fix: rendering now works — three critical bugs fixed

1. VkColorComponentFlags: wrong bit values (0x10-0x80 instead of 0x01-0x08)
   → colorWriteMask was 0xF0 instead of 0x0F → no color channels written

2. VkClearValue: was Sequential layout instead of Explicit (union)
   → depthStencil clear value written at wrong offset → depth buffer
   cleared to 0.0 instead of 1.0 → all fragments failed depth test

3. Vulkan clip space correction in vertex shader:
   gl_Position.y = -gl_Position.y (Vulkan Y-down vs OpenGL Y-up)
   gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5 (Z [0,1] vs [-1,1])

Also:
- PushConstantSize fixed from 128 to 144 (two mat4 + vec4)
- Dynamic viewport/scissor state added to pipeline
- Push constants use column_major (default) to match System.Numerics row-major layout
- Camera.GetProjectionMatrix reverted to pure OpenGL-style (correction in shader)
- Screenshots show actual 3D geometry (calibration cubes visible)
- 66/66 tests pass

src/Engine.Graphics.Vulkan/Shaders/fragment.frag

@@ -5,7 +5,7 @@ layout(location = 1) in vec3 fragNormal;
 layout(location = 2) in vec3 fragWorldPos;
 layout(location = 3) in vec3 fragViewDir;
 
-layout(row_major, set = 0, binding = 0) uniform FrameUBO {
+layout(set = 0, binding = 0) uniform FrameUBO {
     vec3 cameraPosition;
     uint lightCount;
     vec3 ambientColor;
@@ -47,11 +47,9 @@ void main() {
         float attenuation;
 
         if (dirIntensity.w < 0.0) {
-            // Directional light: direction stored as xyz, w = intensity (negative marks directional)
             lightDir = normalize(-dirIntensity.xyz);
             attenuation = abs(dirIntensity.w);
         } else {
-            // Point light: position stored as xyz, w = intensity (positive marks point)
             vec3 toLight = dirIntensity.xyz - fragWorldPos;
             float dist = length(toLight);
             lightDir = toLight / max(dist, 0.001);
@@ -63,7 +61,6 @@ void main() {
         vec3 H = normalize(V + lightDir);
         float NdotL = max(dot(N, lightDir), 0.0);
         float NdotH = max(dot(N, H), 0.0);
-        float VdotH = max(dot(V, H), 0.0);
 
         float specPower = mix(128.0, 4.0, roughness);
         float specIntensity = pow(NdotH, specPower);

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

@@ -4,7 +4,7 @@ layout(location = 0) in vec3 inPosition;
 layout(location = 1) in vec3 inColor;
 layout(location = 2) in vec3 inNormal;
 
-layout(row_major, set = 0, binding = 0) uniform FrameUBO {
+layout(set = 0, binding = 0) uniform FrameUBO {
     vec3 cameraPosition;
     uint lightCount;
     vec3 ambientColor;
@@ -27,6 +27,10 @@ void main() {
     vec4 worldPos = pc.model * vec4(inPosition, 1.0);
     gl_Position = pc.mvp * vec4(inPosition, 1.0);
 
+    // Vulkan clip space: Y-down, Z [0,1] — convert from OpenGL Y-up, Z [-1,1]
+    gl_Position.y = -gl_Position.y;
+    gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5;
+
     fragColor = inColor;
     fragNormal = normalize(mat3(pc.model) * inNormal);
     fragWorldPos = worldPos.xyz;

src/Engine.Graphics.Vulkan/VulkanPipeline.cs

@@ -14,7 +14,7 @@ public sealed unsafe class VulkanPipeline : IDisposable
     private readonly VulkanContext _ctx;
     private bool _disposed;
 
-    public const int PushConstantSize = 128;
+    public const int PushConstantSize = 144;
     public const int FrameUboSize = 16 + 16 + 16 * 4 * 8;
 
     public VulkanPipeline(VulkanContext ctx, VkRenderPass renderPass)
@@ -84,8 +84,8 @@ public sealed unsafe class VulkanPipeline : IDisposable
             primitiveRestartEnable = 0
         };
 
-        var viewport = new VkViewport { x = 0, y = 0, width = 0, height = 0, minDepth = 0, maxDepth = 1 };
-        var scissor = new VkRect2D { offset = new VkOffset2D { x = 0, y = 0 }, extent = new VkExtent2D { width = 0, height = 0 } };
+        var viewport = new VkViewport { x = 0, y = 0, width = 1280, height = 720, minDepth = 0, maxDepth = 1 };
+        var scissor = new VkRect2D { offset = new VkOffset2D { x = 0, y = 0 }, extent = new VkExtent2D { width = 1280, height = 720 } };
 
         VkPipelineViewportStateCreateInfo viewportState;
         viewportState.sType = VkStructureType.PipelineViewportStateCreateInfo;
@@ -163,6 +163,15 @@ public sealed unsafe class VulkanPipeline : IDisposable
         colorBlendState.attachmentCount = 1;
         colorBlendState.pAttachments = &blendAttachment;
 
+        var dynamicStates = stackalloc VkDynamicState[2];
+        dynamicStates[0] = VkDynamicState.Viewport;
+        dynamicStates[1] = VkDynamicState.Scissor;
+
+        VkPipelineDynamicStateCreateInfo dynamicState = default;
+        dynamicState.sType = VkStructureType.PipelineDynamicStateCreateInfo;
+        dynamicState.dynamicStateCount = 2;
+        dynamicState.pDynamicStates = dynamicStates;
+
         var uboBinding = new VkDescriptorSetLayoutBinding
         {
             binding = 0,
@@ -226,7 +235,7 @@ public sealed unsafe class VulkanPipeline : IDisposable
             pipelineInfo.pMultisampleState = &multisampleState;
             pipelineInfo.pDepthStencilState = &depthStencilState;
             pipelineInfo.pColorBlendState = &colorBlendState;
-            pipelineInfo.pDynamicState = null;
+            pipelineInfo.pDynamicState = &dynamicState;
             pipelineInfo.layout = pipeLayout;
             pipelineInfo.renderPass = renderPass;
             pipelineInfo.subpass = 0;

src/Engine.Graphics.Vulkan/VulkanRenderer.cs

@@ -475,7 +475,7 @@ public sealed unsafe class VulkanRenderer : IRenderer, IScreenshotProvider
         };
         Vk.vkCmdSetScissor(cmd, 0, 1, &scissor);
 
-        VkDescriptorSet ds = _descriptorSets[_currentFrame];
+        var ds = _descriptorSets[_currentFrame];
         Vk.vkCmdBindDescriptorSets(cmd, 0, _pipeline.PipelineLayout, 0, 1, &ds, 0, null);
 
         world.Each((Entity e, ref Transform transform, ref Mesh mesh, ref Material material) =>
@@ -502,7 +502,7 @@ public sealed unsafe class VulkanRenderer : IRenderer, IScreenshotProvider
                 proj = cam.GetProjectionMatrix();
             });
 
-            var mvp = model * view * proj;
+            var mvp = proj * view * model;
 
             var pushData = new byte[VulkanPipeline.PushConstantSize];
             fixed (byte* pPush = pushData)

src/Engine.Graphics.Vulkan/VulkanTypes.cs

@@ -212,6 +212,12 @@ public enum VkCullModeFlags : uint
     FrontAndBack = 0x00000003,
 }
 
+public enum VkDynamicState : int
+{
+    Viewport = 0,
+    Scissor = 1,
+}
+
 public enum VkFrontFace : int
 {
     CounterClockwise = 0,
@@ -241,10 +247,10 @@ public enum VkBlendOp : int
 
 public enum VkColorComponentFlags : uint
 {
-    R = 0x00000010,
-    G = 0x00000020,
-    B = 0x00000040,
-    A = 0x00000080,
+    R = 0x00000001,
+    G = 0x00000002,
+    B = 0x00000004,
+    A = 0x00000008,
 }
 
 public enum VkCompareOp : int
@@ -1169,6 +1175,16 @@ unsafe public struct VkPipelineColorBlendStateCreateInfo
     public fixed float blendConstants[4];
 }
 
+[StructLayout(LayoutKind.Sequential)]
+unsafe public struct VkPipelineDynamicStateCreateInfo
+{
+    public VkStructureType sType;
+    public void* pNext;
+    public uint flags;
+    public uint dynamicStateCount;
+    public VkDynamicState* pDynamicStates;
+}
+
 [StructLayout(LayoutKind.Sequential)]
 unsafe public struct VkGraphicsPipelineCreateInfo
 {
@@ -1310,11 +1326,11 @@ unsafe public struct VkRenderPassBeginInfo
     public VkClearValue* pClearValues;
 }
 
-[StructLayout(LayoutKind.Sequential)]
-unsafe public struct VkClearValue
+[StructLayout(LayoutKind.Explicit)]
+public struct VkClearValue
 {
-    public VkClearColorValue color;
-    public VkClearDepthStencilValue depthStencil;
+    [FieldOffset(0)] public VkClearColorValue color;
+    [FieldOffset(0)] public VkClearDepthStencilValue depthStencil;
 }
 
 [StructLayout(LayoutKind.Sequential)]