) failed: {result}");
+        DepthImageMemory = depthMem;
+
+        Vk.vkBindImageMemory(_device, DepthImage, DepthImageMemory, 0);
+
+        var viewInfo = new VkImageViewCreateInfo
+        {
+            sType = VkStructureType.ImageViewCreateInfo,
+            image = DepthImage,
+            viewType = VkImageViewType.Type2D,
+            format = DepthFormat,
+            components = new VkComponentMapping
+            {
+                R = VkComponentSwizzle.Identity,
+                G = VkComponentSwizzle.Identity,
+                B = VkComponentSwizzle.Identity,
+                A = VkComponentSwizzle.Identity,
+            },
+            subresourceRange = new VkImageSubresourceRange
+            {
+                AspectMask = VkImageAspectFlags.Depth,
+                BaseMipLevel = 0,
+                LevelCount = 1,
+                BaseArrayLayer = 0,
+                LayerCount = 1,
+            },
+        };
+
+        var depthView = VkImageView.Null;
+        result = Vk.vkCreateImageView(_device, &viewInfo, 0, &depthView);
+        if (result != VkResult.Success)
+            throw new InvalidOperationException($"vkCreateImageView (depth) failed: {result}");
+        DepthImageView = depthView;
     }
 
     public void Recreate(int width, int height)
@@ -143,6 +225,22 @@ internal sealed unsafe class VulkanSwapchain : IDisposable
 
     private void Cleanup()
     {
+        if (DepthImageView.Handle != 0)
+        {
+            Vk.vkDestroyImageView(_device, DepthImageView, 0);
+            DepthImageView = VkImageView.Null;
+        }
+        if (DepthImage.Handle != 0)
+        {
+            Vk.vkDestroyImage(_device, DepthImage, 0);
+            DepthImage = VkImage.Null;
+        }
+        if (DepthImageMemory.Handle != 0)
+        {
+            Vk.vkFreeMemory(_device, DepthImageMemory, 0);
+            DepthImageMemory = VkDeviceMemory.Null;
+        }
+
         for (int i = 0; i < ImageViews.Length; i++)
         {
             if (ImageViews[i].Handle != 0)