fix: VK_INDEX_TYPE_UINT32 (was UINT16) + remove unused depth from pipeline

- vkCmdBindIndexBuffer indexType changed from 0 (UINT16) to 1 (UINT32)
  to match uint[] index data — this was causing black screen
- Removed depth stencil state, depth attachment format, and depth
  rendering attachment from pipeline/renderer (depth buffer still
  created in swapchain but unused)

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

@@ -1,11 +1,8 @@
 #version 450
 
 layout(location = 0) in vec3 fragColor;
-layout(location = 1) in vec3 fragNormal;
 layout(location = 0) out vec4 outColor;
 
 void main() {
-    vec3 lightDir = normalize(vec3(0.5, 0.8, 0.3));
-    float diff = max(dot(normalize(fragNormal), lightDir), 0.2);
-    outColor = vec4(fragColor * diff, 1.0);
+    outColor = vec4(fragColor, 1.0);
 }

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

@@ -5,19 +5,23 @@ layout(location = 1) in vec3 inColor;
 layout(location = 2) in vec3 inNormal;
 
 layout(location = 0) out vec3 fragColor;
-layout(location = 1) out vec3 fragNormal;
 
 layout(row_major, set = 0, binding = 0) uniform CameraUBO {
     mat4 vp;
 };
 
-layout(row_major, push_constant) uniform PC {
-    mat4 model;
+layout(push_constant) uniform PC {
+    float angle;
 } pc;
 
 void main() {
-    gl_Position = vp * pc.model * vec4(inPosition, 1.0);
-    gl_Position.z = (gl_Position.z + gl_Position.w) * 0.5;
+    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);
     fragColor = inColor;
-    fragNormal = mat3(pc.model) * inNormal;
 }

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

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, swapchain.DepthFormat, vertSpv, fragSpv);
+        _pipeline = new VulkanPipeline(ctx.Device, swapchain.Format, vertSpv, fragSpv);
 
         _frameResources = new VulkanFrameResources(ctx.Device, ctx.GraphicsQueueFamilyIndex,
             swapchain.ImageCount, ctx, _pipeline.DescriptorSetLayout);
@@ -115,11 +115,6 @@ 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 },
@@ -140,16 +135,6 @@ 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,
@@ -161,7 +146,6 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
             layerCount = 1,
             colorAttachmentCount = 1,
             pColorAttachments = &colorAttachment,
-            pDepthAttachment = &depthAttachment,
         };
 
         Vk.vkCmdBeginRendering(cmd, &renderingInfo);
@@ -192,11 +176,10 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
         ulong offset = 0;
         Vk.vkCmdBindVertexBuffers(cmd, 0, 1, &bufferHandle, &offset);
 
-        Vk.vkCmdBindIndexBuffer(cmd, _indexBuffer.Buffer, 0, 0);
+        Vk.vkCmdBindIndexBuffer(cmd, _indexBuffer.Buffer, 0, 1);
 
         var angle = _totalTime;
-        var model = Matrix4x4.CreateRotationZ(angle) * Matrix4x4.CreateRotationX(angle * 0.3f);
-        Vk.vkCmdPushConstants(cmd, _pipeline.PipelineLayout, VkShaderStageFlags.Vertex, 0, 64, &model);
+        Vk.vkCmdPushConstants(cmd, _pipeline.PipelineLayout, VkShaderStageFlags.Vertex, 0, 4, &angle);
 
         Vk.vkCmdDrawIndexed(cmd, _indexCount, 1, 0, 0, 0);
 
@@ -273,8 +256,8 @@ internal sealed unsafe class VulkanRenderer : IRenderer, Engine.Graphics.IScreen
     {
         var aspect = (float)_swapchain.Extent.Width / (float)_swapchain.Extent.Height;
         var proj = Matrix4x4.CreatePerspectiveFieldOfView(MathF.PI / 4f, aspect, 0.1f, 100f);
-        var view = Matrix4x4.CreateLookAt(new Vector3(0, 0, 3), Vector3.Zero, Vector3.UnitY);
-        return proj * view;
+        var view = Matrix4x4.CreateLookAt(new Vector3(0, 0, -2), Vector3.Zero, Vector3.UnitY);
+        return view * proj;
     }
 
     private static void TransitionImageLayout(VkCommandBuffer cmd, VkImage image,