Скачать или смотреть Understanding Descriptor Sets in Vulkan: Can You Bind Descriptor Set 2 without Binding Sets 0 and 1?

Discover how to manage Vulkan's descriptor sets effectively, addressing common questions about binding without initializing prior sets.
---
This video is based on the question https://stackoverflow.com/q/71532527/ asked by the user 'Zebrafish' ( https://stackoverflow.com/u/4696802/ ) and on the answer https://stackoverflow.com/a/71532895/ provided by the user 'Nicol Bolas' ( https://stackoverflow.com/u/734069/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Can I bind a descriptor at 2 without binding 0 and 1?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding Descriptor Sets in Vulkan: Can You Bind Descriptor Set 2 without Binding Sets 0 and 1?

Introduction

When working with Vulkan, a low-level graphics API, you may encounter confusion regarding the binding of descriptor sets. One common question developers face is: Can you bind a descriptor set at index 2 without binding sets 0 and 1 first? This question stems from the way Vulkan requires pipeline layouts to be defined and how descriptor sets operate within those layouts.

In this guide, we will break down the problem and provide clarity on how to navigate descriptor set binding in Vulkan.

The Problem

Let's set the stage with a sample scenario. You have a pipeline with the following uniform declared:

[[See Video to Reveal this Text or Code Snippet]]

You then try to bind this descriptor set using the following command:

[[See Video to Reveal this Text or Code Snippet]]

Upon executing this, you receive a validation error stating that an invalid VkDescriptorSetLayout object was encountered. This validation error suggests that something is wrong with how you set up your pipeline layout.

Understanding the Source of the Error

The root cause of this issue lies in the way the Vulkan API processes pipeline layouts and descriptor sets. Here's a detailed breakdown:

Pipeline Layout Requirement: When you create a pipeline layout, you specify the number of descriptor sets through setLayoutCount.

[[See Video to Reveal this Text or Code Snippet]]

Zero-Based Indexing: Vulkan uses zero-based indexing for descriptor sets. This means that even if you do not explicitly use set 0 in your shaders, it still needs to be accounted for in the pipeline layout configuration.

Descriptor Set Count: When calling vkCmdBindDescriptorSets, the API checks if you correctly submitted all necessary layouts. In your case, since you only declared one set (set 1), Vulkan expects that you have also considered set 0, which is not the case here.

Pipeline Validation: The validation error originates from the vkCreatePipelineLayout call, not from the binding command. This means you need to provide a layout for every index up to the declared count.

Solution: Include Dummy Layouts

So, how can you resolve this situation? The following steps outline a clear solution:

Always Define All Sets: Even if you plan to use only certain descriptor sets in your shaders, you should always define layouts for all sets declared in your pipeline layout. This avoids validation errors and potential runtime issues.

Dummy Layouts: For the sets that you're not using (like sets 0 and 1 in your case), you can define dummy descriptor set layouts. While they do not have to be functional (i.e., you don’t need to bind resources to them), they must be valid layouts.

Example

Here's how you would set up a correct pipeline layout:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

In summary, Vulkan requires you to account for all descriptor sets declared in your shaders, even if you are not actively using them. By defining dummy layouts for any sets that you do not intend to use, you can avoid validation errors and ensure that your Vulkan application runs smoothly.

Always remember, managing descriptor sets is a fundamental part of using Vulkan effectively. By understanding the pipeline layout and descriptor bindings, you can unlock the full potential of Vulkan for your graphics applications.