WIP: Subpasses

build.zig

@@ -28,11 +28,14 @@ pub fn build(b: *std.Build) void {
 
     const shader_comp = vkgen.ShaderCompileStep.create(
         b,
-        &[_][]const u8{ "glslc", "--target-env=vulkan1.3" },
+        .{ .real_path = "glslc" },
+        &[_][]const u8{"--target-env=vulkan1.3"},
         "-o",
     );
     shader_comp.add("shader_frag", "src/shaders/shader.frag", .{});
     shader_comp.add("shader_vert", "src/shaders/shader.vert", .{});
+    shader_comp.add("shader_frag", "src/shaders/second.frag", .{});
+    shader_comp.add("shader_vert", "src/shaders/second.vert", .{});
     exe.root_module.addImport("shaders", shader_comp.getModule());
 
     // SDL2

build.zig.zon

@@ -7,8 +7,8 @@
         .zmath = .{ .path = "libs/zmath" },
         .zstbi = .{ .path = "libs/zstbi" },
         .vulkan_zig = .{
-            .url = "https://github.com/Snektron/vulkan-zig/archive/9f6e6177b1fdb3ed22231d9216a24480e84cfa5e.tar.gz",
+            .url = "https://github.com/Snektron/vulkan-zig/archive/18f38ef2b7ae394734bd8b28d43f120f2b9567c1.tar.gz",
-            .hash = "1220f2961df224f7d35dee774b26194b8b937cc252fa8e4023407776c58521d53e38",
+            .hash = "1220530d62adb3f7ab87bacde31c302955a5803db52e302a0c7f8e107ca03f7aeca5",
         },
         .obj = .{
             .url = "https://github.com/chip2n/zig-obj/archive/58f524ed6834790b29ac1e97b2f9e6b7de7b5346.tar.gz",

src/shaders/second.frag

@@ -0,0 +1,13 @@
+#version 450
+
+// Colour output from subpass 1
+layout(input_attachment_index = 0, binding = 0) uniform subpassInput inputColour;
+
+// Depth output from subpass 1
+layout(input_attachment_index = 1, binding = 1) uniform subpassInput inputDepth;
+
+layout(location = 0) out vec4 colour;
+
+void main() {
+    colour = subpassLoad(inputColour).rgba;
+}

src/shaders/second.vert

@@ -0,0 +1,12 @@
+#version 450
+
+// Array for triangle that fills screen
+vec2 positions[3] = vec2[](
+    vec2(3.0, -1.0),
+    vec2(-1.0, -1.0),
+    vec2(-1.0, 3.0),
+);
+
+void main() {
+    gl_Position = vec4(positions[gl_VertexIndex], 0.0, 1.0);
+}

src/vulkan_renderer.zig

@@ -82,19 +82,26 @@ pub const VulkanRenderer = struct {
     swapchain_framebuffers: []vk.Framebuffer,
     command_buffers: []CommandBuffer,
 
-    depth_buffer_image: vk.Image,
+    depth_buffer_image: []vk.Image,
-    depth_buffer_image_memory: vk.DeviceMemory,
+    depth_buffer_image_memory: []vk.DeviceMemory,
-    depth_buffer_image_view: vk.ImageView,
+    depth_buffer_image_view: []vk.ImageView,
+
+    colour_buffer_image: []vk.Image,
+    colour_buffer_image_memory: []vk.DeviceMemory,
+    colour_buffer_image_view: []vk.ImageView,
 
     // Descriptors
     descriptor_set_layout: vk.DescriptorSetLayout,
     sampler_set_layout: vk.DescriptorSetLayout,
+    input_set_layout: vk.DescriptorSetLayout,
     push_constant_range: vk.PushConstantRange,
 
     descriptor_pool: vk.DescriptorPool,
     sampler_descriptor_pool: vk.DescriptorPool,
+    input_descriptor_pool: vk.DescriptorPool,
     descriptor_sets: []vk.DescriptorSet,
     sampler_descriptor_sets: std.ArrayList(vk.DescriptorSet),
+    input_descriptor_sets: std.ArrayList(vk.DescriptorSet),
 
     vp_uniform_buffer: []vk.Buffer,
     vp_uniform_buffer_memory: []vk.DeviceMemory,
@@ -109,6 +116,10 @@ pub const VulkanRenderer = struct {
     // Pipeline
     graphics_pipeline: vk.Pipeline,
     pipeline_layout: vk.PipelineLayout,
+
+    second_pipeline: vk.Pipeline,
+    second_pipeline_layout: vk.PipelineLayout,
+
     render_pass: vk.RenderPass,
 
     // Pools
@@ -146,6 +157,7 @@ pub const VulkanRenderer = struct {
         try self.getPhysicalDevice();
         try self.createLogicalDevice();
         try self.createSwapchain();
+        try self.createColourBufferImage();
         try self.createDepthBufferImage();
         try self.createRenderPass();
         try self.createDescriptorSetLayout();
@@ -154,12 +166,15 @@ pub const VulkanRenderer = struct {
         try self.createFramebuffers();
         try self.createCommandPool();
 
+        self.sampler_descriptor_sets = try std.ArrayList(vk.DescriptorSet).initCapacity(self.allocator, self.swapchain_images.len);
+        self.input_descriptor_sets = try std.ArrayList(vk.DescriptorSet).initCapacity(self.allocator, self.swapchain_images.len);
+
         try self.createCommandBuffers();
         try self.createTextureSampler();
         try self.createUniformBuffers();
         try self.createDescriptorPool();
         try self.createDescriptorSets();
-
+        try self.createInputDescriptorSets();
         try self.createSynchronisation();
 
         self.image_files = std.ArrayList(img.Image).init(self.allocator);
@@ -167,7 +182,6 @@ pub const VulkanRenderer = struct {
         self.texture_image_memory = std.ArrayList(vk.DeviceMemory).init(self.allocator);
         self.texture_image_views = std.ArrayList(vk.ImageView).init(self.allocator);
         self.model_list = std.ArrayList(MeshModel).init(allocator);
-        self.sampler_descriptor_sets = std.ArrayList(vk.DescriptorSet).init(self.allocator);
 
         const aspect: f32 = @as(f32, @floatFromInt(self.extent.width)) / @as(f32, @floatFromInt(self.extent.height));
         self.ubo_view_projection.projection = zm.perspectiveFovRh(
@@ -289,14 +303,32 @@ pub const VulkanRenderer = struct {
         self.texture_image_memory.deinit();
         self.texture_image_views.deinit();
 
-        self.device.destroyImageView(self.depth_buffer_image_view, null);
+        for (0..self.depth_buffer_image.len) |i| {
-        self.device.destroyImage(self.depth_buffer_image, null);
+            self.device.destroyImageView(self.depth_buffer_image_view[i], null);
-        self.device.freeMemory(self.depth_buffer_image_memory, null);
+            self.device.destroyImage(self.depth_buffer_image[i], null);
+            self.device.freeMemory(self.depth_buffer_image_memory[i], null);
+        }
 
+        self.allocator.free(self.depth_buffer_image);
+        self.allocator.free(self.depth_buffer_image_memory);
+        self.allocator.free(self.depth_buffer_image_view);
+
+        for (0..self.colour_buffer_image.len) |i| {
+            self.device.destroyImageView(self.colour_buffer_image_view[i], null);
+            self.device.destroyImage(self.colour_buffer_image[i], null);
+            self.device.freeMemory(self.colour_buffer_image_memory[i], null);
+        }
+
+        self.allocator.free(self.colour_buffer_image);
+        self.allocator.free(self.colour_buffer_image_memory);
+        self.allocator.free(self.colour_buffer_image_view);
+
+        self.device.destroyDescriptorPool(self.input_descriptor_pool, null);
         self.device.destroyDescriptorPool(self.descriptor_pool, null);
         self.device.destroyDescriptorSetLayout(self.descriptor_set_layout, null);
         self.device.destroyDescriptorPool(self.sampler_descriptor_pool, null);
         self.device.destroyDescriptorSetLayout(self.sampler_set_layout, null);
+        self.device.destroyDescriptorSetLayout(self.input_set_layout, null);
         self.sampler_descriptor_sets.deinit();
 
         for (0..self.swapchain_images.len) |i| {
@@ -523,8 +555,65 @@ pub const VulkanRenderer = struct {
 
     fn createRenderPass(self: *Self) !void {
         // -- Attachments --
-        // Colour attachment of the render pass
+
+        const subpasses: [2]vk.SubpassDescription = undefined;
+
+        // Subpass 1 attachments and references (input attachments)
+
+        // Colour attachment (input)
+        const colour_format = chooseSupportedFormat(
+            self.physical_device,
+            self.instance,
+            &[_]vk.Format{.r8g8b8a8_srgb},
+            .optimal,
+            .{ .color_attachment_bit = true },
+        );
         const colour_attachment: vk.AttachmentDescription = .{
+            .format = colour_format,
+            .samples = .{ .@"1_bit" = true },
+            .load_op = .clear,
+            .store_op = .dont_care,
+            .stencil_load_op = .dont_care,
+            .stencil_store_op = .dont_care,
+            .initial_layout = .undefined,
+            .final_layout = .color_attachment_optimal,
+        };
+
+        // Depth attachment (input)
+        const depth_attachment: vk.AttachmentDescription = .{
+            .format = self.depth_format,
+            .samples = .{ .@"1_bit" = true },
+            .load_op = .clear,
+            .store_op = .dont_care,
+            .stencil_load_op = .dont_care,
+            .stencil_store_op = .dont_care,
+            .initial_layout = .undefined,
+            .final_layout = .depth_stencil_attachment_optimal,
+        };
+
+        // Colour attachment (input) reference
+        const colour_attachment_reference: vk.AttachmentReference = .{
+            .attachment = 1,
+            .layout = .color_attachment_optimal,
+        };
+
+        // Depth attachment (input) reference
+        const depth_attachment_reference: vk.AttachmentReference = .{
+            .attachment = 2,
+            .layout = .depth_stencil_attachment_optimal,
+        };
+
+        subpasses[0] = .{
+            .pipeline_bind_point = .graphics, // Pipeline type subpass is to be bound to
+            .color_attachment_count = 1,
+            .p_color_attachments = @ptrCast(&colour_attachment_reference),
+            .p_depth_stencil_attachment = &depth_attachment_reference,
+        };
+
+        // Subpass 2 attachments and references
+
+        // Colour attachment of the render pass
+        const swapchain_colour_attachment: vk.AttachmentDescription = .{
             .format = self.swapchain_image_format, // Format to use for attachment
             .samples = .{ .@"1_bit" = true }, // Number of samples to write for multisampling
             .load_op = .clear, // Describes what to do with attachment before rendering
@@ -537,40 +626,36 @@ pub const VulkanRenderer = struct {
             .final_layout = vk.ImageLayout.present_src_khr, // Image data layout after render pass (to change to)
         };
 
-        // Depth attachment of render pass
-        const depth_attachment: vk.AttachmentDescription = .{
-            .format = self.depth_format,
-            .samples = .{ .@"1_bit" = true },
-            .load_op = .clear,
-            .store_op = .dont_care,
-            .stencil_load_op = .dont_care,
-            .stencil_store_op = .dont_care,
-            .initial_layout = .undefined,
-            .final_layout = .depth_stencil_attachment_optimal,
-        };
-
-        // -- References --
         // Attachment reference uses an attachment index that refers to index in the attachment list passed to render pass create info
-        const colour_attachment_reference: vk.AttachmentReference = .{
+        const swapchain_colour_attachment_reference: vk.AttachmentReference = .{
             .attachment = 0,
             .layout = vk.ImageLayout.color_attachment_optimal,
         };
 
-        const depth_attachment_reference: vk.AttachmentReference = .{
+        // References to attachments that subpass will take input from
-            .attachment = 1,
+        const input_references = [_]vk.AttachmentReference{
-            .layout = vk.ImageLayout.depth_stencil_attachment_optimal,
+            .{
+                .attachment = 1, // Colour attachment
+                .layout = .shader_read_only_optimal,
+            },
+            .{
+                .attachment = 2, // Depth attachment
+                .layout = .shader_read_only_optimal,
+            },
         };
 
-        // Information about a particular subpass the render pass is using
+        subpasses[1] = .{
-        const subpass: vk.SubpassDescription = .{
+            .pipeline_bind_point = .graphics,
-            .pipeline_bind_point = .graphics, // Pipeline type subpass is to be bound to
             .color_attachment_count = 1,
-            .p_color_attachments = @ptrCast(&colour_attachment_reference),
+            .p_color_attachments = @ptrCast(&swapchain_colour_attachment_reference),
-            .p_depth_stencil_attachment = &depth_attachment_reference,
+            .input_attachment_count = @intCast(input_references.len),
+            .p_input_attachments = &input_references,
         };
 
+        // -- Subpass dependencies
+
         // Need to determine when layout transitions occur using subpass dependencies
-        const subpass_dependencies = [2]vk.SubpassDependency{
+        const subpass_dependencies = [_]vk.SubpassDependency{
             // Conversion from VK_IMAGE_LAYOUT_UNDEFINED to VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL
             vk.SubpassDependency{
                 // Transition must happen after...
@@ -582,6 +667,15 @@ pub const VulkanRenderer = struct {
                 .dst_stage_mask = .{ .color_attachment_output_bit = true },
                 .dst_access_mask = .{ .color_attachment_read_bit = true, .color_attachment_write_bit = true },
             },
+            // Subpass 1 layout (colour/depth) to subpass 2 layout (shader read)
+            .{
+                .src_subpass = 0,
+                .src_stage_mask = .{ .color_attachment_output_bit = true },
+                .src_access_mask = .{ .color_attachment_write_bit = true },
+                .dst_subpass = 1,
+                .dst_stage_mask = .{ .fragment_shader_bit = true },
+                .dst_access_mask = .{ .shader_read_bit = true },
+            },
             // Conversion from VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL to VK_IMAGE_LAYOUT_PRESENT_SRC_KHR
             vk.SubpassDependency{
                 // Transition must happen after...
@@ -596,13 +690,13 @@ pub const VulkanRenderer = struct {
         };
 
         // Order matters
-        const render_pass_attachments = [_]vk.AttachmentDescription{ colour_attachment, depth_attachment };
+        const render_pass_attachments = [_]vk.AttachmentDescription{ swapchain_colour_attachment, colour_attachment, depth_attachment };
 
         const render_pass_create_info: vk.RenderPassCreateInfo = .{
             .attachment_count = @intCast(render_pass_attachments.len),
             .p_attachments = &render_pass_attachments,
-            .subpass_count = 1,
+            .subpass_count = @intCast(subpasses.len),
-            .p_subpasses = @ptrCast(&subpass),
+            .p_subpasses = &subpasses,
             .dependency_count = @intCast(subpass_dependencies.len),
             .p_dependencies = &subpass_dependencies,
         };
@@ -651,6 +745,34 @@ pub const VulkanRenderer = struct {
         };
 
         self.sampler_set_layout = try self.device.createDescriptorSetLayout(&texture_layout_info, null);
+
+        // -- Create input attachment image descriptor set layout
+        // Colour input binding
+        const colour_input_layout_binding: vk.DescriptorSetLayoutBinding = .{
+            .binding = 0,
+            .descriptor_type = .input_attachment,
+            .descriptor_count = 1,
+            .stage_flags = .{ .fragment_bit = true },
+        };
+
+        // Depth input binding
+        const depth_input_layout_binding: vk.DescriptorSetLayoutBinding = .{
+            .binding = 1,
+            .descriptor_type = .input_attachment,
+            .descriptor_count = 1,
+            .stage_flags = .{ .fragment_bit = true },
+        };
+
+        // Array of input attachment bindings
+        const input_bindings = [_]vk.DescriptorSetLayoutBinding{ colour_input_layout_binding, depth_input_layout_binding };
+
+        // Create a descriptor set layout for input attachments
+        const input_layout_create_info: vk.DescriptorSetLayoutCreateInfo = .{
+            .binding_count = @intCast(input_bindings.len),
+            .p_bindings = &input_bindings,
+        };
+
+        self.input_set_layout = try self.device.createDescriptorSetLayout(&input_layout_create_info, null);
     }
 
     fn createPushConstantRange(self: *Self) !void {
@@ -662,7 +784,45 @@ pub const VulkanRenderer = struct {
         };
     }
 
+    fn createColourBufferImage(self: *Self) !void {
+        self.colour_buffer_image = try self.allocator.alloc(vk.Image, self.swapchain_images.len);
+        self.colour_buffer_image_memory = try self.allocator.alloc(vk.DeviceMemory, self.swapchain_images.len);
+        self.colour_buffer_image_view = try self.allocator.alloc(vk.ImageView, self.swapchain_images.len);
+
+        // Get supported format for colour attachment
+        const colour_format = chooseSupportedFormat(
+            self.physical_device,
+            self.instance,
+            &[_]vk.Format{.r8g8b8a8_srgb},
+            .optimal,
+            .{ .color_attachment_bit = true },
+        ) orelse return error.FormatNotSupported;
+
+        // Create colour buffers
+        for (0..self.colour_buffer_image.len) |i| {
+            self.colour_buffer_image[i] = try self.createImage(
+                self.extent.width,
+                self.extent.height,
+                colour_format,
+                .optimal,
+                .{ .color_attachment_bit = true, .input_attachment_bit = true },
+                .{ .device_local_bit = true },
+                &self.colour_buffer_image_memory[i],
+            );
+
+            self.colour_buffer_image_view[i] = try self.createImageView(
+                self.colour_buffer_image[i],
+                colour_format,
+                .{ .color_bit = true },
+            );
+        }
+    }
+
     fn createDepthBufferImage(self: *Self) !void {
+        self.depth_buffer_image = try self.allocator.alloc(vk.Image, self.swapchain_images.len);
+        self.depth_buffer_image_memory = try self.allocator.alloc(vk.DeviceMemory, self.swapchain_images.len);
+        self.depth_buffer_image_view = try self.allocator.alloc(vk.ImageView, self.swapchain_images.len);
+
         // Get supported depth buffer format
         const formats = [_]vk.Format{ .d32_sfloat_s8_uint, .d32_sfloat, .d24_unorm_s8_uint };
         self.depth_format = chooseSupportedFormat(
@@ -673,19 +833,21 @@ pub const VulkanRenderer = struct {
             .{ .depth_stencil_attachment_bit = true },
         ) orelse return error.UnsupportedDepthBufferFormat;
 
+        for (0..self.depth_buffer_image.len) |i| {
             // Create depth buffer image
-        self.depth_buffer_image = try self.createImage(
+            self.depth_buffer_image[i] = try self.createImage(
                 self.extent.width,
                 self.extent.height,
                 self.depth_format,
                 .optimal,
                 .{ .depth_stencil_attachment_bit = true },
                 .{ .device_local_bit = true },
-            &self.depth_buffer_image_memory,
+                &self.depth_buffer_image_memory[i],
             );
 
             // Create depth buffer image view
-        self.depth_buffer_image_view = try self.createImageView(self.depth_buffer_image, self.depth_format, .{ .depth_bit = true });
+            self.depth_buffer_image_view[i] = try self.createImageView(self.depth_buffer_image[i], self.depth_format, .{ .depth_bit = true });
+        }
     }
 
     fn createGraphicsPipeline(self: *Self) !void {
@@ -903,6 +1065,48 @@ pub const VulkanRenderer = struct {
             null,
             @ptrCast(&self.graphics_pipeline),
         );
+
+        // -- Create second pass pipeline
+        // Second pass shaders
+        const second_vert_shader_module = try self.device.createShaderModule(&.{
+            .code_size = shaders.second_vert.len,
+            .p_code = @ptrCast(&shaders.shader_vert),
+        }, null);
+        defer self.device.destroyShaderModule(second_vert_shader_module, null);
+
+        const second_frag_shader_module = try self.device.createShaderModule(&.{
+            .code_size = shaders.second_frag.len,
+            .p_code = @ptrCast(&shaders.shader_frag),
+        }, null);
+        defer self.device.destroyShaderModule(second_frag_shader_module, null);
+
+        // Set new shaders
+        vertex_shader_create_info.module = second_vert_shader_module;
+        fragment_shader_create_info.module = second_frag_shader_module;
+
+        const second_shader_stages = []vk.PipelineShaderStageCreateInfo{ vertex_shader_create_info, fragment_shader_create_info };
+
+        // No vertex data for second pass
+        vertex_input_create_info.vertex_binding_description_count = 0;
+        vertex_input_create_info.p_vertex_binding_descriptions = null;
+        vertex_input_create_info.vertex_attribute_description_count = 0;
+        vertex_input_create_info.p_vertex_attribute_descriptions = null;
+
+        // Don't want to write to depth buffer
+        depth_stencil_create_info.depth_write_enable = vk.FALSE;
+
+        // Create new pipeline layout
+        const second_pipeline_layout_create_info: vk.PipelineLayoutCreateInfo = .{
+            .set_layout_count = 1,
+            .p_set_layouts = @ptrCast(self.input_set_layout),
+        };
+
+        self.second_pipeline_layout = try self.device.createPipelineLayout(&second_pipeline_layout_create_info, null);
+
+        pipeline_create_info.stage_count = @intCast(second_shader_stages.len);
+        pipeline_create_info.p_stages = &second_shader_stages;
+        pipeline_create_info.layout = self.second_pipeline_layout;
+        pipeline_create_info.subpass = 1;
     }
 
     fn createFramebuffers(self: *Self) !void {
@@ -911,7 +1115,11 @@ pub const VulkanRenderer = struct {
         // Create a frammebuffer for each swapchain image
         for (self.swapchain_images, 0..) |swapchain_image, i| {
             // Order matters
-            const attachments = [_]vk.ImageView{ swapchain_image.image_view, self.depth_buffer_image_view };
+            const attachments = [_]vk.ImageView{
+                swapchain_image.image_view,
+                self.colour_buffer_image_view[i],
+                self.depth_buffer_image_view[i],
+            };
 
             const framebuffer_create_info: vk.FramebufferCreateInfo = .{
                 .render_pass = self.render_pass, // Render pass layout the frambuffer will be used with
@@ -1056,6 +1264,30 @@ pub const VulkanRenderer = struct {
         };
 
         self.sampler_descriptor_pool = try self.device.createDescriptorPool(&sampler_pool_create_info, null);
+
+        // -- Create input attachment descriptor pool
+        // Colour attachment pool size
+        const colour_input_pool_size: vk.DescriptorPoolSize = .{
+            .type = .input_attachment,
+            .descriptor_count = @intCast(self.colour_buffer_image_view.len),
+        };
+
+        // Depth attachment pool size
+        const depth_input_pool_size: vk.DescriptorPoolSize = .{
+            .type = .input_attachment,
+            .descriptor_count = @intCast(self.depth_buffer_image_view.len),
+        };
+
+        const input_pool_sizes = [_]vk.DescriptorPoolSize{ colour_input_pool_size, depth_input_pool_size };
+
+        // Create input attachment pool
+        const input_pool_create_info: vk.DescriptorPoolCreateInfo = .{
+            .max_sets = self.swapchain_images.len,
+            .pool_size_count = @intCast(input_pool_sizes.len),
+            .p_pool_sizes = &input_pool_sizes,
+        };
+
+        self.input_descriptor_pool = try self.device.createDescriptorPool(&input_pool_create_info, null);
     }
 
     fn createDescriptorSets(self: *Self) !void {
@@ -1108,6 +1340,68 @@ pub const VulkanRenderer = struct {
         }
     }
 
+    fn createInputDescriptorSets(self: *Self) !void {
+        // Fill array of layouts ready for set creation
+        var set_layouts = try self.allocator.alloc(vk.DescriptorSetLayout, self.swapchain_images.len);
+        defer self.allocator.free(set_layouts);
+        for (0..set_layouts.len) |i| {
+            set_layouts[i] = self.input_set_layout;
+        }
+
+        // Input attachment descriptor set allocation info
+        const set_alloc_info: vk.DescriptorSetAllocateInfo = .{
+            .descriptor_pool = self.input_descriptor_pool,
+            .descriptor_set_count = @intCast(self.swapchain_images.len),
+            .p_set_layouts = &set_layouts,
+        };
+
+        // Allocate descriptor sets
+        try self.device.allocateDescriptorSets(&set_alloc_info, self.input_descriptor_sets.items.ptr);
+
+        // Update each descriptor set with input attachment
+        for (0..self.swapchain_images.len) |i| {
+            // Colour attachment descriptor
+            const colour_attachment_descriptor: vk.DescriptorImageInfo = .{
+                .image_layout = .read_only_optimal,
+                .image_view = self.colour_buffer_image_view[i],
+                .sampler = .null_handle,
+            };
+
+            // Colour attachment descriptor write
+            const colour_write: vk.WriteDescriptorSet = .{
+                .dst_set = self.input_descriptor_sets.items[i],
+                .dst_binding = 0,
+                .dst_array_element = 0,
+                .descriptor_type = .input_attachment,
+                .descriptor_count = 1,
+                .p_image_info = @ptrCast(&colour_attachment_descriptor),
+            };
+
+            // Depth attachment descriptor
+            const depth_attachment_descriptor: vk.DescriptorImageInfo = .{
+                .image_layout = .read_only_optimal,
+                .image_view = self.depth_buffer_image_view[i],
+                .sampler = .null_handle,
+            };
+
+            // Depth attachment descriptor write
+            const depth_write: vk.WriteDescriptorSet = .{
+                .dst_set = self.input_descriptor_sets.items[i],
+                .dst_binding = 1,
+                .dst_array_element = 0,
+                .descriptor_type = .input_attachment,
+                .descriptor_count = 1,
+                .p_image_info = @ptrCast(&depth_attachment_descriptor),
+            };
+
+            // List of input descriptor set writes
+            const set_writes = [_]vk.WriteDescriptorSet{ colour_write, depth_write };
+
+            // Update descriptor sets
+            self.device.updateDescriptorSets(@intCast(set_writes.len), &set_writes, 0, null);
+        }
+    }
+
     fn updateUniformBuffers(self: *Self, image_index: u32) !void {
         // Copy VP data
         const data = try self.device.mapMemory(