adding Descriptors fundamental implementation

src/vulkan/DescriptorSetLayout.zig

@@ -8,7 +8,7 @@ const Self = @This();
 pub const ObjectType: vk.ObjectType = .descriptor_set_layout;
 
 owner: *Device,
-bindings: []const vk.DescriptorSetLayoutBinding,
+bindings: ?[]const vk.DescriptorSetLayoutBinding,
 
 vtable: *const VTable,
 
@@ -17,9 +17,15 @@ pub const VTable = struct {
 };
 
 pub fn init(device: *Device, allocator: std.mem.Allocator, info: *const vk.DescriptorSetLayoutCreateInfo) VkError!Self {
+    const bindings = if (info.p_bindings) |bindings|
+        allocator.dupe(vk.DescriptorSetLayoutBinding, bindings[0..info.binding_count]) catch return VkError.OutOfHostMemory
+    else
+        null;
+
     return .{
         .owner = device,
-        .bindings = allocator.dupe(info.bindings[0..info.binding_count]) catch return VkError.OutOfHostMemory,
+        .bindings = bindings,
+        .vtable = undefined,
     };
 }